Glossary of Botanical terms

This file is a glossary of the terms used on the UK Flora website. Latin terms are included here.

Eventually, it is intended to illustrate the concepts referred to here, but as a first stage this glossary is presented without any illustrations.

Click on a letter below to take you to the first definition whose name begins with that letter.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

abaxial
facing away from the axis (usually the lower side of a leaf surface) (cf. adaxial).
abortion (adj. abortive)
the failure of a part to develop fully.
acaulescent
without a stem or stemless, although a stem-like peduncle is usually present.
accessory branches
branches (of an inflorescence) additional to the normal one in the bract axil.
accrescent
increasing in size with age (usually applied to a calyx which grows larger after anthesis).
achene
a small dry 1-seeded indehiscent fruit.
acicular
very narrow, stiff and pointed, usually round in cross-section.
acroscopic
on the side (usually of a pinna) towards the apex (opp. basiscopic).
actinomorphic
(of flowers) radially symmetric along more than 1 plane of symmetry (cf. zygomorphic).
aculeus (pl. aculei)
a conical elevation of a part of a plant, becoming hard and sharp-pointed.
aculeate
armed with prickles as opposed to spines.
acumen
a narrow point; sharp apex.
acuminate
gradually tapering to a sharp point with concave sides near the tip.
acute
with a tip that comes to a sharp point with ± straight-sided edges (cf. obtuse).
adaxial
facing towards the axis (usually the upper side of a leaf surface) (cf. abaxial).
adherent
when two or more dissimilar organs touch but are not fused (cf. coherent).
adnate
with unlike organs united (cf. connate).
adventitious
(of structures or organs) developing in an unusual position, e.g. of roots originating from a stem node.
aestivation
the manner in which the sepals and petals are arranged in bud.
alternate
arising singly at a node; this term includes spiral, as well as distichous arrangements.
alveolate
honeycombed; pitted with small cavities separated by narrow ridges.
alveolus (pl. alveoli)
a small cavity.
amplexicaul
having a widened base which clasps the stem.
anastomosing
  1. (of veins) joining up to form loops;
  2. (of bark) with ridges running together and then apart.
androecium
the male part of the flower.
androgynophore
an elongated part of the receptacle which bears both the male and female parts of the flower (see image of Passiflora subpeltata)
andromonoecious
having both bisexual and male flowers on the same plant but no purely female flowers.
androphore
an elongated part of the receptacle which bears the male parts of the flower only.
annual
completing its life cycle from seed to seed in less than 12 months.
annular
arranged in a circle or in a ring; the shape of a ring.
anterior
in a position most remote from the axis (opp. posterior).
anthela
  1. (in Cyperaceae) a cymose type of inflorescence with an umbel-like appearance due to tightly congested internodes, typically terminating a naked culm;
  2. (in Juncaceae) a panicle with the lateral axes exceeding the main axis.
anther
the part of the stamen which contains the pollen, usually divided into two pouches (thecae), joined together by a connective. Where there is only 1 theca, the anther is said to be 1-thecous.
anthesis
flowering time.
anticous
on the anterior side or away from the axis (opp. posticous).
antrorse
pointing forwards or upwards, or upwardly-directed (opp. retrorse).
apex (pl. apices)
the tip or end point of a structure.
apical
concerning or near the apex.
apical placentation
when the ovules are attached to the top of the ovary.
apiculum (adj. apiculate)
a short sharp point.
apomixis (adj. apomictic)
reproducing from seed which has been formed without sexual fusion of gametes.
appendage
a part added or attached to another, usually larger, structure.
appressed
pressed close against another organ. e.g. hairs, which lie flat against a leaf surface.
aquatic
living in water (cf. terrestrial).
arachnoid
covered with long, delicate, cobweb-like hairs.
arcuate
curved, like a bow.
areole
a surface area well-defined by bounding veinlets, lines or cracks; used to describe the raised area on the surface of the seeds in the Fabaceae subfamily Mimosoideae; also the area where spines and glochids arise on the stems of Cactaceae.
aril (adj. arillate)
an appendage, often fleshy or brightly coloured, covering or partly enclosing the seed.
arillode
a false aril.
arista (pl. aristae)
a long very narrow bristle-like point.
aristate
bearing an arista.
armed
possessing spines, thorns or prickles (opp. unarmed).
article
an individual part or segment of an articulated object.
articulated
jointed or separating at a certain point, and leaving a clean scar.
articulation
the point at which an organ is articulated.
ascending
curving upwards, oblique at first then erect.
attenuate
tapering gradually to a slender point.
auricle (adj. auriculate)
a small ear-like projection at base (occurring mainly in the Poaceae).
awn (adj. awned)
a fine bristle, usually terminating an organ.
axil
the angle between the axis and any organ which arises from it, e.g. the angle between a leaf and a branch.
axile placentation
when the ovules are attached to the central axis or the inner angle of the loculi within the ovary.
axillary
arising from the axil.
axis
(in general) the main or central line of development of any plant or organ.

B

baccate
berry-like.
barbate
bearded, having tufts of hairs.
barbed
with rigid points or lateral bristles pointing backwards.
barbellate
shortly or minutely barbed.
basal placentation
when the ovules are attached at the bottom of the loculus near the base of the ovary.
basifixed
of an anther, attached by its base to the filament (cf. dorsifixed).
basiscopic
on the side (usually of a pinna) towards the base (opp. acroscopic).
beaded
cylindrical with contractions and swellings at intervals (which may not be even); like a string of beads.
beak
a long prominent and substantial point, usually applied to the prolongation of ovaries and fruits.
beaked
possessing a beak.
berry
a fleshy fruit, usually several-seeded, the seeds immersed in pulp and not surrounded by a stony layer. Example: tomato.
bi-
a prefix meaning two or twice.
biconvex
convex on both sides.
biennial
completing its life cycle in 2 years (but not within one year), not flowering in the first.
biserrate
serrate, with the teeth themselves serrate.
bisexual
having both functional male and functional female parts (cf. unisexual).
brachyblast
short, axillary, densely crowded branchlet.
bract
a small often modified leaf found at the base of the pedicel or peduncle.
bracteal cup
(in Viscaceae) a cup-shaped structure formed by fused bracts.
bracteate
possessing bracts.
bracteolate
possessing bracteoles.
bracteole
a secondary bract; a small bract on the pedicel or close to the flower, between the bract and the flower
branchlet
the smallest part of a branch; the growth of the current or last growing season.
bulb (adj. bulbous)
a short underground stem with a crown of usually fleshy overlapping scale-like leaves. Example: an onion.
bulbil
a small bulb or tuber arising in the axil of a leaf or in an inflorescence, on the aerial part of the plant.
bullate
(of leaves) surface prominently raised between the veins.

C

caducous
falling unusually early.
caespitose
growing in tufts.
callus (pl. calli; adj. callose)
a thickened, raised mass of hardened tissue; hence
  1. (in Poaceae) a hard projection at the base of the floret or spikelet the sharp point of the seed;
  2. (in Orchidaceae) the raised structures, often consisting of ridges, papillae or projections, occurring on the upper surface of the lip.
calyculus (adj. calyculate)
outer bracts around the calyx, or an involucre resembling an outer calyx.
calyptra
a cap-like or lid-like covering of certain fruits or flowers that comes off in one piece. E.g. the perianth forms a calyptra which comes off when a Eucalyptus flower opens.
calyx (pl. calyces)
the outer envelope of the flower, consisting of sepals which may be free or united.
calyx lobes
the free part of the calyx.
calyx tube
the tube formed by the united sepals.
campanulate
bell-shaped, with a broad tube and a wide opening.
canaliculate
channelled or grooved.
canescent
covered with a grey pubescence or greyish colour.
capillary
hair-like, or very fine and slender.
capitate
  1. like the head of a pin (as in the stigma of some flowers or in some gland-bearing hairs);
  2. collected into compact head-like clusters (as the florets of the Asteraceae).
capitulum (pl. capitula)
a dense head-like inflorescence usually of sessile flowers.
capsule (adj. capsular)
a dry fruit produced by an ovary consisting of 2 or more united carpels and opening by slits or pores or breaking into pieces when ripe (cf. valve).
carpel
the basic unit of the female part of the flower, consisting of an ovary or part of an ovary with an associated style and stigma.
carpophore
a prolongation of the floral axis between the carpels which bears the fruit, as in the narrow stalk that supports the two mericarps in the fruit of the Apiaceae.
cartilaginous
hard and tough, as the skin of an apple pip.
caruncle
a fleshy, sometimes coloured, outgrowth near the hilum of a seed.
carunculate
possessing a caruncle (opp. ecarunculate).
caryopsis
a modified achene in which the seed and the ovary wall have become united; characteristic of the Poaceae.
cataphyll
  1. a much-reduced or scale-like leaf;
  2. (in e.g. Juncaceae or Poaceae) a leaf composed mostly of a leaf sheath or base with the lamina reduced to ± zero or a minute awn.
catkin
a spike-like inflorescence with many bracteate and loosely crowded unisexual flowers that is often pendulous and may resemble a cat's tail.
caudate
abruptly ending in a long tail-like tip or appendage.
caudex
a thickened, often woody, vertical or branched, perennial stem, usually subterranean or at ground level.
caudicle
(in Asclepiadaceae and Orchidaceae) the stalk of a pollinium.
caulescent
possessing a stem or stems.
cauline
borne on or arising from the stem.
cespitose
alternative spelling of caespitose.
chartaceous
of a papery texture; thin and opaque.
chasmogamous
(of flowers) opening normally (opp. cleistogamous).
ciliate
fringed with cilia.
ciliolate
minutely ciliate.
cilium (pl. cilia)
a hair on the margin of a structure.
cincinnus (pl. cincinni)
a tight, unilateral, scorpioid cyme.
circumscissile
see dehiscence.
cladode
a green leaf-like structure formed by a modified stem.
clathrate
(applied to scales of e.g. a rhizome) with a latticed appearance owing to the cells having thickened lateral walls and transparent surface walls.
clavate
club-shaped, i.e. thickened towards the end.
claw
the very narrow base of some petals (cf. limb).
cleistogamous
producing small flowers, often simplified and inconspicuous, which do not open and are self-fertilising (opp. chasmogamous).
climber
a plant which uses other plants or objects as a means of support but has its roots in the ground.
coccus (pl. cocci, adj. coccous)
a separate part of a lobed fruit, usually 1-seeded, as in some Rhamnaceae and Euphorbiaceae.
coherent
when two or more similar organs touch but are not fused (cf. adherent).
columella
a persistent, central axis around which the carpels of some fruits are arranged.
column
  1. (in Poaceae) the lower twisted portion of the awn;
  2. (in the Asclepiadaceae and Orchidaceae) the solid central structure formed by the union of style, stigma and stamens;
  3. (in Malvaceae) the tube of connate filaments.
columnar
shaped like a column.
coma
a tuft of hairs, especially on the tip of a seed; a tuft or crown of leaves.
comose
with a coma.
commissural
of a joint or seam, such as that between two adhering sepals.
commissure
each of the faces of two cohering carpels or mericarps (i.e. the plane along which the fruit separates; hence commisural face) in the Apiaceae.
compound
composed of several similar parts (opp. simple).
concolorous
with all parts of uniform colour, especially of the two surfaces of a leaf (cf. discolorous).
conduplicate
folded together lengthwise.
cone
a woody, ± conical structure of seed or pollen, borne beneath bract-like scales, arranged along an axis.
confluent
merging together, uniting.
connate
with like organs united (cf. adnate).
connective
see anther.
connivent
of two or more organs with their bases separated but their apices touching one another.
contorted
of sepals and petals in the bud when each overlaps an adjoining one on one side and is overlapped by the other adjoining one on the other side.
contracted
(as applied to the inflorescence of the Poaceae) not spreading, in which the branches of the inflorescence are erect and close to the main axis.
convolute
  1. rolled together, coiled;
  2. of sepals or petals in bud where one edge overlaps the next sepal or petal and the other edge is overlapped by the preceding sepal or petal.
cordate
(of surface) heart-shaped; broadly ovate with a rounded notch at the base.
coriaceous
with a thick and firm texture, similar to leather.
corm
a short thick underground stem, which grows vertically, for example in many Iridaceae.
corolla
the inner whorl of sterile appendages in the flower, made up of the free or united petals which are usually membranous and coloured (not green).
corolla lobes
the free part of the corolla.
corolla tube
the united part of the corolla.
corona
a whorl of appendages between the petals and the stamens, sometimes united to form a ring or cylinder, usually borne upon the petals or corolla tube (see image of Passiflora subpeltata).
corpusculum (pl. corpuscula)
connection between the arms of the pollinia in Asclepiadaceae.
corymb (adj. corymbose)
a raceme in which the pedicels become shorter towards the top so that all the flowers are approximately at the same level (i.e. a flat-topped inflorescence).
corymbose cyme
a flat-topped cyme, thus resembling a corymb in appearance.
costa (pl. costae)
the midrib of a pinna.
costule
the midrib of a pinnule or pinna segment.
costapalmate
a basically palmate leaf in which the petiole extends into the lamina as a well-defined axis, dividing the lamina in two.
cotyledon
the seed leaf, usually the first leaf or leaves which are produced and which usually differ from the following leaves.
crenate
(of margin) with crenations.
crenation
a blunt or rounded tooth, often wider than long.
crenulate
minutely crenate.
crispate
(of hairs) closely and stiffly curled.
crustaceous
hard, thin and brittle.
culm
a hollow or pithy, often jointed stem, typically unbranched or with nodes, found e.g. in Cyperaceae, Poaceae and Juncaceae.
cultivar
a cultivated variety.
cuneate
wedge-shaped, the narrow end below.
cupule
a cup-shaped organ.
cusp
an elongated, sharp, rigid point.
cuspidate
with the tip abruptly narrowed to a sharp, rigid point.
cyathium (pl. cyathia, adj. cyathial)
a small cup-like structure, characteristic of the genera Euphorbia, Monadenium and Synadenium, bearing on its rim variously-shaped glands (these sometimes separate and circular or crescent-shaped or fused into an entire marginal rim) with alternating lobes; within this cup are several naked male flowers, consisting of a stalked stamen and bracteole, and 1 central female flower bearing a 3-locular ovary with 3, often 2-fid, styles.
cyme (adj. cymose)
an inflorescence in which the central axis is terminated by a flower which opens first, and subsequent growth takes place from lateral branches which may themselves be terminated in a flower, so that further growth takes place from further lateral branches and so on. The oldest flowers are therefore at the apex (cf. raceme).
cystolith
a mineral concretion, usually crystals of calcium carbonate, within the epidermal cell of the leaves of some plants, (for example Urticaceae), almost always visible as light coloured spots in the leaves.

D

deciduous
  1. of leaves: falling off at the end of the growing season every year; (opp: evergreen);
  2. of other organs: falling before the majority of adjacent or associated organs.
declinate
(of stamens) curving downwards.
decumbent
(of stems) lying on the ground and tending to rise at the end.
decurrent
having the base prolonged down the axis. Usually applied to leaves where the lamina is continued downwards as a wing on the petiole or stem.
decussate
opposite leaves in 4 rows up and down the stem, in pairs alternating at right-angles.
dehiscence
the method or process of opening of a seed-pod or anther; loculicidal, when the split opens into a cavity or loculus, septicidal when the split occurs at a septum or partition and circumscissile when the object splits transversely, the upper part coming off as a lid.
dehiscent
(applied to an anther or seed-pod) splitting open, when ripe or mature, to shed its pollen or seed (opp: indehiscent). See also dehiscence.
deliquescent
melting away or breaking up into many small parts as in petals which soften and liquefy (Commelinaceae).
dendritic
(of hairs) much branched like the crown of a tree.
dentate
with a toothed margin, the teeth pointing outwards not forwards (cf. serrate).
-dentate
with a number of teeth.
denticulate
minutely dentate.
depressed
flattened from above.
diadelphous
forming two bundles or groups, as in the stamens of some legumes which have 9 united stamens and 1 free (cf. monadelphous).
dichasium (pl. dichasia, adj. dichasial)
a type of cyme in which the main axis and branches end in flowers that are subtended by two opposite branches (cf. monochasium).
dichotomous
(of branching) forking regularly into two.
dicotyledon
a plant having two cotyledons (cf. monocotyledon)
didynamous
in two pairs of unequal length; usually used in referring to 4 stamens, 2 short, 2 long.
diffuse
of branching that is open or loosely spreading.
digitate
(of leaflets) a compound leaf in which the leaflets arise from the same central point (cf. palmate). For this work, we have chosen digitate to mean leaves which are truly compound (i.e. composed of separate leaflets) and palmate leaves to be simple leaves where the radiating fingers are joined together near the base.
dilated
widened, flattened, expanded or enlarged.
dimidiate
(of pinnae or pinnules) in which the midrib forms the basiscopic margin for a significant distance.
dimorphic
having two forms.
dioecious
a plant with unisexual flowers, the male and female flowers borne on different plants (cf. monoecious).
disarticulating
breaking apart at the joints.
disciform
(of capitula of Asteraceae) with central florets bisexual with tubular corollas and marginal florets female or neutral but without ligules, their corollas tubular or 0.
discoid
  1. like a disc in shape;
  2. applied to a capitulum of the Asteraceae that lacks ray florets or ligulate florets and has only disk florets.
discolorous
of two colours, especially of a leaf where the two surfaces are of a different colour (cf. concolorous).
disk
  1. an enlargement of the receptacle usually surrounding or surmounting the ovary, usually in the form of a ring or cushion or composed of separate gland-like parts;
  2. (of Asteraceae) the usually discoid receptacle of the capitulum.
disk floret
(of Asteraceae) a tubular, 4- or 5-toothed or lobed floret on the disk of the capitulum.
distal
the part or end farthest away from the base or point of attachment (opp. proximal).
distichous
2-ranked, with (e.g.) leaves on opposite sides of a stem and in the same plane.
divaricate
spreading apart widely.
divergent
spreading apart but not as widely as divaricate.
domatium (pl. domatia)
a small tuft of hair; a cavity or pocket formed by a plant which is usually inhabited by insects, particularly ants or mites. Domatia are usually found in the axils of the lateral veins where they meet the main vein on the underside of the leaf and there is often a corresponding raised dome on the upper surface of the leaf.
dorsifixed
of an anther, attached by its back to the filament (cf. basifixed).
dorsiventral
with a distinct upper and lower side, two-sided, not terete.
dorsiventrally flattened
flattened in the plane of the back and front and not of the sides.
drupe (adj. drupaceous)
a ± fleshy fruit with one or more seeds each surrounded by a stony layer (e.g. a plum).
drupelet
a small drupe.

E

ebracteate
without bracts.
ecarunculate
without a caruncle (opp. carunculate).
echinate
covered with short spines or prickles.
eglandular
without glands.
ellipsoid
a solid object, elliptic in longitudinal section (adj. ellipsoidal).
elliptic
having the shape of an ellipse, broadest at the middle and narrower at the two equal ends.
elongate
lengthened, extended.
emarginate
with a notch at the apex.
embryo
the initial stage in the development of the plant while still enclosed within the seed.
emergent
growing in water, but with some parts of the plant raised above the surface.
endemic
confined to a region or country and not native anywhere else.
endocarp
the innermost layer of the ovary wall in a fruit, which may be hard or leathery as in a drupe or pyrene or fleshy as in Cucurbitaceae (see exocarp, mesocarp and pericarp).
endosperm
the nutritive material (mealy, oily, fleshy or horny) stored within the seed, and often surrounding the embryo.
entire
with an even and continuous margin without lobes, teeth or other indentations.
epi-
a prefix meaning on, upon or attached to.
epicalyx
an involucre of bracts below the flower resembling an extra calyx.
epidermis
the primary outermost layer of cells of all plant organs.
epigynous
(of flower) with perianth and stamens appearing to be borne upon the ovary; with inferior ovary (cf. hypogynous and perigynous).
epipetalous
borne upon the petals.
epiphyte (adj. epiphytic)
a plant which grows on another plant but without deriving any nourishment from it. Most often applied to orchids which grow on trees as opposed to being terrestrial.
equitant
folded lengthwise so that the base of each leaf enfolds the next.
erect
growing vertically.
erecto-patent
between erect and patent.
ericoid
resembling plants of the family Ericaceae, namely with small and sharply pointed leaves.
erose
(of margin) irregularly toothed, as if gnawed.
evergreen
retaining green leaves throughout the dormant season.
excentric
to one side; off centre.
excurrent
going out beyond the margin of an organ (as in the vein of a leaf going beyond the margin).
exocarp
the outer layer of the fruit, the outer part of the pericarp, the soft fleshy part of a drupe (cf. endocarp, mesocarp and pericarp).
exserted
projecting beyond, protruding. (opp. included).
extra-axillary
beyond or outside the axil.
extra-floral nectary
see nectary.
extrastaminal
outside the stamen whorl.

F

falcate
curved like a scythe or sickle.
family
a unit of classification above the level of genus and tribe but below that of order.
farinose
covered with a meal-like powder.
fascicle
a tight bundle or cluster.
fasciculate
arranged in fascicles.
fastigiate
strictly erect and parallel to other organs, e.g. with reference to stems or branches.
ferrugineous
rust-coloured or reddish-brown.
fertile
producing viable seeds or pollen (opp. sterile).
fibrous
composed of, or like, fibres.
-fid
cleft into a number of parts, but not as deeply as -sect (cf. -sect).
filament
the stalk of the anther.
filiform
thread-like.
fimbria (pl. fimbriae)
see fimbriate.
fimbriate
with the margin divided into a fringe of slender lobes (fimbriae).
flabellate
fan-shaped or broadly wedge-shaped.
flange
a winged or ribbed projection.
flexuous
having a more or less zigzag or wavy form.
floccose
clothed with woolly hairs, which are disposed in tufts or tend to rub off and adhere in small masses.
floret
  1. (in Poaceae) the lemma and palea with enclosed fl;
  2. (in e.g. Asteraceae) one of many small flowers in the involucre.
flower
the sexual reproductive structure of the angiosperms, usually consisting of calyx, corolla, androecium and gynoecium, borne on an axis.
foliaceous
having the appearance or nature of a leaf.
foliage leaves
ordinary leaves, as opposed to those which have undergone metamorphoses as bracts, petals etc.
-foliolate
(of leaf) with leaflet(s).
follicle
a dry, dehiscent fruit formed of one carpel, dehiscing along one side.
foveolate
marked with small pits or depressions on the surface.
free
not joined or united.
free basal placentation
when the ovules are attached to a central column arising from the base of the loculus within the ovary but not reaching the top.
free central placentation
when the ovules are attached to a central column in the centre of the single loculus; the column extends from the base of the loculus to the apex.
fruit
the ripe seeds and structure surrounding them.
fulvous
tawny, brownish-yellow or orange.
functionally unisexual
flowers in which both male and female parts are present but one is incompletely developed (i.e. functionally male flowers have poorly developed female parts).
funicle
the stalk of the ovule which attaches it to the placenta.
funnel-shaped
shaped like a funnel or cone, gradually widening.
furcate
forked.
fuscous
greyish-brown or dark greyish-brown.
fusiform
(of solid object) spindle-shaped, i.e. thick in the middle and tapering towards each end.

G

gamete
the sex cell or nucleus which combines with another gamete to form the fertilised egg.
gametophyte
a plant which produces gametes (cf. sporophyte).
gamopetalous
when the petals are united either entirely or at the base, into a tube, cup or ring (opp. polypetalous).
gamosepalous
when the sepals are united either entirely or at the base, into a tube, cup or ring (opp. polysepalous).
genera
see genus.
geniculate
bent abruptly like a knee.
genus (pl. genera)
a unit of classification above the rank of species but below the rank of family; a collection of genetically related species.
geophyte
a plant with perennating buds located on the plant below the soil.
gibbous
bulging or swollen on one side.
glabrescent
becoming glabrous with increasing age or maturity.
glabrous
without hairs.
gland
a protuberance or depression which secretes a fluid which is often sticky; if stalked, known as a glandular hair.
glandular
furnished with glands.
glaucous
pale bluish-green or with a pale bloom.
glochid (adj. glochidiate)
a very small spine or bristle, barbed at the tip.
glomerule
a compact cluster.
glomerulate
in the form of a glomerule.
glume
  1. (in Poaceae) an empty scale at the base of the spikelet; usually there are two, the lower glume and the upper glume;
  2. (in Cyperaceae) a single scale subtending each flower
glutinous
with a sticky exudate.
granulate
finely covered with very small granules.
gymnostegium
a structure formed by the union of the stamens with part of the pistil, as in the Asclepiadaceae.
gynobasic
arising from a deep depression in the centre of the ovary, between the ovary-lobes, or from the lower part of a simple ovary.
gynoecium
the female part of the flower.
gynophore
a development of the axis between the ovary and the other floral organs, whereby the ovary appears to be stalked.

H

hastate
when the base of a leaf has two ± triangular lobes which diverge away from the midvein (cf. sagittate).
haustorium (pl. haustoria)
the modified root with which a parasite enters the tissues of its host.
hemiparasite (adj. hemiparasitic)
a plant which can parasitise another plant but is also capable of growing by itself.
herb (adj. herbaceous)
any vascular plant which is not woody.
heterogamous
bearing separate male and female flowers or florets in an inflorescence or capitulum.
heteromorphic
of different forms.
heterosporous
producing spores of 2 sizes.
heterostylous
when the styles and stamens vary in relation to each other by length or position within the flowers of the same plant or plants of the same species (opp. isostylous).
hilum
a scar left on the seed at the point of attachment.
hirsute
covered with long, moderately stiff and not interwoven hairs.
hirtellous
minutely hirsute.
hispid
rough with stiff hairs.
hispidulous
minutely hispid.
homogamous
bearing one kind of flower rather than separate male and female flowers or florets in an inflorescence or capitulum.
hyaline
delicate, translucent or transparent tissue.
hypanthium
a cup-like or tubular structure formed above the base of the ovary with the stamens and perianth parts inserted on the rim.
hypocarp
a fleshy enlargement of the receptacle or of the stem, below the true fruit. E.g. the Cashew nut.
hypogynium
(in Cyperaceae) the basal part of the nutlet by which it is attached to the cupule within the glumes. In some species, not differentiated from the nutlet, in others it is distinct.
hypogynous
flowers in which the sepals and petals are attached beside or beneath the base of the ovary; with superior ovary (cf. epigynous and perigynous).
hysteranthous
with leaves appearing after the flowers.

I

imbricate
  1. overlapping like tiles;
  2. in a flower bud when one sepal or petal is wholly internal and one wholly external and the others overlapping at the edge only.
immersed
completely submerged or surrounded.
imparipinnate
a pinnate leaf with an odd number of leaflets, which has a single leaflet at the end of the leaf rhachis (cf. paripinnate).
incised
cut; slashed irregularly, ± deeply and sharply; an intermediate condition between toothed and lobed.
included
not projecting beyond; not protruding. (opp. exserted).
incurved
curved inwards.
indefinite
numerous and often variable in number.
indehiscent
not splitting open when ripe or mature (opp. dehiscent).
indumentum
any covering, such as hairs, wool, scales etc.
indurated
hardened and toughened.
indusium (adj. indusial)
a piece of tissue ± covering or enclosing a sporangium or group of sporangia.
inferior ovary
an ovary that is below the point of attachment of the sepals, petals and stamens (opp. superior ovary; cf. semi-inferior ovary).
inflexed
bent inward, turned abruptly inward.
inflorescence
the flowering portion of a plant.
inserted
attached to, borne upon or growing from.
internode
the portion of a stem between successive nodes.
interpetiolar
used to describe stipules situated between the petioles of opposite leaves (e.g. in the Rubiaceae).
interrupted
not continuous.
intrapetiolar
used to describe stipules situated between the petiole and the stem.
intrastaminal
within the stamens.
introduced (species)
introduced to a region deliberately or accidentally by man. (opp. native).
involucel
a whorl of bracteoles.
involucre (adj. involucral)
bracts forming a ± calyx-like structure around or just below the base of a usually condensed inflorescence (e.g. Asteraceae).
involute
inrolled; with the edges of the leaves rolled inwards by both margins so as to expose the abaxial surface (cf. revolute).
isostylous
(of flowers) when the styles and stamens do not vary in relation to each other by length or position (opp. heterostylous).

J

jugate
coupled or yoked together; applied to the leaflets of a pinnate leaf. E.g. 2-jugate: with 2 pairs of leaflets (i.e. 4 leaflets in all), sometimes also with a terminal leaflet in addition.

K

keel
  1. (in general) a projecting ridge, resembling the keel of a boat, running the length of an organ on the outer or under surface;
  2. the loosely united, lower petals of the Papilionoideae;
  3. the lower petal in the Polygalaceae.
keeled
with a longitudinal ridge running along the under surface of a flat or convex structure.

L

labellum
  1. (in Orchidaceae) the central petal, which is often lobed or spurred, and hence differs from the other two petals;
  2. (in Zingiberaceae) a large petaloid, sometimes lobed, object which together with the stamen forms the androecium.
lacerate
torn; irregularly cleft or cut.
lacinia (pl. laciniae)
a slender lobe.
laciniate
deeply and irregularly divided into slender lobes.
lacunar
with empty air space or gap within a tissue.
lamella (pl. lamellae)
a thin plate or layer.
lamelliform
having the form of a lamella.
lamina
the flattened and expanded part of a leaf or petal.
lanate
covered with soft, flexuous, intertwined hairs.
lanceolate
a plane shape which is narrowly egg-shaped in outline with the broadest part near the base.
lateral
on the side or along the margin (cf. terminal).
latex
a sap with milk-like appearance.
lax
loose, not dense.
leaf
an organ originating from and attached to a stem, usually with a short stalk attached to a flat lamina.
leaflet
a leaf-like part of a compound leaf.
lemma
(in Poaceae) the lower of the 2 bracts (the other is the palea) enclosing the flower
lenticel (adj. lenticellate)
small corky areas on the bark often with a colour different from the surrounding bark.
lepidote
clothed with scales.
liane
a woody climber.
ligulate
with the shape of a tongue or strap; possessing a ligule.
ligule
  1. (in Poaceae) a thin membranous or rim-like structure found at the top of the leaf sheath;
  2. the strap-shaped corolla found in the florets of certain Asteraceae;
  3. (in some Pteridophyta) a small flap of tissue on the adaxial side of the leaf.
limb
the upper, usually flattened and broad, part of a sepal or petal, above the claw (cf. claw).
linear
long and narrow, the sides parallel or nearly so.
2-lipped
when two or three lobes of a calyx or corolla stand separate from the others to form upper and lower lips.
lithophyte (adj. lithophytic)
a plant growing on rocks (cf. epiphyte).
lobe
any division of an organ not completely separated from the next.
-lobed
possessing lobes.
-locular
possessing loculi.
loculicidal
see dehiscence.
loculus (pl. loculi)
a chamber of an ovary or fruit which contains the ovules or seeds.
lodicules
(in Poaceae) minute scales, usually 2, outside the stamens and ovary; possibly vestiges of the perianth.
longitudinal
lengthways (cf. transverse).
lorate
strap-shaped.
lyrate
a pinnatifid leaf with a large terminal lobe and smaller lateral lobes.

M

medifixed
(of hairs) attached by the middle with the two branches pointing in opposite directions and often lying appressed to the surface.
membranous
of a thin texture and translucent.
mentum
(in Orchidaceae) a chin-like projection formed by the united bases of the lateral sepals and an extended column-foot.
mericarp
a single part of a schizocarp.
-merous
a suffix indicating the number of parts possessed by an organ.
mesocarp
the middle layer when 3 layers are present in the wall or pericarp of a fruit, often fleshy. (cf. endocarp, exocarp, pericarp).
midrib
the principal, usually central, vein of a leaf or other organ.
miombo woodland
woodland type dominated by trees of the species of Brachystegia, Julbernardia or Isoberlinia; an important vegetation type in south-central Africa.
monadelphous
with the filaments of the stamens in a single group or bundle (cf. diadelphous).
monocarpic
(of herbs) flowering and bearing fruit only once and then dying.
monochasium (pl. monochasia)
a one-sided cyme, i.e. where only 1 branch develops from under each successive terminal flower (cf. dichasium).
monocotyledon
a plant having a single cotyledon or seed-leaf. (cf. dicotyledon).
monoecious
a plant with unisexual flowers, the male and female flowers borne separately on the same plant (cf. dioecious).
monolete
with the dehiscence line unbranched, as in bilateral spores (cf. trilete).
monomorphic
having only 1 form.
monopodial
(of branching) where the main axis remains dominant so that all secondary shoots are clearly lateral (opp. sympodial).
mucilage (adj. mucilaginous)
a gluey, viscous liquid.
mucro
a short narrow point, projecting from the apex.
mucronate
provided with a mucro.
mucronulate
minutely mucronate.
muricate
rough, with sharp tubercles or protuberances.
muticous
blunt and without a point.
myco-heterotrophic
plants which obtain their nutrients through a mycorrhizal fungus that is attached to the root of a photosynthetic plant. Such species is neither a parasite (directly attached to the host) nor a true saprophyte (directly obtaining nutrients from dead matter).

N

-nate
e.g. 2-nate (binate) in pairs; 5-nate, in fives etc.
native
a plant which arose or became present in a region by natural means. (opp. introduced).
naturalised
an introduced plant which has become self-perpetuating in the flora area.
nectariferous
producing nectar.
nectary
a glandular structure which secretes a sugary liquid (nectar), either associated with a flower (floral nectary) or elsewhere on the plant (extra-floral nectary).
nerve
the principal or more conspicuous veins or ribs of a leaf, sepal or petal (cf. vein).
neuter
(of flower) with functional stamens and functional pistils both 0.
node
the place on a stem at which a leaf or other organs arise.
nodose
having nodes, knots or swellings.
nut
a 1-seeded, indehiscent fruit, with a hard dry outer covering.
nutlet
a small nut.

O

ob-
a prefix meaning "opposite", "inverse" or "against". When used as a prefix before a word describing the shape of an organ, it means that the organ is attached to its stalk at the opposite end to the usual case (cf. obcordate).
obcordate
a cordate leaf, but attached at the unlobed end, so that the apex is notched.
oblanceolate
the inverse of lanceolate.
oblate
transversely broadly elliptic.
oblique
  1. slanting;
  2. (of leaf) not symmetrical about the midrib at the base of the leaf.
oblong
a plane shape almost rectangular in outline but with rounded ends.
obovate
the inverse of ovate.
obovoid
the inverse of ovoid.
obsolete
not evident or apparent; rudimentary.
obtuse
a blunt or rounded end, the margins forming an angle greater than 50º (cf. acute).
ochrea (pl. ochreae)
a tubular stipule, forming a membranous sheath around the stem near the leaf base.
operculum (adj. operculate)
a lid or cover which comes off by a transverse line of dehiscence.
opposite
  1. of leaves or branches when two are borne at the same node on opposite sides of the stem;
  2. of other organs (e.g. stamens) when opposite or placed in front of the petals instead of alternating with them.
ostiole
an opening or pore.
ovary
that part of the female part of the flower which contains the ovules and eventually becomes the fruit
ovate
(of a plane shape) egg-shaped in outline with the broadest part near the base.
ovoid
(of a solid shape), ovate in outline, with a circular transverse section.
-ovulate
possessing ovules, e.g. 3-ovulate, with 3 ovules.
ovule
the immature seed in the ovary before fertilisation.

P

palate
the raised part of the lower lip of a corolla which closes or almost closes the throat.
palea
the bract, usually membranous, on the adaxial side of the floret in the Poaceae.
pallid
pale in colour.
palmate
(of a leaf) a leaf which is not truly compound in which the lobes are arranged like the fingers of a hand (cf. digitate).
palmatifid, palmatilobed, palmatipartite, palmatisect
the palmate equivalents of pinnatifid, pinnatilobed, pinnatipartite and pinnatisect (q.v.).
pandurate
fiddle-shaped.
panicle
  1. a compound raceme or cyme, the primary branches being themselves branched;
  2. (in the Cyperaceae) an inflorescence in which the culm has leaves spread along it and flowering branches arise from the axils of upper leaves or bracts.
paniculate
in the form of a panicle.
pantoporate
(of a pollen grain) with apertures scattered over the whole surface.
papilionaceous
(of flowers) resembling those of the Leguminosae subfamily Papilionoideae.
papilla (pl. papillae)
a minute nipple-like protuberance.
papillose
covered with papillae.
pappus
the ring of hairs or scales around the top of the fruit in the Asteraceae.
paraphyses
sterile hairs, sometimes clavate or with an enlarged apical cell, occurring among sporangia in a sorus.
parasite (adj. parasitic)
a plant which derives its food wholly or partially (hemiparasite) from other living plants to which it is directly attached.
parietal placentation
when the ovules are attached to the inner surface of the peripheral or outside wall of the ovary, or the outer wall of the loculus.
paripinnate
a pinnate leaf with an even number of leaflets and no single leaflet at the end (cf. imparipinnate).
-partite
deeply cleft into a number of divisions, e.g. 2-partite, with 2 divisions etc.
patelliform
shaped like a small dish, circular and with a rim.
patent
spreading ± at right-angles.
pectinate
divided at the edge to form many parallel parts like the teeth of a comb.
pedate
used for leaves which are palmately divided, with the lateral lobes again partially divided.
pedicel
the stalk of a single flower or of a spikelet.
pedicellate
possessing a pedicel, i.e. stalked.
peduncle
the stalk of an inflorescence or part of an inflorescence
pedunculate
possessing a peduncle.
pellucid
translucent.
peltate
an organ, the stalk of which is attached to a flat surface and not the margin; the attachment is not necessarily central.
pendulous
hanging down or drooping.
penicillate
with a coma shaped ± like a pencil or brush.
pepo
a fleshy fruit with hard outer rind and without septa or separate chambers within, as in the Cucurbitaceae.
perennial
living for 3 or more growing seasons.
perianth
the outer sterile whorls or envelopes of a flower, made up of identical perianth segments, or of two different kinds of perianth segments: sepals (calyx) or petals (corolla). See also tepal.
pericarp
the wall of the ripened ovary or fruit (between the loculi and the outer surface); it may be of one or as many as 3 layers called the exocarp, mesocarp and endocarp.
perigynous
(of flower) with perianth and stamens arising from a hypanthium that is not adnate to the ovary (cf. hypogynous and epigynous).
persistent
remaining attached, not falling off.
petal (adj. petaline)
an individual segment or member of the corolla.
petaloid
like a petal in colour and form; may be applied to bracts, sepals or stamens (cf. sepaloid).
petiolate
possessing a petiole.
petiole
the stalk of a leaf.
petiolulate
possessing a petiolule.
petiolule
the stalk of a leaflet.
phloem
the part of the vascular system made up of living cells that function primarily in the conduction of food; the inner bark.
phyllary
(of Asteraceae) an involucral bract.
phyllode
a green flattened petiole resembling a leaf.
pilose
with long soft hairs.
pinna (pl. pinnae)
the primary division of a pinnately compound leaf .
pinnate
a leaf composed of more than 3 leaflets arranged in two rows along a common stalk or rhachis.
2-pinnate
a leaf in which the primary divisions are themselves pinnate; similarly 3-pinnate etc.
pinnatifid
with the margin divided more than halfway to the midvein or centre and forming pinnately arranged lobes.
pinnatilobed
with the margin divided to about half the distance to the midvein or centre and forming pinnate lobes.
pinnatipartite
with the leaf divided almost to the midvein or centre and forming pinnate lobes.
pinnatisect
with the leaf divided to the midvein or centre and forming pinnate lobes.
pinnule
the primary segment of a pinna.
pistil
the individual female structure which contains the ovule and will produce the seeds.
pistillode
a reduced non-functioning pistil that does not produce seeds; often present in functionally male flowers.
placenta
the part of the ovary, sometimes but not always, thickened or raised, to which the ovules are attached.
plano-convex
convex on one side and flat on the other.
plicate
longitudinally folded or pleated.
plumose
feathered, as bristles which have fine hairs on each side, e.g. the pappus of some Asteraceae.
pod
(in the Fabaceae) a dry dehiscent fruit consisting of one carpel, usually opening along the two sutures into two halves.
pollen
dust-like grains contained within an anther.
pollinarium
(in Orchidaceae) the whole structure of the pollinia, stipes or caudicle and viscidium.
pollinium (pl. pollinia)
a mass of waxy pollen grains transported as a single unit, as in many Orchidaceae.
polygamous
when a plant or different plants of the same species have both bisexual and unisexual flowers.
polymorphic
occurring in many forms.
polypetalous
when the petals are free i.e. not united (opp. gamopetalous).
polysepalous
when the sepals are free i.e. not united (opp. gamosepalous).
pore
a small opening.
posterior
in position nearest to the axis (opp. anterior).
posticous
on the posterior side, next to the axis (opp. anticous).
prickle
a small sharp outgrowth from the bark or surface.
probract
(in Cucurbitaceae) a leaf-like bract at the base of the inflorescence
procumbent
with stems lying along the ground.
process
a projection or projecting part.
prolate
(of a pollen grain) having a polar axis of greater length than the equatorial diameter.
proliferous
bearing adventitious buds (q.v.) on the leaves or in the flowers, capable of rooting and forming separate plants.
prophyll
a much reduced leaf or bract.
prostrate
lying closely along the surface of the ground.
prothallus
a small, usually flat, plant body not clearly differentiated into stems and leaves, formed by the germination of a spore.
proximal
the part or end nearest to the base or point of attachment (opp. distal).
pruinose
covered with a whitish wax or very fine powder.
pseudaril
an aril-like structure found with the seeds of Commiphora.
pseudo-
a prefix meaning false.
pseudobulb
the bulb-like stem of certain orchids.
pseudopetiole
a petiole-like structure, typically separating a leaf sheath from a leaf lamina.
pseudostaminode
(in Amaranthaceae) a staminode-like structure.
puberulent
minutely pubescent.
pubescent
with soft short hairs.
pulvinus (adj. pulvinate)
a swelling, shaped like a cushion or pad, round or flattened, usually occurring at the base of the leaf or petiole.
punctate
dotted or shallowly pitted, often with glands.
pungent
ending in a sharp rigid point.
pyrene
the stone of a drupe, consisting of one or few seeds with a hard covering, enclosed in fleshy tissue.
pyriform
pear-shaped.
pyrophyte (adj. pyrophytic)
a plant able to tolerate fire or needing fire to stimulate flowering.

R

raceme
an inflorescence whose growing points continue to add to the inflorescence and in which there is usually no terminal flower The youngest flowers are therefore nearest the apex. The flowers are borne along a single axis and are stalked (cf. cyme and spike).
racemose
arranged in a raceme.
radiate
a capitulum of the Asteraceae with marginal, female or neuter, ligulate ray florets and central bisexual or male, tubular disk florets.
radical
(of leaves) arising from the base of a stem or from a rhizome.
radicle
the embryonic root; the part of the developing embryo that will produce the root.
raphe
the part of the stalk of the ovule (funicle) that is united or coherent to the outer wall of the ovule and forms a ridge on the surface of the seeds.
ray
  1. (in Apiaceae) one of the primary branches of a compound umbel;
  2. (in Asteraceae) the strap-shaped extension borne by in some cases by the marginal florets.
ray floret
a type of floret in the Asteraceae
receptacle
the end of the flower stalk to which the floral parts are attached.
receptacular scales
bracts or bristles subtending individual florets in the heads of the Asteraceae.
recurved
curved backwards.
reflexed
bent backwards or downwards.
reniform
kidney-shaped, i.e. with a notch at the base and rounded at the apex.
repand
when the margin is slightly uneven or wavy by turning inwards and outwards but to a lesser extent than sinuate. (cf. sinuate)
resupinate
twisted through 180º, as in the pedicel and ovary in most species of Orchidaceae; upside-down.
reticulation (adj. reticulate)
a network or net-like arrangement of veins or fibres.
retinaculum (pl. retinacula)
  1. (in Acanthaceae) the persistent hook-like funicle;
  2. (in Asclepiadaceae and Orchidaceae) the structure to which the pollinium is attached.
retrorse
pointing backwards or downwards; backwardly-directed (opp. antrorse).
revolute
with margins rolled outwards towards the abaxial side (cf. involute).
rhachilla
a small axis or rhachis; the central axis of the spikelet in Poaceae and Cyperaceae.
rhachis (pl. rhachides)
  1. the principal axis of an inflorescence above the peduncle;
  2. the axis on which the leaflets of a compound leaf are inserted.
rhipidium (pl. rhipidia)
a cymose inflorescence with branches alternating from one side of the vertical axis to the other, normally flattened in one plane and fan-shaped.
rhizome (adj. rhizomatous)
a horizontal stem, on or under the ground, lasting more than one growing season.
rhombic
diamond-shaped.
rosette
leaves crowded together on account of the very short internodes.
rostellum
  1. a small beak;
  2. (in Orchidaceae flowers) a projection from the upper edge of the stigma.
rosulate
in a rosette.
rotate
wheel shaped; a corolla with very short tube and lobes spreading out at right angles to the axis.
rotund
a leaf shape intermediate between broadly elliptic and circular.
ruderal
growing amongst rubbish or rubble; of waste or weedy places.
rudimentary
incompletely developed.
rufous
rusty or reddish-brown.
rugose
with wrinkles or grooves in the surface.
rugula
(applied to the upper lip of some Acanthaceae) a fine wrinkle or fold.
rugulose
minutely rugose.
runcinate
with teeth pointing backwards towards the base.

S

saccate
forming a small sac or bag.
sagittate
arrow-shaped; the base has two acute lobes which point backwards to the base of the petiole (cf. hastate).
salver-shaped
with a narrow tube opening suddenly into a wide cup-shaped mouth.
samara
a dry indehiscent fruit, part of the wall of which forms a flattened wing. Example: Pterolobium stellatum.
saprophyte
a plant which derives its food wholly or partially (partial saprophyte) from dead organic matter. According to this page, there are no saprophytic flowering plants; species normally referred to as saprophytic are myco-heterotrophic.
sarmentose
with long slender stolons or whip-like branches.
scaberulous
minutely rough.
scabrid
rough to the touch, usually because of the presence of very short harsh hairs.
scandent
climbing.
scape
a leafless peduncle arising from ground level (usually from a basal rosette of leaves) in acaulescent plants.
scapose
possessing a scape, or scape-like.
scarious
membranous, thin and dry, not green.
schizocarp
a dry fruit breaking up into 1-seeded nut-like parts (each part called a mericarp), as in many genera in the Malvaceae.
scorpioid
coiled like a scorpion’s tail (in one plane).
scrub
a community dominated by shrubs.
-sect
cleft into a number of parts, almost to the base or midrib (cf. -fid).
secund
all directed to one side.
seed
a reproductive unit formed from the fertilised ovule.
semi-
a prefix meaning partially.
semi-amplexicaul
partially amplexicaul.
semi-inferior ovary
an ovary which is in part united with and in part free from the calyx and corolla (cf. inferior ovary and superior ovary).
sensu
in the sense of.
sepal
an individual segment or member of the calyx.
sepaloid
sepal-like, i.e. green and herbaceous (cf. petaloid).
septate
divided by septa.
septicidal
see dehiscence.
septifragal
the form of dehiscence in which the septa are separated from the valves.
septum (pl. septa)
a partition or cross-wall.
-seriate
arranged in whorls, rows or series, e.g. 3-seriate, arranged in 3 series.
sericeous
with silky appressed hairs.
serrate
with a toothed margin, the teeth more or less regular and pointing forwards (cf. dentate).
serrulate
minutely serrate.
sessile
without a stalk.
seta (pl. setae)
a bristle or stiff hair.
setaceous
shaped like a bristle.
setose
covered with stout rigid bristles.
setulose
minutely setose.
sheath
a tube-like structure sometimes split longitudinally for part or whole of the length with the two margins overlapping, that encloses an organ either completely or partially, e.g. a leaf-sheath of Poaceae.
shrub
a woody plant, typically with several main stems, that at maturity does not attain tree height (5 m).
shrublet
a small shrub.
silicula (pl. siliculae)
a dehiscent, 2-valved, 2-celled capsule less than 3 times as long as wide (cf. siliqua).
siliqua (pl. siliquae)
a dehiscent, 2-valved, 2-celled capsule more than 3 times as long as wide (cf. silicula).
simple
  1. unbranched;
  2. (of a hair) unbranched, with or without a terminal gland;
  3. (of a leaf) not separated into leaflets, although the leaf lamina may be deeply lobed (opp. compound).
sinuate
when the margin is uneven or wavy by turning inwards and outwards but not deeply enough to be lobed (i.e. in and out, not up and down) (cf. repand and undulate).
sinus
the depression between 2 lobes or teeth.
smooth
used in the sense of “not rough” (sometimes elsewhere used to mean glabrous).
sordid
of a dull, dirty or muddy colour.
sorus (pl. sori; adj. soral)
a group of sporangia.
spadix
an inflorescence with the flowers borne on or sunken into a thick and often fleshy spike-like axis as in the Araceae.
spathaceous
resembling or bearing a spathe.
spathe
a large bract or pair of bracts subtending and often enclosing a flower or inflorescence
spathella
(in Podostemaceae) a capsule-like structure enclosing the flower buds.
spatheole
a small spathe enclosing part of an inflorescence; typically (in some Poaceae) surrounding a single raceme or a pair of racemes.
spathulate
spoon-shaped.
species (pl. species)
the basic unit in a taxonomic classification denoting a group of organisms that appear more similar to each other than to any other group and are usually assumed to be able to interbreed and produce fully fertile progeny.
spicate
arranged in a spike.
spiciform
spike-like in appearance and not necessarily with the true structure of a spike.
spike
a simple racemose inflorescence with sessile flowers or spikelets (cf. cyme and raceme).
spikelet
a small spike in which the individual flowers are subtended by and enclosed in bracts; found in the Poaceae and Cyperaceae.
spine
a hard sharp-pointed structure, often long and narrow.
sporangium (pl. sporangia)
a structure containing spores.
spore
a small asexual reproductive body, usually unicellular, and always without tissue differentiation.
sporocarp
an organ enclosing the sorus or sori in heterosporous ferns, hardened in Marsilea, membranous in Azolla and Salvinia.
sporophyll
a leaf bearing or subtending sporangia.
sporophyte
a plant which produces spores (cf. gametophyte).
spur (adj. spurred)
a slender usually hollow, sac-like extension of some part of the flower
squamella (pl. squamellae)
(in Ascolepis) the perianth scale in the spikelet.
squarrose
spreading or recurved at some point above the base.
stamen
one of the male reproductive organs of the plant.
staminal tube
filaments united so as to form a tube.
staminode (pl. staminodia)
a modified stamen that produces no pollen.
standard
  1. (in Leguminosae subfamily Papilionoideae) the large adaxial petal of pea-like corollas;
  2. (in Iridaceae) the narrow inner petals of Iris and other genera.
stellate
star-shaped; often applied to stellate hairs which have several branches radiating from a central point.
stem
the main axis of the plant or a branch of the main axis which (at first) produces leaves at the nodes.
sterile
not producing viable seeds or pollen (opp. fertile).
stigma (adj. stigmatic)
the receptive surface, usually at the top of the style, of the female part of the flower, to which the pollen grains adhere.
stilt root
a supporting root which arises from lower nodes above the ground, usually on weak or tall grasses which require extra support.
stipe
  1. the stalk supporting a carpel or gynoecium;
  2. (in ferns) the stalk of the frond.
stipel (pl. stipellae; adj. stipellate)
a structure similar to a stipule but occurring at the base of the leaflets of a compound leaf.
stipitate
supported on a stipe.
stipulate
possessing stipules.
stipule (adj. stipular)
a scale-like or leaf-like appendage usually at the base of the petiole.
stolon (adj. stoloniferous)
  1. a short-lived, horizontal stem, either above, on or below the surface of the ground, rooting at one or more nodes;
  2. (in the Cyperaceae) long and slender scale-covered subterranean rhizomes ending in buds which give rise to new plants.
striation (adj. striate)
fine, parallel, longitudinal lines, grooves or ridges.
strigose
with stiff appressed straight hairs.
strigulose
minutely strigose.
strobilus (pl. strobili, adj. strobilate)
a fir-cone, or an inflorescence or fruit that resembles one by having large and imbricated scales.
strophiole (adj. strophiolate)
an appendage to the hilum of the seed.
style
that part of the female part of the flower connecting the stigma to the ovary.
stylopodium
a disk-like enlargement at the base of the style.
sub-
a prefix meaning "slightly, "somewhat", "almost" or "below".
subglabrous
very slightly, but persistently, hairy (cf. glabrous; glabrescent).
submarginal
almost marginal; positioned very close to the margin.
subopposite
almost but not quite opposite.
subshrub (adj. subshrubby)
a plant with a woody base to the stems but with upper part of the stems herbaceous.
subspecies
a unit of classification below the rank of species and above the rank of variety, often used for grouping geographical variants of a species.
subtend
to extend under, or be opposite to, another structure.
subulate
flat and narrow, tapering from the base to a sharp tip.
succulent
fleshy and juicy, thick and soft within.
suffrutex (pl. suffrutices; adj. suffrutescent)
a shrublet, usually producing leafy and flowering shoots each year from a woody underground stock.
sulcate
grooved or furrowed.
superficial
on the surface.
superior ovary
an ovary that is borne above the attachment of the sepals, petals and stamens. (cf. inferior ovary and semi-inferior ovary).
supra-axillary
arising above an axil.
suture
the line along which two parts have been united or the line along which a structure splits open.
sympodial
(of branching) where the terminal bud ceases to grow (or its function and position are taken another structure such as a flower) and growth is continued by a lateral bud or branch (opp. monopodial)
synandrium
an androecium of a male flower with united anthers.
syncarp
a structure consisting of several united, usually fleshy, fruits.

T

taxon (pl. taxa)
a taxonomic entity of any rank.
tendril
an organ to assist a plant to climb, formed from the whole or part of a stem, leaf or petiole.
tepal
a general term for the parts of the perianth (i.e. the petals and sepals), often used when the petals and sepals cannot be readily distinguished.
terete
circular or oval in cross-section, without grooves or ridges.
terminal
borne at the end of a stem and limiting its growth (cf. lateral).
ternate
in threes (e.g. 'leaves ternate' means leaves in whorls of 3).
terrestrial
on or in the ground (cf. aquatic and epiphytic).
tessellate
having a chequered pattern.
testa
the outer coat of a seed.
tetrad
a group of 4 pollen grains or spores.
tetragonous
four-angled.
thallus (pl. thalli)
a vegetative body not differentiated into stems and leaves.
theca (pl. thecae)
see anther.
-thecous
see anther.
thorn
a sharp-pointed branch.
throat
  1. the orifice of a gamopetalous corolla or gamosepalous calyx;
  2. the area of the corolla between the limb and the tube;
  3. (of Poaceae) the open part of the junction between the leaf sheath and its lamina.
thyrse (adj. thyrsoid)
a panicle, usually compact, with an indeterminate main axis but with cymose sub-axes.
tomentellous
slightly tomentose.
tomentose
with a tomentum.
tomentum
a dense felty mass of matted or tangled hairs.
transverse
crosswise (cf. longitudinal).
tree
a woody plant, typically with one main trunk, that at maturity reaches at least 5 m.
triangular
having ± the shape of a triangle.
tribe
a unit of classification above the level of genus and below that of family.
tricolpate
(of a pollen grain) having 3 elongate longitudinal apertures.
trigonous
of a solid body, triangular in section but obtusely angled.
trilete
(e.g. of spores) having three scar lines forming a Y, or basically tetrahedral (cf. monolete).
trimorphic
having three forms.
triquetrous
of a solid body, triangular in section and acutely angled.
truncate
with the base or apex at right angles to the midvein as if cut across at the bottom or top.
tube
the fused part of a corolla or calyx.
tuber
a swollen portion of a stolon or rhizome.
tuberous
resembling a tuber or producing tubers.
tubercle
a swelling, knob or thickened protuberance on a surface, sometimes found at the base of a hair.
tuberculate
covered with tubercles.
tuft (adj. tufted)
a loose, compact or dense cluster of vegetative shoots and/or stems.
turbinate (top-shaped)
cone-shaped but with the broad portion up and the pointed portion down.
turion
a reduced branch, with highly modified photosynthetic leaves and stipules, borne in a leaves axil or at a stem apex.
twining
climbing by winding the stem around the support.

U

umbel (adj. umbellate)
an inflorescence in which the pedicels all arise from a common point.
unarmed
devoid of thorns, spines or prickles (opp. armed).
uncinate
with a hook at the end.
undulate
wavy in a plane at right angles to the surface (i.e. up and down not in and out) (cf. sinuate).
unguiculate
contracted at base into a claw.
unisexual
producing either male or female gametes but not both; having either functional stamens or functional ovaries but not both (cf. bisexual; cf. functionally unisexual).
urceolate
shaped like a water pot or urn, with a rounded base and short broad tube that is narrowed above and slightly expanded at the very top.
utricle
a flask-like or bottle-shaped object enclosing a female flower in the genus Carex.

V

valvate
when the edges of petals or sepals meet without overlapping.
valve
one of the parts produced by the splitting of a capsule when ripe. (cf. capsule)
variety
a unit of classification below the level of species; varieties are separated on the basis of form and colour but the varieties are usually not geographically separated and individuals of different varieties can freely interbreed.
vascular bundle
a strand or unit of phloem or xylem, with or without a surrounding sheath, which carries water and nutrients.
vascular plants
species of plants which belong to the two major divisions, Pteridophyta and Spermatophyta.
vein
a small strand of vascular tissue (cf. nerve).
velutinous
with a dense indumentum of fine, soft, straight hairs; velvety.
venation
the arrangement of the veins in a leaf.
verrucose
covered with rough wart-like projections.
versatile
(of anthers) turning freely on its support or stalk.
vesicle (adj. vesicular)
a sac, bladder or cavity, usually small and filled with gas or fluid.
vestigial
a trace or mark left by a structure no longer developed but present in ancestral forms.
villous
covered with long, soft, weak hairs.
virgate
long slender and straight; wand-like.
viscidium (pl. viscidia)
(in Orchidaceae) a viscid part of the rostellum, which is clearly defined and removed with the pollinia as a unit, and serves to attach the pollinia to an insect or other agent.
vitta (pl. vittae)
resinous canal on the fruit of some Apiaceae.
vlei
seasonally moist or wet, sloping, shallow, grass-covered depression.

W

whorl
more than 2 organs of the same kind arising at the same level.
wing
  1. (in general) any flat expansion of an organ;
  2. each of the two lateral petals in the flowers of the Papilionoideae;
  3. each of the two inner, usually petaloid, sepals in the flowers of the Polygalaceae.
winged
possessing a wing.

X

xerophytic
adapted to a dry climate or habitat.
xylem
the principal cells of the wood; important in water movement.

Z

zygomorphic
applied to flowers having bilateral symmetry, so that the corolla may be divided equally only along 1 plane of symmetry (cf. actinomorphic).

Copyright: Mark Hyde, 2008-18

Hyde, M.A. (2018). UK Flora: Glossary.
http://www.ukflora.info/glossary.php, retrieved 18 February 2018

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