| Name | Details | |
|---|---|---|
| abaxial | of the side or surface of an organ, facing away from the axis, e.g. the lower or dorsal surface of the lamina. cf. adaxial. | |
| abscission | the normal shedding from a plant of an organ that is mature or aged, e.g. a ripe fruit, an old leaf. adj. abscissile. | |
| acarodomatia | domatia adapted to provide shelter to beneficial mites. | |
| acaulescent | lacking an aerial stem or trunk. cf. caulescent. | |
| accessory fruit | a fruit, or group of fruits derived from one flower, in which the conspicuous, fleshy portion develops from the receptacle and is shed with the true fruit(s) attached. | |
| accrescent | continuing to increase in size after maturity, as the calyx of some plants after flowering. | |
| accumbent | of the orientation of an embryo, with the radicle lying against the edges of the two cotyledons. | |
| achene | a dry, indehiscent fruit formed from a superior ovary of one carpel and containing one seed which is free from the pericarp (often applied, less correctly, to the one-seeded fruits of Asteraceae). cf. cypsela. | |
| acicle | a slender, stiff, needle-like prickle. adj. acicular. Illustrative Image |
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| acicular | stiff and needle-like. | |
| aciculate | finely scored on the surface, as if scratched by a pin. | |
| acrodromous | of leaves, with two or more primary or strongly developed secondary veins running in convergent arches towards the apex. Arches not recurved at base. cf. brochidodromous, eucamptodromous, semicraspedodromous. | |
| acropetal | arising or developing in a longitudinal sequence beginning at the base and proceeding towards the apex. cf. basipetal. | |
| acrophyll | an adult lamina on the high-climbing portions of some ferns in Lomariopsis and related genera. cf. bathyphyll. | |
| acroscopic | facing or pointing towards the apex. cf. basiscopic. | |
| acrostichoid | of sporangia, densely covering the abaxial surface of the fertile frond, as in Acrostichum, i.e. not in distinct groups; of ferns, having the sporangia arranged as above. | |
| acrotonic | of flowering seasonal growth units (seasonal shoots), producing leaves below the inflorescence, cf. basitonic. | |
| actinomorphic | of a flower or calyx or corolla, radially symmetrical; symmetrical about more than one plane passing through the axis of the flower. cf. peloric, zygomorphic. | |
| aculeate | prickly. | |
| acumen | a long, tapering point. | |
| acuminate | tapering gradually to a protracted point. | |
| acute | terminating in a distinct but not protracted point, the converging edges separated by an angle less than 90 degrees. | |
| adaxial | of the side or surface of an organ, facing towards the axis, e.g. the upper or ventral surface of the lamina. cf. abaxial. | |
| adnate | fused to an organ of a different kind, e.g. applied to a stamen fused to a petal. cf. connate. Illustrative Image |
|
| adventitious | arising in abnormal positions, e.g. roots arising from the shoot system, buds arising elsewhere than in axils of leaves. | |
| adventive | introduced to an area recently. cf. introduced, naturalised. | |
| aerenchyma | tissue incorporating large, gas-filled spaces interspersed with the cells in a characteristic pattern. | |
| aerophore | a localised outgrowth associated with ventilation, as in Cyathea. | |
| aestivation | the arrangement of sepals and petals or their lobes in an unexpanded flower bud. cf. vernation . Illustrative Image |
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| aggregate fruit | a cluster of fruits formed from the free carpels of one flower. cf. syncarp . Illustrative Image |
|
| alate | winged. | |
| albumen | see endosperm. | |
| alete | used of a spore which forms alone, i.e. not in diads or tetrads, and hence lacks the laesura characteristic of monolete and trilete spores. | |
| allantoid | sausage-shaped. | |
| allopatric | of distributions of two taxa or populations, having different ranges of distribution. cf. parapatric, sympatric. | |
| alternate | of leaves or other lateral organs, borne singly at different heights on the axis; of floral parts, on a different radius, e.g. describing the position of stamens with respect to petals. cf. opposite . Illustrative Image |
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| alternitepalous | of floral parts, inserted alternately with the tepals. | |
| alveolate | pitted or honeycombed on the surface. Illustrative Image |
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| amphistomatic | bearing stomata on both upper and lower lamina surfaces. cf. hypostomatic. | |
| amplexicaul | of a leaf base, stem-clasping. Illustrative Image |
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| anadromous | a type of venation in which the first set of veins in each segment of the frond originates from the acroscopic side of the midrib, as in Polystichum australiense. cf. catadromous. | |
| analogous | structures or organs with similar functions that do not have a common phylogenetic origin; e.g. stomata and air pores cf. homologous. | |
| anastomosing | of veins, forming a network or reticulum. | |
| anastomosis | fusion to form a network, e.g. of veins in a leaf blade. | |
| anatropous | of an ovule, inverted so that the micropyle faces the placenta. | |
| anauxotelic | applied to inflorescences, parts of inflorescences or to axes that do not end in a flower, and in which growth does not continue beyond the flowering region, cf. auxotelic. | |
| androdioecious | having bisexual flowers and male flowers, on separate plants. | |
| androecium | the stamens of one flower collectively. | |
| androgynophore | a stalk bearing both the androecium and gynoecium of a flower above the level of insertion of the perianth. | |
| androgynous | having male and female flowers in the same inflorescence. | |
| andromonoecious | having bisexual and male flowers, on the same plant. | |
| androphore | a stalk bearing the androecium. | |
| anemophilous | pollinated by wind. | |
| aneuploidy | having a chromosome number that differs from the basic euploid number by the loss or addition of 1 or more chromosomes, e.g. in mosses the haploid number is n + 1 or n - 1, as opposed to polyploidy where the chromosome number is a multiple of the haploid number, e.g. 2n, 3n, 4n | |
| angiosperm | a seed-bearing plant whose ovules, and hence seeds, develop within an enclosed ovary. cf. gymnosperm. | |
| angustiseptate | with narrow partitions, cf. latiseptate. | |
| anisophyllous | having leaves unequal in size and shape at any one point along a branch. cf. isophyllous. | |
| anisotomous | dichotomies resulting in unequal branching. cf. isotomous. | |
| anisovalvate | when the two valves of a sporangium are unequal in size. cf. isovalvate. | |
| annual | a plant whose life span ends within one year after germination. cf. biennial, perennial. | |
| annular | arranged in or forming a ring. | |
| annular corona | raised fleshy tissue, usually in a ring, on the corolla around the base of the staminal column but not closely adnate to it. | |
| annulus | a ring; in ferns, the elastic ring of cells, forming part of the sporangium wall, that initiates dehiscence. | |
| anterior | of floral organs, on the side of the flower farthest from the axis. cf. posterior. | |
| anther | the pollen-bearing part of a stamen. cf. filament. Illustrative Images: anther dehiscence, anther attachments, direction of anther dehiscence, fusion of stamens |
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| antheridium | the fertile organ of a male gametophyte or the male organ of a bisexual gametophyte, in which male gametes are formed. pl. antheridia. cf. archegonium. | |
| anthesis | the time of opening of a flower. | |
| anthocarp | a false fruit consisting of the true fruit and the base of the perianth, as in Nyctaginaceae. | |
| antipetalous | inserted in front of the petals; opposite the petals. | |
| antisepalous | inserted in front of the sepals; opposite the sepals. | |
| antrorse | bent, and pointing towards the apex. cf. retrorse. | |
| apetalous | without petals. | |
| apical | of a placenta, at the top of the ovary. Illustrative images: anther attachment, ovule arrangement |
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| apiculum (= apiculus) | a short, abrupt, flexible point at the apex of a pinna or pinnule. adj. apiculate. | |
| apocarpous | of a gynoecium, consisting of two or more carpels which are free from one another or almost so. Illustrative Image |
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| apogamous | applied to pteridophytes in which a sporophyte develops from gametophyte cells other than a fertilised egg. | |
| apogamy | the state of being apogamous. | |
| apomict | a plant that produces viable seed or spores without fertilisation. | |
| apomorphic | of a character, derived. cf. autoapomorphic, pleisiomorphic, synapomorphic. | |
| appendage | a structure arising from the surface or extending beyond the tip of another structure. | |
| appressed | pressed closely against a surface (or another organ) but not united with it. | |
| aquatic | living in or on water for all or a substantial part of the life span (generally restricted to fresh/inland waters). | |
| arachnoid | composed of fine tangled hairs like a cobweb. | |
| arborescent | resembling a tree (applied to non-woody plants attaining tree height and to shrubs tending to become tree-like in size). cf. dendroid. | |
| archegonium | the fertile organ of a female gametophyte or the female organ of a bisexual gametophyte, in which female gametophytes are formed. pl. archegonia.cf. antheridium. | |
| arcuate | curved like a bow. | |
| areole | a space between the threads of a net; in Cactaceae, a cluster of hairs/spines/bristles borne at the node of a leafless stem; in Mimosaceae (for example), a distinct, oblong or elliptical area on the face of a seed, bounded by a fine line; on leaf laminas | |
| aril | a structure partly or wholly covering the testa of a seed and formed by expansion of the funicle. adj. arillate . Illustrative Image |
|
| aristate | having a stiff, bristle-like awn or tip. | |
| aristulate | having a small awn. | |
| article | a segment of a jointed stem, or of a fruit with constrictions between the seeds. | |
| articulate | jointed; having joints where separation may occur naturally; of a stem, having nodes. | |
| ascending | growing erect after an oblique or semi-horizontal beginning. | |
| asexual | not forming part of a cycle which involves fertilisation and meiosis. | |
| asperous | rough to the touch. | |
| asperulate | slightly rough to the touch. | |
| attenuate | tapering gradually; of pinnae, with sides narrowed concavely to the apex or to the base. Illustrative Image |
|
| auricle | an ear-shaped appendage at the base of a lamina, pinna, pinnule or corolla lobe. adj. auriculate. Illustrative Image |
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| autapomorphic | of a character, derived and unique to a given taxon or monophyletic group. cf. apomorphic, synapomorphic. | |
| autochthonous | of the inhabitants of a region, original; earliest known; (applied to an element of the Australian flora rich in endemics and believed to have been evolving in Australia for a long period of time). | |
| autotrophic | independent of other organisms in respect of organic nutrition; able to fix carbon dioxide, by photosynthesis, to form carbohydrates. cf. epiphyte, parasite, saprophyte. | |
| auxotelic | applied to inflorescences, parts of inflorescences or to axes that do not end in a flower, and in which growth continues beyond the flowering region, cf. anauxotelic. | |
| awn | a bristle-like appendage, e.g. on the tip or back of the lemma of a grass floret. Illustrative Image |
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| axil | the angle between a leaf or bract and the axis bearing it. adj. axillary. Illustrative Image |
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| axile | on an axis; of a placenta, on the central axis of the ovary. Illustrative Image |
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| axis | a stem, (commonly used for the main stem of a whole plant or of an inflorescence). |