| 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. | |
| acaulescent | lacking a stem cf. caulescent. | |
| accrescent | increasing in size from base to apex | |
| acicular | stiff and needle-like. | |
| aciculate | finely scored on the surface, as if scratched by a pin. | |
| acrocarpous | with the gametophyte producing the sporophyte at the end of the stem or main branch. Most acrocarpous mosses grow erect in tufts, and they are not or only sparsely branched. cf. pleurocarpous | |
| 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. | |
| acroscopic | facing or pointing towards the apex. cf. basiscopic. | |
| actinomorphic | radially symmetrical. cf. zygomorphic. | |
| aculeate | prickly. | |
| acumen | a long, tapering point. adj. acuminate. | |
| acuminate | tapering gradually to a protracted point. | |
| acute | terminating in a distinct but not protracted point, the converging edges separated by an angle of 45-90 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 cf. connate, coherent | |
| adventitious | arising in abnormal positions, e.g. rhizoids on a leaf. | |
| adventive | introduced to an area recently. cf. introduced, naturalised. | |
| aerenchyma | tissue incorporating large, gas-filled spaces formed by invagination of external surface. | |
| alar cells | specialised cells at the basal angles of a leaf, often distinctive in their size, shape, colour or ornamentation. | |
| alate | winged. | |
| 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. | |
| 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 |
|
| alveolate | pitted or honeycombed on the surface. Illustrative Image |
|
| amphigastria | (sing. amphigastrium) leaves that grow in a row on the lower side of a stem and which are usually smaller and have a different shape to other leaves. | |
| amplexicaul | of a leaf base, stem-clasping. Illustrative Image |
|
| analogous | structures or organs with similar functions that do not have a common phylogenetic origin; e.g. stomata and air pores cf. homologous. | |
| anastomosing | forming a network or reticulum. | |
| anastomosis | fusion to form a network. | |
| androecium | (pl. androecia) the male "gametoecium" consisting of antheridia, paraphyses and surrounding bracts. See also perigonium | |
| androgynous | see monoicous. | |
| 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. | |
| anisomorphic | describing related structures that exhibit more than one distinct type of size or shape | |
| anisophyllous | having dissimilar stem and branch leaves, e.g. in Sphagnum and Thuidium; or bearing two distinct types of leaves on the same stem, e.g. Hypopterygium and Racopilum. cf. isophyllous. | |
| annual | a plant that completes its life history within one year cf. biennial, perennial. | |
| annular | arranged in or forming a ring; leaves or branches arranged in a circle, e.g. Philonotis. | |
| annulus | one or more rings of enlarged, specialised cells between the mouth of the capsule and operculum, aiding dehiscence. | |
| anterior | On the side of the organ farthest from the axis. cf. posterior. | |
| antheridium | (pl. antheridia) the male gametangium; a multicellular stalked structure with a jacket of sterile cells, produces a large numbers of antherozoids (male gametes); globose to broadly cylindrical in shape. | |
| antherozoid | a motile male gametel in mosses propelled by two flagellae. | |
| anticlinal | oriented perpendicular (rather than parallel) to the surface. cf. periclinal. | |
| antrorse | bent, and pointing towards the apex. cf. retrorse. | |
| apical | at the apex or tip | |
| apical cell | a single cell at the apex of a shoot, leaf or other organ that divides repeatedly to produce new leaves, stems or other organs. | |
| apiculus | a short, abrupt point. adj. apiculate. | |
| apogamous | in which a sporophyte develops from gametophyte cells other than a fertilised egg. | |
| apogamy | the state of being apogamous. | |
| apomixis | vegetative reproduction or spore formation without fertilisation. | |
| apomorphic | of a character, derived. cf. autoapomorphic, pleisiomorphic, synapomorphic. | |
| apophysis | (pl. apophyses) a differentiated sterile neck at the base of the capsule, between the seta and urn; sometimes swollen or expanded (=hypophysis) | |
| apoplastic movement | the movement of water into a cell via the protoplast, being controlled by osmosis | |
| appendage | a structure arising from the surface or extending beyond the tip of another structure. In liverworts, flap that is attached to the ventral scale protecting the apical cell | |
| appendiculate | having short, thin transverse projections, e.g. on the endostomial cilia of the peristome (see trabeculae). | |
| appressed | closely applied, as flor leaves lying closely or flat against the stem. | |
| 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. | |
| archegonium | (pl. archegonia.) the female gametangium; a multicellular, flask-shaped structure consisting of a stalk, a swollen base (venter) containing the egg and a neck through which the antherozoid swims to fertilise the egg. cf. antheridium. | |
| arcuate | curved like a bow. | |
| areola | (pl. areolae) a space between the threads of a net. | |
| areolate | with small angular areas forming a network; the cellular pattern of the moss leaf is often termed areolation | |
| arista | the hard awn or bristle at the tip of a leaf, usually formed by an excurrent costa. adj. aristate. Illustrative Image |
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| aristate | having a stiff, bristle-like awn or tip. | |
| aristulate | having a small awn. | |
| arthrodontous | of a peristome, of triangular or linear teeth/segments consisting of differentially thickened wall-pairs. The teeth/segments are formed of part cells, in contrast to a nematodontous peristome in which they are formed of whole cells. | |
| articulate | jointed; having joints where separation may occur naturally; of a stem or peristome, having nodes or lines. | |
| ascending | sloping or curved upwards | |
| 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. Illustrative Image |
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| auricle | a small bulge or ear-like lobe at the basal margin of a leaf, e.g. in Papillaria and Calyptothecium; 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). | |
| autoicous | with male and female gametoecia on separate stems or separate branches of the same plant (monoicous). cf. synoicous, paroicous, dioicous | |
| autotrophic | independent of other organisms in respect of organic nutrition; able to fix carbon dioxide, by photosynthesis, to form carbohydrates. cf. epiphyte, parasite, saprophyte. | |
| awn | an arista or hairpoint, usually hyaline and formed of a projecting costa. Illustrative Image |
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| axil | the angle between the stem and any organ originating from it, e.g. a leaf or branch. adj. axillary. Illustrative Image |
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| axillary hair | a hair originating in a leaf axil, usually inconspicuous and often concealed by the leaf base. | |
| axis | the main stem; the conceptual line around which leaves, branches and other organs develop. |