A
- abaxial
- The side away from the axis, for instance the lower surface of a leaf.
- abort
- To abandon development of a structure of organ.
- abscission
- (adjective abscissile): A plant's normal shedding of an organ that is mature or aged, e.g. a ripe fruit or an old leaf.
- acaulescent
- An adjective descriptive of a plant that has no apparent stem, or at least none visible above ground. Examples include some species of Agave, Oxalis and Attalea.
- accrescent
- Increasing in size with age, such as a calyx that continues to grow after the corolla has fallen, for example in Physalis peruviana.
- -aceae
- The suffix added to the stem of a generic name to form the name of a family.
- achene
- A dry 1-seeded indehiscent fruit; e.g. members of the Ranunculaceae.
- acicular
- Slender or needle-shaped. See Leaf shape.
- acropetal
- Moving from roots to leaves, e.g. of molecular signals in plants.
- acrophyll
- The regular leaves of a mature plant, produced above the base; usually in contrast to bathyphyll.
- acrostichoid
- (describing a type of sorus) covering the entire abaxial surface of the frond, usually densely so, as in Elaphoglossum and Acrostichum.
- actinomorphic
- regular; radially symmetrical; may be bisected into similar halves in at least two planes. Generally applies to flowers in which the perianth segments within each whorl are alike in size and shape; compare irregular, regular, zygomorphic.
- aculeate
- Armed with prickles; e.g. the stem of a rose.
- acuminate
- Tapering gradually to a point.
- acute
- Sharply pointed; converging edges making an angle of less than 90°; compare obtuse.
- adaxial
- The side next to the axis; e.g. the upper surface of a leaf.
- adnate
- Fused to an organ of a different kind; e.g. a stamen fused to a petal; cf. connate.
- adventitious
- A structure produced in an abnormal position; e.g. an adventitious bud produced from a stem rather than from the axil of a leaf.
- adventive
- Introduced accidentally (usually referring to weeds).
- aerial
- Of the air; growing or borne above the surface of the ground.
- aestivation
- The arrangement of sepals and petals or their lobes in an unexpanded flower bud; cf. vernation arrangement of leaves in a bud.
- affinis
- With affinity to others, akin to; often used for a provisionally recognized but unnamed taxon considered close to that name, perhaps a hybrid or extreme variant.
- aggregate fruit
- A cluster of fruits formed from the free carpels of one flower, e.g. blackberry; cf. multiple fruit.
- agricultural weed
- see weed.
- -ales
- Suffix to the stem of a generic name or descriptive name to indicate that it applies to a taxon of the rank of order.
- alien
- Differing in nature, foreign; a plant introduced from elsewhere (exotic, introduced, non-native, non-indigenous).
- alkaloid
- Molecule with a nitrogenous base, many used as drugs; e.g. morphine, quinine, strychnine.
- alternate
- (as adjective) leaves or flowers borne singly at different levels along a stem includes spiralled parts; or (as verb) when something occurs between something else, for example stamens alternating with petals; compare opposite.
- amphitropous
- When the ovule is bent so that both ends are near each other; cf. anatropous, campylotropous, orthotropous.
- amplexicaul
- With the base dilated and clasping the stem, usually of leaves.
- anastomosing
- When veins are joined by cross-veins to form a network.
- anatropous
- When an ovule is inverted so that the micropyle faces the placenta (this is the most common ovule orientation in flowering plants); cf. amphitropous, campylotropous, orthotropous.
- androdioecious
- Of plants, having bisexual flowers and male flowers on separate individuals; cf. andromonoecious, polygamodioecious, polygamomonoecious, polygamous.
- androecium
- Male parts of flower; the stamens of a flower collectively; cf. gynoecium.
- androgynophore
- A stalk bearing both the androecium and gynoecium of a flower above the level of insertion of the perianth.
- androgynous
- With male and female flowers in the same inflorescence.
- andromonoecious
- Of plants, having bisexual and male flowers on the same individual; cf. andromonoecious, polygamodioecious, polygamomonoecious, polygamous.
- Anemophily
- Pollination by wind.
- angiosperms
- 'flowering plants'; plants with developing seeds enclosed in an ovary.
- annual
- A plant that completes its life cycle and dies within one year.
- anterior
- Away from the axis; usually abaxial.
- anther
- Pollen-bearing part of the stamen.
- anthesis
- Time of flowering; the stage at which the pollen is released from the anthers inside the bud onto the pollen presenter, usually corresponding with flower opening.
- antrorse
- Directed towards or upwards, e.g. of hairs on a stem; cf. retrorse.
- apetalous
- Without petals.
- apex
- (plural apices) The tip; the point furthest from the point of attachment.
- apiculate
- (Usually referring to a leaf) terminating in a short sharp flexible point; less abrupt than mucronate.
- apocarpous
- Of a gynoecium consisting with one or more carpels which are free from one another (or almost so); e.g. Ranunculaceae, Dilleniaceae.
- apomixis
- Reproduction, where viable seed or spores are produced without fertilization. A plant produced in this way is an apomict.
- appendage
- A secondary part attached to the main structure; an external growth that seldom has any obvious function.
- appressed
- Pressed closely, but not fused; e.g. leaves against a stem.
- aquatic
- Plants whose natural habitat is water: living in or on water for all or a substantial part of the organism's life span, generally restricted to fresh or inland waters.
- arachnoid
- Cobwebby, from being covered with fine white hairs.
- arborescent
- Tree-like in growth or general appearance.
- arboretum
- (plural arboreta) A taxonomically arranged collection of trees.
- archaeophyte
- An non-native plant that has been present in a geographic area for some time; cf. neophyte.
- areole
- (from areola) A space between the threads of a net; e.g. that part of a leaf surface defined by each of the elements of a vein network; as with cacti, the area between the veinlets of a leaf or the region of a cactus bearing the flowers and/or spines.
- aril
- (adjective arillate): A membranous or fleshy appendage (formed by expansion of the funicle) which partly or wholly covers a seed; e.g. the fleshy outer layer of lychee fruit and as found in Sapindaceae.
- aristate
- With a stiff, bristle-like awn or tip.
- article
- A segment of a jointed stem or of a fruit with constrictions between the seeds; an organ part that separates easily from the rest of the organ at a joint or articulation.
- articulate
- Jointed; separating freely, leaving a clean scar; for example the fronds of certain ferns where they join the rhizome.
- ascending
- Spreading horizontally, then becoming erect.
- asexual
- Of reproduction that does not involve the gametes; i.e. vegetative reproduction.
- attenuate
- Narrowing gradually.
- auricle
- (adjective auriculate): Ear-shaped lobe.
- awn
- Fine bristle-like appendage; e.g. terminating or on the back of glumes and/or lemmas of some grass spikelets.
- axil
- The upper angle between one part of a plant and another; e.g. the stem and a leaf.
- axile
- On an axis; of a placenta, on the central axis of the ovary.
- axillary
- Borne in or arising from the axil of a leaf.
- axis
- A line passing through the centre of something; it usually refers to the main stem of a whole plant or inflorescence.
Read more about this topic: Glossary Of Botanical Terms