abscission detachment of a plant part, usually used with re reference to a leaf
accession a numbered plant in the collection
acuminate referring to an apex (leaf. sepal. etc.) which tapers to a fine point
acute referring to an apex that is broadly tapered
adnation (adj. adnate)  fusion of unlike parts, e.g. labellum with column; contrasted with connation
agar a gelatinous product made from agar agar derive from various marine algae
allele a form in which a gene may occur
anatomy structure and arrangement of cells and tissues
anther cap the outer deciduous cap or case which covers the pollinia
anther the pollen-bearing part of a stamen
anthesis the opening of the flower
apex the tip of a leaf, bract, stem or tepal
apical at the tip
apicule (adj. apiculate) a short, sharp point
artificial hybrid a hybrid produced as a result of the transfer by man of pollen from one plant to another
artificially propagated plants produced in cultivation, from cuttings or seeds of a stock maintained for the purpose
asymbiotic seedlings grown in sterile culture, not in a symbiotic relationship with a fungus
auricles ear like lobes, often paired, as on labellum pr column
autoclave the an apparatus within which very high     temperatures are produced by steam under pressure; used to sterilise laboratory equipment and media
axil (adj.axillary) the angle formed by a petiole and stem or, on inflorescence, pedicel and rachis