| Name | Structure/ Category | Description |
|---|---|---|
| Arachnoid | [Buds, Leaf lower surface, Leaf upper surface, Phyllaries, Sepals, Young twigs] {pubescence type} | With fairly sparse, fine, white, loosely tangled hairs; cobwebby. |
| Areole | a small pit or cavity (as that from which spines arise in cacti) | |
| Aril | an exterior covering or appendage of certain seeds that develops after fertilization as an outgrowth from the funiculus and envelopes the seed | |
| Aristate | [Leaf apices, Leaflet apices, Petal apices, Phyllary apices, Sepal apices] {shape} | Bearing a prolonged, slender, stiff, usually straight tip; awned or bristled. |
| Armature | Any kind of sharp defense such as thorns, spines, or prickles. | |
| Armed | (1) [Bark of mature trunks] {surface appearance} | Bearing any kind of sharp defense such as thorns, spines, or prickles. |
| Armed | (2) [Seed cone scales] {armature} | Bearing a hook, prickle or other sharply pointed structure on the end of the cone scale. |
| Ascending | [Leaves, Petals, Phyllaries, Sepals] {vertical orientation} | Spreading at the base and then curving upward to an angle of 45 or less relative to the bearing structure. |
| Astringent | Foliage with a soapy or medicinal aroma because of the presence of saponins and other chemicals. | |
| Asymmetric | (1) [Calyx, Corolla] {symmetry} | Not divisible into essentially equal halves along any plane. |
