Leaves of Orchids

Leaves of Orchids
The shape of the leaves, often an important characteristics in plant identification, is of little significance in orchid identification.

The manner in which the young leaves are packed when young is, however, a very important character in generic identification.

The young leaves may be rolled, so that one margin overlaps the other and the back of the young leaf is rounded (technically known as supervolute or, somewhat incorrectly as convolute, or they they may be folded once longitudinally technically known conduplicate).

The character is generally easy to see in plants with young leaves, and it is also generally easy to decide even when the leaves are mature, as rolling or folding persists at the base.

In some genera in which the plants bear few leaves it may be difficult to decide on this character when the leaves are mature; the following features should help in making a decision.

Folded leaves generally retain a longitudinal line or small fold down the middle over most of their length, and usually have a definite keel on the outside towards the base; very hard, leathery leaves are almost all folded.

Rolled leaves are sometimes pleated or have prominent veins, do not usually have a single line or fold down the middle, and are rounded on their backs towards the base.

In a few genera and species the leaves are terete or cylindric with a groove or grooves; such leaves cannot be said to be either rolled or folded when young, but they are keyed here with the genera with folded leaves.
Leaves of Orchids