Learn About Orchids and Orchid Care

Learn About Orchids and Orchid Care

Tuesday, March 15, 2005

Leaf

They have simple leaves with lengthwise veins. Their types can be very different; ovate, lanceolate, or orbiculate. The leaves can be enormous or minute, or they can even be lacking (as in Polyrrhiza lindenii). Their size and shape can be an aid in identifying the orchid, since it reflects the taxonomic position.

The structure of the leaves corresponds to the specific habitat of the orchid. Species that typically bask in sunlight or grow on sites which can be occasionally very dry have thick, leathery leaves. The laminas are covered by a waxy cuticle. These retain their necessary water supply. Shade species, on the other hand, have tall, thin leaves. They cannot stand a drop in atmospheric humidity or exposure to direct sunlight. Between these two extremes, there is a whole range of intermediate forms.

The leaves of most orchids live on, attached to their pseudobulbs, for several years. Other species, especially those with plicate leaves, shed their aged leaves annually, through an articulation between the lamina and the petiole sheath, and develop new leaves together with new pseudobulbs (as in the genus Catasetum).

The leaves of some species can be most beautiful. The leaves of the Macodes sanderiana, a semiterrestrial or lithophyte, show a sparkling silver and gold veining on a light green background. The cordate leaves of Psychopsiella limminghei are light brownish green with maroon-puce markings, created by flower pigments. The attractive mottle of the leaves of Lady's Slippers from temperate zones (Paphiopedilum) is caused by uneven distribution of chlorophyll.

Some genera, such as Aphyllorchis and Taeniophyllum lack leaves. They depend on their roots, which contain chlorophyll, for photosynthesis.

0 Comments:

Post a Comment

<< Home