Dendrophylax Lindenii - Biology

Biology

This orchid is a leafless epiphyte of the Vandeae family. The plants consist of large masses of photosynthetic roots, anchored as a network on trees. It is found in moist, swampy forests in southwestern Florida and Cuba, and other Caribbean islands.

This orchid is an exceptional monocot, as it consists of a greatly reduced stem and the leaves have been reduced to scales. The bulk of the plant consists only of flat, cord-like, green roots with distinctive "track marks". These white track marks are called pneumatodes and function in much the same manner as stomata allowing the photosynthetic roots to perform gas exchange to support photosynthesis. These roots are used for moisture absorption and their chloroplasts for photosynthesis. The outer layer, the velamen, takes care of acquiring the nutrients and the water uptake. It also protects the inner layers.

This orchid is a distant relative of the African and Indian Ocean genus Angraecum; it seems that orchid seed, blowing like dust, crossed the Atlantic at least once and successfully colonized new habitat. This is an endangered orchid in the wild. Cultivation outside of its native environment has proven exceptionally difficult, but not impossible. Although many fail in the attempt to raise seedlings grown in sterile culture into adult plants, some have succeeded. This orchid is listed on the Appendix II of CITES and is fully protected by Florida state laws and should not be removed from the wild. Wild collected plants typically do not survive removal from their habitat, and die within a year. Plants in habitat are typically found growing on the central trunk or large main branches of living trees. D. lindenii seems to prefer Annona glabra (pond-apple) trees, or on occasion Fraxinus caroliniana (pop ash) trees, being from eye-level to only a few feet above eye-level.

This orchid blossoms between June and August, with one to ten fragrant flowers that open one at a time. The white flower is 3–4 cm wide and 7–9 cm long and is borne on spikes arising from the root network. During its peak fragrance emittance in the early morning, the scent is fruity, resembling an apple. The lower petal produces two long tendrils that twist slightly downward, resembling the back legs of a jumping frog. Its bracts are scarious - that is, thin, dry, membranous, and paperlike. Since the roots of this orchid blend so well with the tree, the flower often seems to be floating in midair, hence its name of "ghost orchid".

Pollination is done by the giant sphinx moth, the only local insect with a long enough proboscis to pollinate the flowers and access the extremely long nectar spur. In this regard it may be said to be the America's answer to the Madagascar orchid Angraecum sesquipedale, which led Charles Darwin to predict that a long-tongued species of moth would be found to fertilize it. Years later the moth responsible was discovered: Morgan's hawk moth Xanthopan morgani. The larvae of the giant sphinx moth feed on Annona glabra (pond apple), the same trees D. lindenii is typically associated with.