Pleurothallis longissima Lindl.

• Authority

  Britton, Nathaniel L. Flora Borinqueña.

• Family

  Orchidaceae

• Scientific Name

  Pleurothallis longissima Lindl.

• Description

  Species Description - This pretty orchid remained unreported from Porto Rico until detected growing on a cliff between Ponce and Adjuntas in 1931, by Mr. James Thorp, while engaged in the Soil Survey conducted by the Bureau of Chemistry and Soils of the United States Department of Agriculture. He has given the following description of the locality: "The yellow Pleurothallis was found on the northwestern side of a hard limestone cliff. It was growing in partly decayed vegetable matter, about two inches thick, on the bare limestone, shaded by overhanging rocks during the early part of the day and a few small trees and bushes also offer a partial shade for part of the colony. The plants were quite abundant in the small spot observed." Specimens have been kindly studied and determined for us by Mr. Gates Ames, of Harvard University, expert investigator of tropical American orchids, who has informed us that this species, long supposed to be restricted in distribution to Jamaica, and not otherwise known from the West Indies until found by Mr. Thorp, has wide distribution from Mexico to Panama. The flowers of the Porto Rico plant and the plants themselves are considerably smaller than those of typical specimens from Jamaica. Seven other species occur in Porto Rico, for the most part on forest trees in wet districts, at higher elevations. Pleurothallis (Greek, side-frond, the flower-clusters are borne along side the leaves) is a genus established by the English botanist Robert Brown in 1813; it consists of an enormous number of species of small orchids, estimated as perhaps as many as 500, all natives of tropical America, growing mostly on trees, but sometimes on rocks. They have tufted, or creeping, 1-leaved stems, and small flowers, in slender clusters, borne at the base of the leaf, and subtended by a sheath (spathe). The 3 sepals are nearly alike, the 2 lateral ones usually partly united; the petals are narrow, mostly shorter than the sepals; the lip is mostly 3-lobed; the anther is operculate, containing 2, waxy pollen-masses (pollinia). The fruit is a small capsule. Pleurothallis longissima is smooth, with numerous, round, tufted, rather slender stems from 6 to 12 centimeters long, with a joint below the middle; the stalkless leaves are firm in texture, oblong, or somewhat broader above the middle than below, blunt, from 6 to 12 centimeters long and from 1 to 2 centimeters wide. The slender, one-sided, elongated flower-cluster is from 7 to 40 centimeters long, subtended by a spathe from 1 to 2 centimeters long; the individual flowers have very short stalks; the sepals are from 4 to 9 millimeters long, the lateral ones united; the narrow, pointed petals are a little shorter than the sepals; the broad lip about one-half as long.

• Discussion

  Yellow Pleurothallis Orchid Family Pleurothallis longissima Lindley, Folio Orchidacea, Pleurothallis 31. 1859.