Xerorchis
Xerorchis is a genus of the orchid family ( Orchidaceae). With two species colonized the tropical South America.
Description
The terrestrial plants growing 45 to 55 cm high. The rhizome is very short, ascending and wiry. The roots are long, thin, flexible and hairy, they have no radicum velamen. The shoot is slender, angular, stiff, simple or branched, first occupied with some low- leaves, which gradually merge indistinguishably in leaves. The leaves are arranged in two rows, the shoot axis is in the upper, leafy area zigzag. The leaves are linear, lanceolate or narrow - oval, pointed forward they end. Towards the top, the leaves are small, in terminal inflorescence, the bracts are deciduous leaves equal.
The inflorescence contains several to many flowers, these are rather small, light green, yellow-green or cream, they do not open wide. The ovary is slightly club-shaped, with a slender pedicel. The petals are not fused together. The sepals are lanceolate or ligulate, they end pointed, inside they are hairless, outside a little hairy. The lateral sepals are slightly askew. The petals resemble the sepals. The lip has a wedge- shaped base, in the middle there are several indistinct bars, front lip is entire or slightly three-lobed, often with a wavy margin. The column is slender, semi-circular in cross-section, hairy on the underside, with two appendages below the scar. The scar is bean-shaped. The stamen is bean-shaped to shaped hood, front blunt, top with a knob-like survey. It contains eight pollinia in two chambers, these are reversed ovoid to pear-shaped, laterally compressed, four contiguously. The pollinia attached to a rounded viscid disc ( Viscidium ). The separation layers between stamen and stigma ( rostellum ) is short and broad, it ends bidentate.
Dissemination
The two species of the genus Xerorchis are widespread in tropical South America. They come from sea level to 700 meters in front. They grow in the shade moist forests and roots in the humus layer.
Systematics and botanical history
The genus Xerorchis was set up by Rudolf Schlechter 1912. The name comes from the Greek words ξηρός xeros, "dry", and ὄρχις orchis, " testicles " (here: " Orchid" ), together. Worse was just the kind Xerorchis amazonica known, he writes for the explanation of the generic name: " The whole plant gives the impression of xerophytes ." The second type, Xerorchis trichorhiza was described in 1928 by Friedrich Wilhelm Ludwig Kraenzlin as Epidendrum and provided by Leslie A. Garay to the genus Xerorchis 1956.
Bad suspected a relationship of the genus Xerorchis with Elleanthus. Even in 1981 they ordered Robert Dressler also in this relationship, but later stated that a reliable assignment of Xerorchis was not possible. Dariusz Szlachetko presented in 1995 its own subtribe Xerorchidinae, which contained only the genus Xerorchis; He arranged them into a tribe Elleantheae, so again in the relationship of Elleanthus, a. Mark W. Chase, published in 2003 a classification of orchids, is in the Xerorchis in the tribe Nervilieae. Philip Cribb built in 2005 a separate tribes, Xerorchideae, with the only genus Xerorchis to emphasize the isolated position of the genus. A molecular genetic analysis showed that Xerorchis might actually be related to the Nervilieae, as the closest related genera were identified Diceratostele and Didymoplexis.