Dichromanthus
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Dichromanthus cinnabarinus , illustration |
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| Garay |
Dichromanthus is a genus from the family of the orchid (Orchidaceae). It contains only four species that are distributed from Arizona and Texas through Mexico to Honduras.
description
The species of the genus Dichromanthus are terrestrial, small, perennial , herbaceous plants. The roots arise in clusters at the base of the shoot, they are fleshy, cylindrical to stalked, fusiform, thickened, not hairy. The leaves are close together in a rosette, less often they are distributed in the lower half of the shoot. The leaf shape is oval to lanceolate, the leaf base is wedge-shaped without a stalk into a sheath surrounding the stalk. The leaves are present at flowering time.
The terminal, upright inflorescence is a multi-flowered raceme . The flowers are arranged one-sided in some species. The peduncle is only covered with glandular hair in the upper area, and the bracts are also covered with glandular hairs. The bracts that cover the peduncle are tubular to lanceolate, they end pointed. The bracts are large and colored, only with Dichromanthus michuacanus they wither quickly. The resupinated flowers are white, yellow, orange or brick red, Dichromanthus michuacanus produces fragrance during the day. The ovary is spindle-shaped, hairy and somewhat twisted. It points upwards, the tubular flower envelope is horizontal or slightly nodding. The sepals are shaped roughly the same, the outer sides are hairy. The edges of the three outer petals lie against each other at the base and form a tube, the tips are turned back. The lateral sepals together with the extension of the column (column base) form a protruding nectarium at their base . The dorsal sepal is fused with the column at the base. The petals adhere to the outer petals. The lip is divided into three parts: at the base it is abruptly narrowed, creasingly folded, at the edge with two thickened nectar glands. The middle part is wider, the sides are turned up in a runny manner and adhere to the column. The front part is also wide, the tip is bent down. In the lower third, the lip is covered with velvety hair on the inside (sometimes also on the outside). The column is rather short, hairy on the underside, at the base it protrudes beyond the point of attachment at the ovary (column foot). The stamen is oval and pointed. The column surrounds it with a thick, but not far protruding edge (clinandrium). The pollinia are whitish, club-shaped with an elongated adhesive disc (Viscidium), they protrude clearly from the stamen. The scar is heart-shaped, bilobed with raised edges. The separating tissue between the stigma and the stamen (rostellum) is elongated triangular to linear in shape.
Hummingbirds are suspected to be pollinators in Dichromanthus cinnabarinus and Dichromanthus aurantiacus . Dichromanthus michoacanus could be pollinated by bumblebees ( Bombus ).
Occurrence
Dichromanthus is distributed from the south of the USA (Texas) via Mexico, Guatemala, El Salvador and Honduras. They occur at altitudes from 800 to 3300 meters. The locations are light oak and pine-oak forests, tropical dry forests, dry bushes and grasslands.
Systematics and botanical history
Dichromanthus is classified within the tribe Cranichideae in the subtribe Spiranthinae . The genus was described by Leslie Garay in 1982 with the type species Dichromanthus cinnabarinus .
The genera Deiregyne , Mesadenus and Schiedeella are closely related to Dichromanthus . Within the genus, Dichromanthus cinnabarinus is the sister species of the other two species.
The name Dichromanthus is made up of the Greek prefix δι- di , "two" and the words χρῶμα chroma , "color" and ἄνθος anthos , "blossom".
The species of the genus Dichromanthus :
- Dichromanthus aurantiacus (Lex.) Salazar & Soto Arenas : It occurs from Mexico to Honduras.
- Dichromanthus cinnabarinus (Lex.) Garay : It occurs from southwest Texas to Guatemala.
- Dichromanthus michuacanus (Lex.) Salazar & Soto Arenas : It occurs from southern Arizona to southwest Texas and from Mexico to Honduras.
- Dichromanthus yucundaa Salazar & García-Mend. : The species first described in 2009 occurs only in the Mexican state of Oaxaca .
supporting documents
Most of the information in this article comes from:
- Leslie A. Garay: A generic revision of the Spiranthinae . In: Botanical Museum Leaflets of Harvard University . tape 28 , no. 4 , 1982, pp. 313-314 .
- Alec M. Pridgeon, Phillip Cribb, Mark W. Chase, Finn Rasmussen (Eds.): Genera Orchidacearum. Orchidoideae (Part 2). Vanilloideae . tape 3/2 . Oxford University Press, New York and Oxford 2003, ISBN 0-19-850711-9 , pp. 197-199 .
Individual evidence
- ↑ Gerardo A. Salazar, Mark W. Chase, Miguel A. Soto Arenas, Martin Ingrouille: Phylogenetics of Cranichideae with emphasis on Spiranthinae (Orchidaceae, Orchidoideae): evidence from plastid and nuclear DNA sequences . In: American Journal of Botany . tape 90 , 2003, p. 777-795 ( amjbot.org ).
- ↑ a b c d e Rafaël Govaerts (Ed.): Dichromanthus. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved December 8, 2016.
