Pelexia

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Pelexia
Pelexia adnata, illustration from "The Botanical Register"

Pelexia adnata , illustration from "The Botanical Register"

Systematics
Order : Asparagales (Asparagales)
Family : Orchids (orchidaceae)
Subfamily : Orchidoideae
Tribe : Cranichideae
Sub tribus : Spiranthinae
Genre : Pelexia
Scientific name
Pelexia
Poit. ex Rich.

Pelexia is a genus from the family of the orchid (Orchidaceae). It contains 90 species that are common in tropical America.

description

The Pelexia species are small, herbaceous plants that mostly grow terrestrially. There are also rarely epiphytic or semi-aquatic species. The roots stand together in clusters or along a rhizome , they are fleshy and cylindrical or stalked and thickened in a spindle-shaped manner. In some species the individual rungs are connected by a long rhizome, in others it is absent and the rungs are close together. The leaves are in a basal rosette. The leaves are stalked, the leaf blade is lanceolate to oval in shape, it ends pointed or elongated. The leaves are mostly green, but some species also have a light pattern, rarely they are brown in color.

The racemose inflorescence is multi-flowered, the flowers sit tightly or loosely together. The upright inflorescence axis is hairy, especially in the upper area. The bracts are spaced apart or completely surround the peduncle. The flowers of some species are fragrant; they are greenish, yellow or white in color, less often reddish brown. The ovary is cylindrical to somewhat spindle-shaped, sessile or very short stalked, somewhat twisted, mostly hairy. The sepals are spread apart and do not form a tube, on the outside they are usually somewhat hairy. The dorsal sepal is concave to hood-shaped, together with the petals it forms a helmet over the flower. The lateral sepals are fused to a sack or spur at the base. They lie against the dorsal sepal, at the base they run down a bit on the ovary and are thus asymmetrical. The lip is fleshy, abruptly narrowed (nailed) at the base and there arrow-shaped, rarely eyed. The sides of the lip are turned up and cling to the column . The column is rather thick, long, hairy, reaching at the base beyond the point of attachment on the ovary (with foot). The scar consists of two separate or one adjacent surface. The separating tissue between stigma and stamen (rostellum) is rather soft and flexible, linear to tongue-shaped, it ends bluntly or cut off. The stamen is oval to heart-shaped, it ends bluntly. It contains the club-shaped pollinia with a thick, oval to almost round viscidium. The capsule fruit is oval, it contains numerous narrow spindle-shaped seeds .

Pollination by bumblebees is known of two species: Dressler reports this for Pelexia ekmanii , Singer and Sazima made detailed observations of Pelexia oestrifera .

Occurrence

Pelexia is found in tropical and subtropical America. The distribution area stretches from Florida and Mexico in the north to Argentina, Paraguay and Uruguay in the south. They colonize altitudes up to 3100 meters. The individual species occur in different forms of vegetation, in damp or drier forests, in swamps or in various bushes and grasslands.

Systematics and botanical history

Pelexia is classified within the tribe Cranichideae in the subtribe Spiranthinae . The genus was described by Richard in 1817 , according to other sources, by Lindley in 1826 - Lindley had already used the name Collea in 1823 . The name comes from the Greek word pelex for "helmet". The type species is Pelexia adnata , which was named Satyrium even before Richard's publication of the new genus .

Burns-Balogh grouped the genera Pelexia , Cyclopogon and Sarcoglottis to the " Pelexia alliance", later summarized by Szlachetko in a separate subtribe Cyclopogoninae. According to DNA studies, however , Pelexia is closely related to Odontorrhynchus and possibly Sauroglossum .

Pelexia bonariensis
Illustration of Pelexia gutturosa (Fig. III, right)
Pelexia laxa
Illustration of Pelexia macropoda (Fig. I, right) and Pelexia hysterantha (Fig. II, left)
Illustration of Pelexia parva (Fig. II, left)
Illustration of Pelexia ventricosa (Fig. I, left)

The following species are included in the genus Pelexia :

literature

  • Leslie A. Garay: 225 (1). Orchidaceae (Cypripedioideae, Orchidoideae and Neottioideae) . In: Gunnar Harling, Benkt Sparre (ed.): Flora of Ecuador . tape 9 , 1978, ISSN  0347-8742 , p. 246-247 .
  • Leslie A. Garay: A generic revision of the Spiranthinae . In: Botanical Museum Leaflets of Harvard University . tape 28 , no. 4 , 1982.
  • Alec M. Pridgeon, Phillip Cribb, Mark W. Chase, Finn Rasmussen (Eds.): Genera Orchidacearum. Orchidoideae (Part 2). Vanilloideae . tape 3 . Oxford University Press, New York and Oxford 2003, ISBN 0-19-850711-9 .

Individual evidence

  1. ↑ a b Leslie Garay: Pelexia . In: A generic revision of the Spiranthinae . Pp. 342-343.
  2. ↑ a b c d e Gerardo Salazar: Pelexia . In: Genera Orchidacearum . Vol. 3, pp. 232-236.
  3. ^ Robert L. Dressler: Phylogeny and Classification of the Orchid Family . Cambridge University Press, 1993, ISBN 0-521-45058-6 , pp. 120 .
  4. ↑ Rodrigo B. Singer, Marlies Sazima: The pollination mechanism in the 'Pelexia alliance' (Orchidaceae: piranthinae) . In: Botanical Journal of the Linnean Society . tape 131 , 1999, pp. 249-262 ( sazima.org [PDF]).
  5. ↑ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi bj bk bl bm bn bo bp bq br bs bt bu bv bw bx by bz ca cb cc cd ce cf cg ch ci cj ck cl cm cn Rafaël Govaerts (Ed.): Pelexia. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved March 30, 2020.

Web links

Commons : Pelexia  - album with pictures, videos and audio files