Epidendrum
| Epidendrum | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Epidendrum nocturnum |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Epidendrum | ||||||||||||
| L. |
The genus Epidendrum from the family of the orchid (Orchidaceae) comprises more than 1660 plant species that are found in South and Central America. Most of them are evergreen, perennial , epiphytic plants. They represent a significant part of the neotropical orchid flora.
description
The species of the genus Epidendrum form sprouts with limited growth ( sympodium ) at intervals on a creeping rhizome . Some species grow monopodially . The stem axis is often long, slender and its proportions are reminiscent of a reed or bamboo stalk. Occasionally it is also thickened in the shape of a cigar or shaped into round pseudobulbs . The roots arise from the rhizome, more rarely along the stem axis, they are smooth and fleshy, surrounded by a velamen about three to seven cell layers thick .
The leaves sit in two rows on the shoot, depending on the species, there is only one leaf per shoot or it is densely leafed. The leaf base encloses the shoot in a tubular shape. There is usually a separating fabric between the leaf and the leaf base. The leaf shape varies from linear to lanceolate to broad-oval. The leaves are often leathery and firm, but sometimes paper-like, thin or fleshy, thickened to petal-round. Some species have reddish markings on the otherwise green leaves. Both sides or just the underside of the leaf are covered with trichomes .
.jpg)
The inflorescence often appears from a flower sheath at the tip of the shoot. But there are also species with lateral inflorescences or the rhizome alternately bears a leafy and a flowering shoot. Species that grow monopodially form the inflorescence mostly laterally, but also monopodially growing species with terminal inflorescence and thus limited lifespan of the plant ( semelparitia ) occur. The shape of the inflorescence ranges from single-flowered to umbels and panicles , and occasionally another flower shoot develops from one inflorescence in the next growing season. The flowers are not always resupinated , they are spirally or two-lined on the flower stem. The most common flower color is light green to white, except blue but also all other colors. The flowers often produce fragrance, often only at certain times of the day. The sepals and petals are not grown together and are usually wide open. The inner petals look similar to the outer three, they are usually narrower, in some species only thread-shaped. The lip is fused with the edges of the column along its entire length, less often partially or completely free. Lip and column so as to form a tube, this Nectary continues in the up ovary continued. The lip is simple or three to four-lobed. There is often a callus in the middle of the lip . The column is straight or curved, seldom forms a columnar foot or a sack-like protuberance at the base together with the lip. The stamen sits on top or at the end of the column and contains two or four pollinia . Two stems are joined together to form a pair. The scar has a central and two distinct side lobes. The rostellum is slit-shaped along the column, it produces a semi-liquid adhesive (viscidium).
The fertilization is performed by insects that try to pass through the lip-column tube to the nectar (keyhole flower) while pollinia transferred get stuck or stuck to them pollinia on the stigma. The few pollinators that could be observed were mostly butterflies or moths, but bees, flies, wasps and, in some species, hummingbirds are also responsible for pollination. Many species do not produce any nectar at all and deceive the flower visitors .
The capsule fruit is oval, sometimes pear-shaped or almost round. The seeds are numerous and small, 500 to 1000 microns in diameter. There are also species whose seeds have appendages up to six millimeters in size, making them one of the largest orchid seeds.
As far as is known, the number of chromosomes is usually 2n = 40.
Distribution and locations
The species of the genus Epidendrum are native to almost the whole of the Neotropic. The northernmost occurrences are with Epidendrum magnoliae in the subtropical southeast of the USA, in the south Argentina is reached. The evolutionary origin of the genus could be in Central America, because representatives of practically all intrageneric groups occur there.
Most of the species are epiphytes of humid or seasonally dry forests. Different species have specialized in colonizing branches inside the canopy, in the outer, sunny area of the treetop or on the trunk. There are only two epiphytes in the genus. Some species live in accumulations of humus in forks of branches or are preferably found in the nests of tree-dwelling ants. Representatives of this genus are also found in plantations and orchards. Although the greatest biodiversity can be found in damp cloud forests, there are various adaptations to dry growing habitats: deciduous species as well as those with succulent leaves or sprouts.
Terrestrial locations are populated by fewer species. There are specialists for extremely rudderal locations that occur on landslides, sand dunes or roadsides. These species bloom after a year or two before they are displaced by higher vegetation. Further terrestrial epidendrum species can be found in the grasslands of the Andes (Páramos) or on the table mountains called Tepui .
Systematics
Within the subfamily Epidendroideae , the genus Epidendrum is classified in the tribe Epidendreae and there in the subtribe Laeliinae . Epidendrum is closely related to Barkeria , Caularthron and Orleanesia .
A list of the recognized species can be found in R. Govaerts.
Botanical history
Carl von Linné named all epiphytic orchids known to him Epidendrum , which means something like "on the tree". The species named by Linné are today counted among the most diverse genera.
Individual evidence
- ^ Cássio van den Berg, Mark W. Chase: A reappraisal of Laeliinae. Taxonomic history, phylogeny and new generic alliances. ( Memento of the original from September 26, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. In: Orchid Digest. San Marino CA 4.2004, 221-225. ISSN 0199-9559
- ↑ Rafaël Govaerts (ed.): Epidendrum. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved April 6, 2020.
literature
- Alec M. Pridgeon, Phillip Cribb, Mark W. Chase: Genera Orchidacearum . Vol. 4/1. Epidendroidae (Part one). Oxford University Press, New York 1999. ISBN 0-19-850712-7
Web links
- Rafaël Govaerts (Ed.): Epidendrum. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew .