Arundina graminifolia
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| ( D.Don ) Hochr. |
Arundina graminifolia is a species in the orchid genus Arundina . It is unclear whether other described taxa deserve the species rankin this genus. The quite large plants have a wide distribution area in Southeast Asia. They are widespread as an ornamental plant in the tropics and naturalized in several places.
description
According to the large distribution area, there is a large range of variation in the characteristics. A subdivision into several types fails because of the flowing transitions that do not allow a clear distinction.
The roots emerge from an underground rhizome and are surrounded by a two-layer velamen . The close together rungs reach a length of 30 to 300 centimeters. They are densely covered with two-line leaves and can be branched in the upper part. The leaves are linear and their base encompasses the stem, which is completely covered by leaf bases. The length of the leaves is usually 15 to 30 centimeters with a width of 0.75 to 2.5 centimeters. However , the forms of Ceylon known as Arundina minor have leaves that are only 5 to 7.5 cm long and 4.5 to 6 mm wide.
The racemose , rarely branched, inflorescence reaches about 40 centimeters in length and bears up to 15 resupinated flowers . They bloom one after the other so that only one or two flowers are open at a time. The flower color is pink to white. The diameter of the flowers is three centimeters in the smallest forms and can reach up to twelve centimeters. The sepals are elongated-oval to lanceolate, pointed, the two lateral ones point downwards so that, viewed from the front, they stand behind the lip . The petals are about twice as wide as the outer petals, also pointed and horizontal. The elongated oval lip is darker in color than the other petals, in the middle is a yellow spot with three comb-like, hairy keels. At the base of the lip it is turned up and encircles the column . The edge is wavy, the lip is slightly incised at the tip. The column is winged on the side. The stamen contains eight soft pollinia .
Self-pollination occurs in some populations. Pollination by bees of the genus Xylocopa has been reported in others .
The number of chromosomes is given by various authors as 2n = 40, 2n = 32 or 2n = 42.
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distribution
Arundina graminifolia grows widespread in Southeast Asia. The area extends from the southern edge of the Himalayas in Tibet, Bhutan and India through southern China, the Ryūkyū Islands , all of Indochina , to Indonesia (Sumatra, Java, Kalimantan, Sulawesi). A disjoint area is located in southern India and Sri Lanka. It was introduced and naturalized as an ornamental plant in the Philippines, Hawaii, Venezuela and Trinidad.
The locations are sunny places, for example forest clearings caused by disturbances or on steep, rocky slopes. The climate is characterized by a short dry period. Due to human activity, the available locations have expanded, so today this species is often found on roadsides and embankments.
Taxonomy and systematics
The generic name Arundina comes from the Latin “arundo”, which means “reed” and refers to the similarity of the growth habit. The specific epithet graminifolia , "grass-leaved", refers to the shape of the leaves.
In the genus more than two dozen taxa have been described on species level, which are now mostly treated as synonyms of Arundina graminifolia . However, in 2007 the Russian orchids specialists Averyanov with Arundina caespitosa a new diminutive species from Vietnam have been described. This author also accepts Arundina minor , also a small species from Ceylon, as an independent species. In contrast, the authors of the "Flora of China" prefer a broad species concept according to which Arundina graminifolia is the only species in the genus and includes all these taxa .
Within the subfamily Epidendroideae , the genus Arundina is classified in the tribe Arethuseae and there in the subtribe Arethusinae . The related genus Anthogonium is also found in Southeast Asia ; the other genera in this subtribe ( Arethusa , Calopogon and Eleorchis ) are distributed further north in a temperate climate.
According to R. Govaerts, the following subspecies can be distinguished:
- Arundina graminifolia subsp. caespitosa (Aver.) HAPedersen & Schuit. : It occurs from Assam to Malesia and in Sri Lanka.
- Arundina graminifolia subsp. graminifolia : It occurs in tropical and subtropical Asia.
literature
- Jim B. Comber (1990): Orchids of Java . P. 87f. Bentham-Moxon Trust, RBG Kew. ISBN 0-947643-21-4
- Alec M. Pridgeon, Phillip Cribb, Mark W. Chase: Genera Orchidacearum . Vol. 4/1: Epidendroidae (Part one) . Pp. 18-22. Oxford University Press, 2005. ISBN 0-19-850712-7
Individual evidence
- ↑ Jayaweera DMA 1981: Orchidaceae. In: Dassanayake MD, Fosberg FR (eds.): A revised handbook to the Flora of Ceylon. Vol. II. Pp. 4-386. Oxford & IBH Publishing Co., New Delhi, Bombay, Calcutta.
- ↑ a b c d Rafaël Govaerts (Ed.): Arundina. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved July 6, 2018.
- ^ Averyanov LV 2007: New Species of Orchids from Vietnam. Taiwania 52: 287-306. - online
- ^ Chen Xinqi & Gale SW 2009: Arundina. In: Flora of China. Vol. 25. pp. 314-315. Science Press, Beijing, Missouri Botanical Garden Press, St. Louis. - Arundina graminifolia - Online. (engl.)
