Amitostigma

无柱兰属
wu zhu lan shu
Amitostigma keiskei
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Orchideae
Subtribe: Orchidinae
Alliance: Orchis
Genus: Amitostigma
Schltr. 1919
Species

See text.

Amitostigma is a genus in the orchid family (Orchidaceae).[1] It is an exclusively Asian genus of 28 orchids, growing in the alpine habitats of China, Japan, Korea, Vietnam, Thailand and the Kuril Islands.[2] Twenty two species of this genus grow in China.[3]

Amitostigma are dwarf terrestrial orchids, including some myco-heterotrophic species. The globose or ovoid tubers (1 to 1.5 centimetres) of these autotrophic plants are fleshy and not lobed, with several slender roots. New shoots grow each tuber.

The stem is usually erect, with one (or rarely two or three) basal or cauline (stem) leaves. The length of the stem can vary between 5 and 45 centimetres.

The green leaf blade is not articulate and can have an oblong, lanceolate, elliptic, or ovate form, even within the same species (see A. lepidum). The leaves appear at the time of expansion of the flower (anthesis).

The terminal inflorescence is racemose, seldom subcapitate. The floral bracts are often lanceolate. The cylindrical to fusiform ovary is resupinate (turned upside down).

Each inflorescence shows many (rarely one or two) flowers. These are also resupinate and usually twisted to one side.

The sepals are completely separate from each other, with an oblong to ovate appearance, and usually singly veined. The erect petals are straight, often slightly broader than the sepals. The three- or four-lobed lip is usually longer and broader than the petals and sepals, spurred at the base. The mid-lobe is oblong, square, or ovate. The margin of the lip is often slightly undulate.

They have a characteristic short column. The erect anthers are cohesive with the column through its broad base or back. They have two parallel locules with farinaceous, sectile pollinia. The small rostellum is beak-shaped, attached with its folded end to the viscidium. The two protruding stigmas are slightly club-shaped.

The capsule is suberect.

The color may vary within the same species: Amitostigma lepidum may show a purple lip with white margins, or a white lip with purple dots or a totally white lip. Even the leaves may vary from lanceolate to ovate within the same species.

After flowering, the leaves turn yellow color and die off. The plants then starts its summer dormancy for several months. This cycle is well adapted to a climate which is hot and dry in summer.

Species

Species recognized as of May 2014:[2]

  1. Amitostigma alpestre Fukuy. (1935) - Taiwan
  2. Amitostigma amplexifolium Tang & F.T. Wang (1936) - Sichuan
  3. Amitostigma basifoliatum (Finet) Schltr. (1919) - Sichuan, Yunnan
  4. Amitostigma bidupense (Aver.) Aver., Turczaninowia 13(2): 19 (2010) - Vietnam
  5. Amitostigma bifoliatum Tang & F.T. Wang (1936) - Sichuan, Gansu
  6. Amitostigma capitatum Tang & F.T. Wang (1936) - Sichuan, Hubei
  7. Amitostigma dolichocentrum Tang, F.T. Wang & K.Y. Lang (1982) - Sichuan
  8. Amitostigma faberi (Rolfe) Schltr. (1919) - Sichuan, Yunnan, Guizhou
  9. Amitostigma farreri Schltr. (1924) - Tibet, Yunnan
  10. Amitostigma gonggashanicum K.Y. Lang (1984) - Sichuan
  11. Amitostigma gracile (Blume) Schltr. (1919) - Japan, Korea, Anhui, Fujian, Guangxi, Guizhou, Hebei, Henan, Hubei, Hunan, Jiangsu, Liaoning, Shaanxi, Shandong, Sichuan, Taiwan, Zhejiang
  12. Amitostigma hemipilioides (Finet) Tang & F.T.Wang (1936) - Yunnan, Guizhou
  13. Amitostigma keiskei (Finet) Schltr. (1919) - Japan
  14. Amitostigma keiskeoides (Gagnep.) Garay & Kittr. (1985) - Vietnam
  15. Amitostigma kinoshitae (Makino) Schltr. (1919) - Kuril Islands, Japan
  16. Amitostigma lepidum (Rchb.f.) Schltr. (1919) - Kyushu, Ryukyu Islands
  17. Amitostigma monanthum (Finet) Schltr. (1919) - Tibet, Gansu, Shaanxi, Sichuan, Yunnan
  18. Amitostigma papilionaceum Tang, F.T. Wang & K.Y. Lang (1982) - Sichuan
  19. Amitostigma parciflorum (Finet) Schltr. (1919) - Sichuan, Chongqing
  20. Amitostigma physoceras Schltr. (1924) - Sichuan
  21. Amitostigma pinguicula (Rchb.f. & S. Moore) Schltr. (1919) - Zhejiang
  22. Amitostigma simplex Tang & F.T. Wang (1940) - Sichuan, Yunnan
  23. Amitostigma tetralobum (Finet) Schltr. (1919) - Sichuan, Yunnan
  24. Amitostigma thailandicum Seidenf. & Thaithong (1997) - Thailand
  25. Amitostigma tibeticum Schltr. (1924) - Tibet, Yunnan
  26. Amitostigma trifurcatum Tang, F.T. Wang & K.Y. Lang (1982) - Yunnan
  27. Amitostigma wenshanense W.H. Chen, Y.M. Shui & K.Y. Lang (2003) - Yunnan
  28. Amitostigma yuanum Tang & F.T. Wang (1940) - Tibet, Yunnan

References

  1. ↑ Schlechter, Friedrich Richard Rudolf, 1919. Repertorium Specierum Novarum Regni Vegetabilis, Beihefte 4: 91–92
  2. 1 2 Kew World Checklist of Selected Plant Families
  3. ↑ Flora of China v 25 p 124, 无柱兰属 wu zhu lan shu, Amitostigma
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