Spiranthes

Spiranthes
Spiranthes spiralis
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Monocots
Order: Asparagales
Family: Orchidaceae
Subfamily: Orchidoideae
Tribe: Cranichideae
Subtribe: Spiranthinae
Genus: Spiranthes
Rich., 1817
Type species
Ophrys spiralis = Spiranthes spiralis
(L.) Chevall. 1827
Species

See text.

Spiranthes is a genus of orchids in the subfamily Orchidoideae. They are known commonly as ladies tresses, ladies'-tresses, or lady's tresses.[1] The genus is distributed in the Americas, Eurasia, and Australia.[2] The genus name Spiranthes is derived from the Greek speira ("coil") and anthos ("flower"), and was inspired by the spirally arranged inflorescence.[2]

Description

These are perennial herbs growing from fleshy root systems that are sometimes thick and appear tuberous. Most of the leaves are basal, but some species have leaves higher on the stem before the inflorescence matures, often taking the form of a sheath around the stem. The inflorescence is a terminal spike with flowers arranged in a loose or dense spiral. As in most other orchids, the flowers are resupinate, twisting during development into an upside-down position. The six tepals may be separate, or the three upper may be joined to form a hood over the lip petal. The lip is pouched and is thin to somewhat fleshy. The flowers are usually white, cream, or yellow, and at least one species has pink flowers.[2][3]

Systematics

Diversity

Spiranthes romanzoffiana

There are about 42[4] to 45[2] species in the genus.

Species include:[1][2][5][6]

Hybrids include:

Taxonomy

This genus has undergone many taxonomic changes. Spiranthes once contained all the species from the subtribe Spiranthinae. In 1920, Spiranthes was split into 24 genera.[9] Revisions in 1951[10] and 1958[11] placed more species into the genus. During the 1990s it was divided again.[12]

It is difficult to clearly define the species of this taxon because some of them are polymorphic, taking a number of different forms.[13] There is a species complex involving S. cernua, a "facultatively agamospermic polyploid compilospecies"[14] which takes many forms that appear well-separated at times and have been mistaken for new species. An example might be S. parksii, a member of the complex and probably a descendent of S. cernua. It has been suggested that this species is just another rare form.[15][13]

References

  1. 1 2 Spiranthes. Integrated Taxonomic Information System (ITIS).
  2. 1 2 3 4 5 Spiranthes. Flora of North America.
  3. ↑ Spiranthes. The Jepson eFlora 2013.
  4. ↑ Spiranthes. New South Wales Flora Online. National Herbarium, Royal Botanic Garden, Sydney.
  5. ↑ GRIN Species Records of Spiranthes.
  6. ↑ Spiranthes. USDA PLANTS.
  7. ↑ Sheviak, C. (1990). A new Spiranthes (Orchidaceae) from the cienegas of southernmost Arizona. Rhodora 92 213–31.
  8. 1 2 Spiranthes. Flora of China.
  9. ↑ Schlechter, R. (1920). Versuch einer systematischen Neuordnung der Spiranthinae. Beih. Bot. Centralbl. 37 317–454. (in German)
  10. ↑ Williams, L. O. The Orchidaceae of Mexico - 4 Volumes. Ceiba Tegucigalpa. 1951.
  11. ↑ Schweinfurth, C. Orchids of Peru. Fieldiana Bot. 30 1–260. 1958.
  12. ↑ Szlachetko, D. L. (1996). Studies on Spirantheae Orchidaceae: I. Varia. Fragmenta Floristica et Geobotanica 41(2), 845-63.
  13. 1 2 Dueck, L. A. and K. M. Cameron, K. M. (2007). Sequencing re-defines Spiranthes relationships, with implications for rare and endangered taxa. Lankesteriana 7(1-2), 190-95.
  14. ↑ Spiranthes cernua. Flora of North America.
  15. ↑ Spiranthes parksii. Flora of North America.

External links

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