Spiranthes × Zahlbruckneri

''Spiranthes'' is a genus of orchids in the subfamily Orchidoideae. They are known commonly as ladies tresses, ladies'-tresses, or lady's tresses.''Spiranthes''.
Integrated Taxonomic Information System (ITIS). The genus is distributed in the Americas, Eurasia, and Australia.''Spiranthes''.
Flora of North America. The genus name ''Spiranthes'' is derived from the Greek ''speira'' ("coil") and ''anthos'' ("flower"), and was inspired by the spirally arranged inflorescence.

Description

These are perennial herbs growing from fleshy root systems that range from slender to tuberous, and are occasionally stoloniferous. 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 characteristic 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 thin to somewhat fleshy, and two basal glands produce nectar. The flowers are usually white, cream, ivory, or yellowish, and two species have pink flowers; a few are also fragrant.''Spiranthes''.
The Jepson eFlora 2013.

Taxonomy and naming

The genus ''Spiranthes'' was first formally described in 1817 by Louis Claude Richard in his book ''De Orchideis Europaeis Annotationes''. The genus's name is derived from ancient Greek words meaning "a coil" and "a flower".

Since its original description, the genus has undergone many taxonomic changes. ''Spiranthes'' once contained all the species from the subtribe Spiranthinae. In 1920, ''Spiranthes'' was split into 24 genera. Revisions in 1951 and 1958 placed more species into the genus. During the 1990s it was divided again.

''Spiranthes'' has recently received increased attention from taxonomists and systematists, leading to new species discovery and the resolution of many long-term taxonomic questions.

It is difficult to clearly define some of the species of this taxon because some of them are polymorphic, taking a number of different forms,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. with some species belonging to species complexes involving several closely related and morphologically similar species (e.g., the ''S. cernua'' species complex; ''S. parksii'', a member of the ''S''. ''cernua'' complex and probably a descendant of ''S. cernua''. It has been suggested that this species is just another rare form).

Species list

The following is a list of species accepted by the World Checklist of Selected Plant Families as at May 2020:
* '' Spiranthes aestivalis'' (Poir.) Rich. (1817) – summer-flowering spiranthes (western & central Europe to northwestern Africa)
*''Spiranthes arcisepala'' M.C. Pace (2017) – Appalachian ladies'-tresses (Northeastern US & Maritime Canada)
* ''Spiranthes australis'' ( R.Br.) Lindl. – Austral ladies tresses (southern Caspian Sea and Himalayan Mountains to the South-West Pacific)
*''Spiranthes bightensis'' M.C. Pace (2021) – Atlantic ladies'-tresses ( Mid-Atlantic USA)
* ''Spiranthes brevilabris'' Lindl. (1840) – Texas ladies'-tresses (southeastern USA)
* ''Spiranthes casei'' Catling & Cruise (1974) – Case's ladies'-tresses (eastern Canada & USA)
** ''Spiranthes casei'' var. ''casei''
** ''Spiranthes casei'' var. ''novaescotiae'' Catling (1981) (Nova Scotia)
* ''Spiranthes cernua'' (L.) Rich. (1817) – nodding ladies'-tresses (eastern Canada & USA)
* ''Spiranthes delitescens'' Sheviak (1990) – reclusive ladies'-tresses (Southeastern Arizona)
* ''Spiranthes diluvialis'' Sheviak (1984) – Ute's ladies'-tresses (Rocky Mountains USA)
* ''Spiranthes × eamesii'' P.M.Br. (North-eastern U.S.A.)
* '' Spiranthes eatonii'' Ames ex P.M.Br. (1999) – Eaton's ladies'-tresses (southeastern USA)
*''Spiranthes flexuosa