Taxonomy
 

Classification

Spiranthes parksii is a rare orchid endemic to Texas. In 1947, Donovan Correll was annotating herbarium specimens at Texas A&M University when he noticed that some material, labeled S. gracilis, appeared unique (Luer, 1975). He described the plant as a new species, naming it in honor of its collector, Dr. H.B. Parks.  In 1978, the S. parksii was "rediscovered," prompting further study. Because members of the genus Spiranthes provide taxonomic confusion, questions arose as to whether or not S. parksii was actually a distinct species and not just a subspecies or variety of another similar plant, S. cernua. In 1986, Dr. Charles Sheviak confirmed that S. parksii was indeed a separate biological species.
 
Morphology
S. parksii is an erect perennial orchid, approximately 8-15 inches (~2-3 dm) tall. The leaves are linear and usually not present by flowering time which occurs in late October to early November, although research has suggested that not all plants flower annually (U.S. Fish and Wildlife Service, 1993). The flowers are cream-colored and loosely spiral around the stem. The side petals have a green central stripe, and the bracts, located directly below the flower, have pointed, white tips. According to Correll (1970), "the characteristically obovate petals and oval lip are distinctive and conveniently separate this species from all other species of Spiranthes found in Texas." Thus, in the non-flowering condition, S. parksii is indistinguishable from intraspecific types. Similar species with key character differences are noted below (Poole & Riskind, 1987):

Flowers in tighter spiral up the stem, usually white;
bracts below flowers not white-tipped.................................................. S. cernua

Lower petal (lip) with green central stripe............................................ S. gracilis var. gracilis
 
 
Spiranthes cernua Spiranthes gracilis
 


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