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Published In: Botanical Museum Leaflets 23(7): 287–297, pl. 22. 1973. (Bot. Mus. Leafl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 7/9/2009)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Native

 

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4. Spiranthes magnicamporum Sheviak (Great Plains ladies’ tresses)

Pl. 117 c, d; Map 484

Flowering stems 10–50(–60) cm long, with sparse to dense, glandular hairs. Basal leaves 3 or 4, absent at flowering time, 5–14 cm long, linear, glabrous. Flowers appearing as though in 2 or more ranks or intertwined spirals along the flowering stems or sometimes no spirals discernable. Sepals and lateral petals 7–11 mm long, white, the lateral sepals free to the base or nearly so, spreading, the tips arching upward and angling away from the rest of the perianth. Lip 8–10 mm long, ovate to oblong, the margins somewhat irregular toward the tip, white, tinged with light yellow to yellowish tan in the middle of the inner surface. Column 4 mm long, green. 2n=30. September–November.

Scattered in the Ozark and Ozark Border Divisions (New Mexico to Georgia north to North Dakota, Pennsylvania, and adjacent Canada). Dolomite glades, less commonly in openings of dry upland forests, in fens, and on limestone glades.

Elsewhere, this species occurs primarily in dry prairies on calcareous soils. Although many of the upland prairies in Missouri’s Unglaciated Plains Division are on soils derived from sandstone substrates, this species eventually may be found in some of the remaining dry dolomite prairies. It may have been more common in this part of the state prior to the plowing of most of the prairie landscape for conversion to agriculture.

Spiranthes magnicamporum is a diploid, sexual member of the S. cernua complex and was not distinguished from that species prior to 1973. Earlier reports of S. ochroleuca (Rydb.) Rydb. (S. cernua (L.) Rich. var. ochroleuca (Rydb.) Ames) from Missouri are also referrable to S. magnicamporum Sheviak (Sheviak and Catling, 1980), and that taxon occurs only to the northeast of the state.

Much of the difficulty in distinguishing between S. magnicamporum and S. cernua is because of the great morphological variation in the latter taxon. However, several subtle characters separate the two. The flowers of S. cernua usually have only a faint, sweet fragrance. The perianth is narrowly urn‑shaped, arching gently with an even curve throughout its length, the lip curving outward abruptly from the rest of the perianth about a third of the way from the tip and the lateral sepals only slightly spreading, thus oriented parallel to the rest of the perianth. The flowers of S. magnicamporum have a strong, sweet fragrance of coumarin, an unsaturated lactone that is responsible for the aroma of freshly cut hay. The perianth is broadly urn‑shaped, curving mostly near the base, with the lip still diverging from the upper sepal and lateral petals about a third of the way from the tip. However, the lateral sepals curve only slightly at the base and are otherwise nearly straight, the tips arching inward and slightly upward above the upper sepal and lateral petals, thus angled away from the plane of the rest of the perianth.

 


 

 
 
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