Spiranthes longilabris
Spiranthes parksii
giantspiral ladiestresses, giantspiral lady's tresses, longlip lady's tresses
Navasota lady's tresses
numerous, mostly to 1 cm diam., stout.
few, spreading to descending, slender to somewhat tuberously thickened, mostly to 0.8 cm diam.
fugacious or persisting through anthesis, to 3–5, cauline, reduced to sheathing bracts upward on stem, spreading, linear-lanceolate, keeled, 5–15 × 0.5 cm, rigid.
fugaceous, basal, ascending to spreading, linear-lanceolate to somewhat broader.
spikes loosely to tightly spiraled, usually no more than 180°, 5–9 flowers per cycle of spiral, sometimes secund;
rachis sparsely pubescent, some trichomes capitate, glands obviously stalked.
loosely spiraled, usually 5 flowers per cycle of spiral;
rachis moderately to densely pubescent, some trichomes capitate, glands obviously stalked.
mostly horizontal, strongly gaping, white to cream;
sepals distinct to base, lanceolate, tapering in distal 1/3, (8–)9–10 × 2–3 mm;
lateral sepals widely spreading;
petals linear, slightly falcate, 7–9 × 2–2.5 mm;
lip yellow centrally, ovate in general outline, base rounded-dilated, apical portion descending, oblong, 8–11 × 4 mm, apex recurved with margin crisped;
basal calli erect, tapered, to 1 mm;
viscidium linear-lanceolate;
ovary mostly 7 mm.
horizontal to ascending, white to pale yellowish green, scarcely gaping, urceolate-tubular;
sepals distinct to base, 5–8 mm;
lateral sepals directed nearly forward, apex straight or apical 1–2 mm curved upward;
petals whitish to yellow-green with longitudinal central green stripe, ovate, obovate, or suborbiculate, 4.5–6.7 mm, apex obtuse to emarginate-erose;
lip centrally yellow to yellowish or greenish white, ovate to ovate-oblong, 5–7 × 3.8–4.9 mm, apex truncate, obtuse to deeply emarginate, erose-crisped, glabrous;
veins several, branches parallel;
basal calli incurved to elongate, prominent;
viscidia linear-lanceolate;
ovary 4–6 mm.
monoembryonic.
partly or wholly polyembryonic.
= 60.
Spiranthes longilabris
Spiranthes parksii
Hybrids of Spiranthes longilabris and S. odorata are known as Spiranthes ×folsomii P. M. Brown.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
The tetraploid chromosome number and apomictic development of polyembryonic seeds indicate that Spiranthes parksii is a member of the S. cernua complex. The broad petals with central green stripe, several veins (instead of the three typical of the group), and erose-emarginate apical margin furthermore evidently represent partial peloria. Peloria is common in S. cernua, especially in the prairies, although in most cases it involves the suppression of the lip rather than the elaboration of the petals to a condition approximating the lip, as is the case in S. parksii. With a very limited distribution in east-central Texas, S. parksii might therefore represent merely a local, minor form of S. cernua. Other characteristics, however, including the small flower size and often upturned lateral sepal apices, lie outside the normal range of variation in S. cernua and suggest that the plants represent a distinct species.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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