Spiranthes casei Catling & Cruise

Case's ladies'-tresses

The specific epithet casei honors Fred Case, author of "Orchids of the Western Great Lakes Region."

DESCRIPTION: Plant pubescent with capitate hairs above the leaves, 14-38 cm tall (including inflorescence), arising from a cluster of fleshy, slender roots. Leaves 2-3(-5), lowermost ovate-lanceolate and forming a loose basal rosette, 7-10 cm long and 1-2 cm wide, fugacious (withering at flowering), upper leaves persistent, linear-lanceolate to oblanceolate, 10-20 cm long and 0.5-1 cm wide, grading into reduced sheathing bracts below the inflorescence. Inflorescence a downy, loose spicate raceme of 20-40 cream-colored flowers, 14-38 cm tall, typically forming a loose single spiral, each flower subtended by an elongate, ovate-lanceolate bract. Sepals lanceolate, 5-7 mm long and about 2 mm wide, the lateral sepals with margins inrolled, and appressed to the labellum, dorsal sepal connivent with petals to form a hood over the column, sepals creamy-white to cream colored. Petals lanceolate to oblanceolate, 5-7 mm long and 1-2 mm wide, closely appressed to the dorsal sepal, tips of dorsal sepal and petals reflexed slightly, colored as sepals. Labellum ovate, 5-6.5 mm long and 3.5-5 mm wide, apex bent downwards, creamy-white to cream colored, base of the labellum with two short, pubescent calli.

Easily confused with other species of Spiranthes, particularly S. cernua and S. magnicamporum. The spreading lateral sepals, leafless stem at flowering and odor of S. magnicamporum separate it from S. casei, which has appressed lateral sepals, a leafy stem at anthesis and scentless flowers. Separating S. cernua from S. casei is more difficult. The closely appressed lateral sepals of S. casei and its creamy color differ from the more spreading sepals and white color of S. cernua. In overall appearance, the flowers of S. cernua appear larger and more open than those of S. casei. Finally, the inflorescence of S. casei is nearly always loosely single-ranked, whereas the inflorescence of S. cernua is usually multi-ranked and frequently densely so.

Spiranthes casei is usually found in dry, sandy, sterile sites. Common habitats include the tops of sandstone bluffs, and sandy jack-pine barrens. There is one collection from a wet ditch in sandy soil.

August 8-September 26, with a peak of records from the last week of August.

Catling (1983b) collected a halictid bee (Dialictus versans) pollinating Spiranthes casei in Ontario. It is likely that halictid bees or bumblebees also pollinate S. casei in Wisconsin.

DISCUSSION: A specimen of Spiranthes casei apparently collected by Umbach August 23, 1900 at Devil's Lake was initially confused with S. lucida, because of its wide basal leaves (typical of S. casei, but S. lucida is also characterized by wide leaves). Fuller (1933) examined the specimen and decided that it represented a wide-leaved form of S. cernua, missing the differences that separate this taxon from S. cernua. Some 40 years later, Catling & Cruise (1974) described S. casei. This specimen is one of the earliest collections of this species.

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