Spiranthes

Scientific name

Spiranthes Rich.

Common names

lady's-tresses, ladies tresses

Family

Orchidaceae

Similar genera

Habenaria

Native distribution

temperate and tropical regions of the World; maximum diversity in North America

Species cultivated

Spiranthes cernua (L.) Rich.

S. graminea Lindl.

S. odorata (Nutt.) Lindl.

Adventive distribution

information not available

Weed status

not weedy

Habit

amphibious herbs, some tolerant of short periods submerged

Brief description

Medium to large orchid. Roots slender to tuberously thickened, fleshy, spreading to descending. Stem erect, slender. Leaves basal, occasionally attached to proximal portion of stem, alternate, ascending to spreading; sessile to petiolate; leaf blade linear, ovate, elliptic to oblanceolate; apex acute or acuminate. Inflorescence an erect spike, loosely to tightly spiraled; rachis glabrous to variously pubescent; bracteoles ovate to lanceolate, apex acuminate. Flowers small, mostly ascending, tubular, white to cream, yellowish, or pink, ± fragrant; sepals free or connate, elliptic, linear to oblanceolate, glabrous to pubescent outside, dorsal sepal often fused with petals and forming a hood, lateral sepals ± spreading or appressed to petals; petals linear to ovate, oblong, apex acute to obtuse, ± spreading; spur absent. Labellum lanceolate to ovate, oblong, or ± rectangular, middle often constricted; entire or shallowly 3-lobed; base typically with calli; apex acute to obtuse, ± recurved; apical margin typically crenulate or lacerate; glabrous or distally granular; often yellow to orange centrally. Fused stamens and carpels erect, fleshy; pollinia 2, yellow, viscidia usually linear to linear-lanceolate.

Natural habitat

in and along continuously or intermittently inundated habitats; fens, marshes, swamps, bogs, wet grasslands and meadows, stream banks

Additional comments

Spiranthes contains approximately 40 species, most of which are amphibious. It is one of the most widely distributed genera of orchids. Spiranthes odorata is often offered as an aquarium plant, where it thrives better if emersed in wet ground and not fully submerged.