Spiranthes magnicamporum Sheviak

Great Plains Ladies' Tresses


CC = 7
CW = 3
MOC = 33

© SRTurner

Family - Orchidaceae

Habit - Perennial forb, lacking rhizomes.

Stem - Erect, to 50 cm, unbranched, with sparse to dense, glandular hairs.

Spiranthes_magnicamporum_base.jpg Base of plant.

© SRTurner

Spiranthes_magnicamporum_stem.jpg Stem and nodes.

© SRTurner

Leaves - Basal leaves 3 or 4, absent at flowering time, 5-14 cm long, linear, glabrous. Stem leaves alternate, reduced to small sheathing bracts.

Spiranthes_magnicamporum_stem2.jpg Stem and leaves.

© SRTurner

Inflorescences - Dense terminal spikes, the flowers sessile and spirally arranged, usually appearing as though in 2 or more ranks or intertwined spirals along the flowering stems.

Spiranthes_magnicamporum_inflorescence.jpg Inflorescence.

© SRTurner

Flowers - Fragrant. 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. Stamen 1.

Spiranthes_magnicamporum_flowers1.jpg Flowers, frontal view.

© SRTurner

Spiranthes_magnicamporum_flowers2.jpg Flowers, lateral view.

© SRTurner

Spiranthes_magnicamporum_flowers3.jpg Flowers. Note spreading and arching habit of lateral sepals.

© SRTurner

Spiranthes_magnicamporum_flowers4.jpg Flowers, top view.

© SRTurner

Fruits - Capsules, ascending, elliptic, 4-10 mm long, longitudinally ribbed.

Flowering - September - November.

Habitat - Dolomite glades, dry upland forest openings, fens, limestone glades.

Origin - Native to the U.S.

Lookalikes - Other species of Spiranthes, especially S. cernua.

Other info. - This small orchid is found in Missouri mostly in the south half of the state. It also occurs, in somewhat scattered fashion, thoughout most of the central U.S. Plants in the genus are easily identified as Spiranthes by their helical inflorescences of small white flowers. Identification to species can be more difficult. S. magnicamporum is characterized by robust inflorescences, which often appear doubly helical, and relatively large flowers with lateral sepals which are spreading and arching. The plant blooms late and is usually found on glades, or occasionally in lawns located in gladey regions with dolomitic substrate. In either case it can be fairly prolific. The flowers emit a sweetish fragrance of coumarin, which some people liken to vanilla.

Steyermark did not distinguish this species from S. cernua. Morphological differences between the two are subtle. The colloquial term "ladies' tresses" refers to a fancied resemblance of the inflorescence to a woman's braided hair. The epithet magnicamporum apparently means "of large plains."

Photographs taken at Victoria Glade, Jefferson County, MO, 10-7-2020 (SRTurner).