Hooded Ladies' Tresses (Bruce Peninsula Orchids)

Hooded Ladies' Tresses

Spiranthes romanzoffiana

Description ⁴

This beautiful orchid has white flowers that climb up the stem in three closely woven spirals. The leaves are clustered around the base of the stem and resemble those of grass. The group of orchids known as 'lady's tresses' are believed to have been so-named from the resemblance of the spiral florets to locks of braided hair.

Description ⁵

Plants 8–55 cm. Roots few–several, spreading to descending, tuberous, mostly to 1 cm diam. Leaves persisting through anthesis or fugaceous, basal, often on proximal portion of stem, ascending to spreading, linear to linear-lanceolate, elliptic, or oblanceolate, to 26 × 3 cm. Spikes usually very tightly spiraled, 3 flowers per cycle of spiral, rarely loosely spiraled or with more than 5 flowers per cycle; rachis glabrous to very sparsely pubescent, capitate glands short-stalked or often sessile (longest trichomes 0.03–0.18 mm). Flowers ascending, white to ivory, rarely yellowish white, tubular; sepals and petals connivent, forming hood above abruptly reflexed lip; sepals connate at base, 5.3–12.5 mm; petals linear to ovate, apex obtuse to subacute; lip pandurate, 4.8–10.2 × 1.6–6.8 mm, base broadly expanded, apex broadly dilated, separated by narrow isthmus, apical dilation variable, rarely lip nearly ovate, glabrous or with a few scattered trichomes on adaxial surface; veins typically 3, branches wide-spreading; viscidia linear-lanceolate; ovary 2–7 mm. Seeds monoembryonic. 2n = 44, 66, 88.

Biology ⁶

This orchid produces its beautiful flowers in July and August. Despite the fact that the plant flowers regularly, no cross-pollination has ever been confirmed in this country and no seed has yet been recorded. It is still not clear how Irish lady's tresses reproduces in the UK and Ireland, although recent genetic research has suggested that the northern populations of Scotland have reproduced sexually in the recent past. The plant also seems to reproduce vegetatively, although again it is not clear how.

Sources and Credits

(c) Dan and Raymond, some rights reserved (CC BY-NC-SA), http://www.flickr.com/photos/11158528@N08/1056412012
(c) Mike Patterson, some rights reserved (CC BY-NC), https://www.flickr.com/photos/mbalame/7639908504/
(c) Diana-Terry Hibbitts, some rights reserved (CC BY-NC), uploaded by Diana-Terry Hibbitts
(c) Wildscreen, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/6690948
(c) Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/5019469
(c) Wildscreen, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/6690951