Sphinx ladies’ tresses

not listed

N5? - Secure

SNR - Unranked

not listed

FACW - Facultative wetland

FACW - Facultative wetland

FACW - Facultative wetland

Sphinx ladies’ tresses is a 4″ to 16″ tall, erect, perennial forb that rises on a single stalk from a tight cluster of fleshy roots.

There are usually 2 or 3, sometimes 4 or 5, grass-like mostly basal leaves which may be withered or present when the plant is in bloom. They are light green, ascending to spreading, linear lance-shaped to linear inversely lance-shaped, 4″ to 8″ long, and 3 ⁄16″ to ⅜″ wide. They taper to a sharp point at the tip. The margins are untoothed.

The stems are erect, unbranched, and leafless except for 3 to 6 bracts below the inflorescence, The bracts are alternate, scale-like, sheathing, and hairless.

The inflorescence is 2 or 3 intertwined, tightly spiraling, 2″ to 5″ long flower spikes at the top of the stem with 20 to 60 individual flowers. The flowers on each spike are arranged in spirals of 3 or 4 flowers per cycle of spiral, rarely in loose spirals of 5 or more flowers per cycle. The spirals are not evident due to the intertwining of the spikes. The spikes are light green and moderately hairy.

Each flower is subtended by a scale-like, egg-shaped to lance-shaped bract.

The flowers are about ½″ long and abruptly nodding at the base. There are 3 white to cream colored or ivory petals and 3 similar petal-like sepals. The upper 2 petals converge with but do not fuse with the upper sepal to form a hood over the united filaments and style (column). The tips of the upper petals and sepal curve upward slightly. The lower petal forms an egg-shaped lip that arches strongly downward. The central portion of the lip is sometimes slightly yellowish and is constricted near the middle. The lip is crisped at the tip. The lateral 2 sepals are linear- lance-shaped, straight or slightly spreading, not recurving, often slightly ascending. The margins of the lateral sepals are rolled inward. The flowers are not scented.

4″ to 16″

White to cream colored or ivory

Great Plains ladies’ tresses (Spiranthes magnicamporum) stems are leafless at flowering. The lateral 2 sepals are shaped like a pair of cow’s horns. The central portion of the lower lip is never constricted. The flowers are almond-scented.

Moist. Prairies, bogs, fields, ditches. Full sun.

July to September

Sources

7, 24, 29, 30.

Native

Ancient hybridization between species in the Sprianthes genus has evolved genetically distinct but morphologically overlapping species. Spiranthes cernua has been long known to be a species complex with overlapping characteristics that make identification to the species in the field or in the lab difficult or impossible. A recent study (Pace and Cameron, 2017) clarified the species boundaries within the Spiranthes cernua species complex using molecular DNA sequences and morphological variation. The study resulted in the description of three new species, a new hybrid, and a much narrower concept of the species Spiranthes cernua. The Upper Midwestern ladies’ tresses formerly included in the species Spiranthes cernua are now assigned to the new species Spiranthes incurva.

Location: Sax-Zim Bog, St. Louis Co.