Spiranthes ovalis Lindley var. erostellata Catling
Oval ladies'-tresses
The specific epithet ovalis is the Latin meaning "egg-shaped"
or "oval," and is apparently a reference to the shape of the inflorescence,
although Fernald (1950) felt that
it referred to the shape of the labellum. The varietal name erostellata
means, literally, "without a rostellum."
DESCRIPTION:
Plant finely pubescent above the leaves, 10-35 cm tall (including inflorescence),
arising from a cluster of fleshy, slender roots. Leaves 2-3(-5) mostly
basal, oblanceolate to linear-lanceolate, 6-12 cm long and 0.5-1.2 cm wide,
grading into reduced sheathing bracts below the inflorescence. Inflorescence
a thinly downy, spicate raceme of 20-40 small white flowers, 10-35 cm tall,
dense and multi-ranked and oval-shaped, each flower subtended by an elongate,
ovate-lanceolate bract. Sepals lanceolate-acuminate, 3-5 mm long
and about 2 mm wide, the lateral sepals with margins inrolled and tips recurved-spreading,
dorsal sepal connivent with petals to form a hood over the column and labellum,
sepals snowy white. Petals linear-lanceolate, 3-5 mm long and 1-2
mm wide, colored as the sepals and closely appressed to the sepals, tips
of sepals and petals reflexed slightly. Labellum ovate to rhombic-ovate,
3-4 mm long and 1-3 mm wide, white, the margins inrolled, the apex strongly
bent downwards, the base of the labellum with two small, pubescent calli.
SIMILAR SPECIES: Spiranthes ovalis is most likely to be confused
with S. cernua; however, the smaller size,
forested habitat, and unique inflorescence all easily separate the two.
S. ovalis could also possibly be confused with S.
lacera, but the unique green spot on the labellum of S.
lacera separates it from all the other species of Spiranthes
found in Wisconsin.
HABITAT: In Wisconsin, Spiranthes ovalis has only been collected
at one site. This site is a steeply sloped relict savannah, that had been
used for pasture. The canopy is Quercus macrocarpa and Carya ovata,
and the soil rocky and thin, with exposed limestone and chert.
FLOWERING DATES: The sole Wisconsin specimen was collected in near full
anthesis on September 20.
POLLINATION: This variety lacks a rostellum, and is thus self-pollinating
(Catling 1983c).
DISCUSSION: This autogamous variety was first described by Catling
(1983c). Sheviak (1974), and
later Homoya (1993), reported that
this variety has been spreading northward in the Midwest. Indeed, its recent
discovery (1991) in Wisconsin by Mark Leach may be taken as further evidence
of this spread (Mark and I are currently preparing a manuscript detailing
the discovery). However, since its discovery in Kalamazoo County, Michigan,
in 1966, it has failed to spread outside of that county. The plant is easily
overlooked, and flowers late (October), when few botanists are in the field.
Thus, the possibility remains that S. ovalis has not spread into
the state recently, but rather, has always been here, but has been rare
and overlooked.
WI DISTRIBUTION: 
U.S. DISTRIBUTION:
Go directly to Wisconsin herbarium records.
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