Platanthera obtusata (Banks ex Pursh) Lindley
Blunt-leaf orchid
The specific epithet obtusata is the Latin meaning "blunted,"
in reference to the blunted leaf of this species.
Photo courtesy of Mark Larocque
DESCRIPTION: Plant glabrous, arising from a cluster of fleshy,
thickened roots, 5-25 cm tall (including inflorescence). Leaf 1,
basal, obovate to oblanceolate, obtuse, 4-15 cm long and 1-4.5 cm wide,
keeled. Inflorescence a lax raceme, 10-30 flowered; flowers green
to yellowish- or whitish-green, each flower subtended by a lance-linear,
acuminate bract. Lateral sepals lanceolate to elliptic, 3-5 mm long
and 2-3 mm wide, reflexed, colored as flowers; dorsal sepal broadly
ovate, 2-4.5 mm long and 2-4 mm wide, connivent with petals over the column,
colored as flowers. Petals lanceolate, 2.5-5 mm long and 1-2 mm wide,
connivent with dorsal sepal over the column. Labellum linear-lanceolate
and acute, 4-8 mm long and 0.5-2 mm wide, colored as flowers; base of labellum
with a two small auricles and an acute nectar spur projecting behind,
4-7.5 mm long.
SIMILAR SPECIES: Platanthera obtusata could perhaps be confused
with P. clavellata, as both species
are found in swampy or boggy areas and have only one leaf. The two are easily
separated by the shape of the labellum: the labellum is narrow-lanceolate
and acute in P. obtusata, but is oblong and tridentate in P.
clavellata.
Platanthera obtusata could also perhaps be confused with either of
the two species of Malaxis, which also
have one leaf and my occur in the same habitat. P. clavellata is
easily separated, however, by its elongate nectar-spur, which is absent
in Malaxis.
HABITAT: Platanthera obtusata is typically found in sphagnous,
swampy areas, usually under Thuja or Picea. In northern Wisconsin,
P. obtusata can be very common in such habitats.
FLOWERING DATES: June 15-September 1.
POLLINATION: Platanthera obtusata is pollinated by mosquitos
(Stoutamire 1968, Thien
& Utech 1970) and small pyralid moths (Voss
& Riefner 1983). The research by Thien and Utech was conducted while
Leonard Thien was at the University of Wisconsin.
WI DISTRIBUTION: 
U.S. DISTRIBUTION:
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