Amerorchis rotundifolia (Banks) Hulten
Small round-leaved orchis
The genus Amerorchis was created by Hulten in 1968 to house this
sole North American species, previously considered to a species of Orchis,
hence the generic name. The specific epithet rotundifolia is the
Latin meaning "round leaf," and refers to the rounded leaves of
Photo courtesy of Emmett Judziewicz
DESCRIPTION: Plant glabrous, 10-25 cm tall, arising from a caudex
of slender roots. Leaf solitary, basal, 5-10 cm long and 7-9 cm wide.
Inflorescence a loose raceme 11-23 cm tall, 5-15 flowered. Sepals
ovate-elliptic to ovate, 7-10 mm long and 5 mm wide, pink to pinkish white,
rarely white; dorsal sepal connivent with petals to form a hood over the
column. Petals 5-6 mm long and 2-3 mm wide, closely appressed to
the dorsal sepal and colored as the sepals. Labellum tripartite,
center lobe often bilobed at the terminus, 6-10 mm long and 3-8 mm wide,
whitish pink to white and spotted with deep magenta; labellum with a 5 mm
nectar spur projecting behind.
SIMILAR SPECIES: It is unlikely that this species could be confused
with any other in the Wisconsin flora.
HABITAT: In Wisconsin, Amerorchis is found almost exclusively
in White Cedar (Thuja occidentalis) and Larch (Larix laricina)
bogs--which tend to be calcareous, and apparently has a distinct preference
for calcareous substrate in other parts of its range.
FLOWERING DATES: June 5 to July 5.
POLLINATION: To the best of my knowledge, no records exist for pollination
of this species.
DISCUSSION: Fuller (1933) reports
that the soil around the roots of Amerorchis in Wisconsin was found
to be "minimalkaline." This species is extremely rare in Wisconsin,
probably because it is at the extreme southern part of its distribution
WI DISTRIBUTION: U.S. DISTRIBUTION:
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