Triphora trianthophora (Swartz) Ryd.
Nodding pogonia, three-birds
The genus Triphora contains about a dozen species confined to North
and Central America. Only one species is found in Wisconsin. The generic
name is derived from the Greek meaning "three-bearing," in reference
to the three flowers typically borne on each plant. The specific epithet
trianthophora is the Greek meaning "three-flower-bearing,"
again in reference to the three flowers typically borne on each plant.
DESCRIPTION: Plant glabrous,
8-20 cm tall, arising from a caudex of fleshy roots; roots typically spherical
tubers at their terminus, from which new plants arise. Stem typically pinkish
or purplish and appearing angular. Leaves 1-5 (typically 3-5 in flowering
individuals), orbicular, 5-10 mm long and 5-9 mm wide. Flowers 2-4,
located in the axils of the upper leaves. Sepals oblanceolate to
elliptic, 1-1.5 cm long and about 4 mm wide, pink to pinkish white, rarely
white; lateral sepals falcate. Petals similar to lateral sepals.
Labellum tripartite, pandurate in overall appearance, 6-10 mm long
and 3-8 mm wide, pink to whitish-pink and with 3 prominent rows of green
crenulate, fleshy ridges in the central portion.
SIMILAR SPECIES: I know of no other plant in the Wisconsin flora that
could be confused with Triphora.
HABITAT: Typically found in moist, rich deciduous forests. Most Wisconsin
collections come from under Acer saccharum or rarely Populus grandidentata.
In late summer, when Triphora is in flower, the understory of its
typical habitat is dark and devoid of competing vegetation. Of course, this
does not make it any easier to locate this reclusive rarity.
FLOWERING DATES: August 20-September 20.
POLLINATION: Observations by Williams
(1994) indicate that bumblebees probably serve as pollinators. Triphora
has a unique flowering phenology: typically the whole population flowers
synchronously, and flowers last only one day. According to Keenan
(1992), this synchronicity apparently extends over great areas, as during
1990 he and others observed Triphora flowering on the exact same
day in New Hampshire, Maine and Massachusetts. Most likely the synchrony
is maintained by large scale weather patterns or daylength cues. Triphora
flowers offer no nectar reward and are fairly rare; given this, the synchrony
and brief duration of flowering probably evolved as a means of ensuring
pollination by bumblebees, which quickly learn to avoid non-rewarding flowers.
DISCUSSION: Triphora trianthophora is extremely rare in Wisconsin,
where it is at the far northwestern corner of its range. Any populations
discovered should be left undisturbed and their location should be reported
to the Wisconsin DNR.
WI DISTRIBUTION: U.S. DISTRIBUTION:
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