Isotria medeoloides
STATUS: Threatened
DESCRIPTION AND REPRODUCTION: Small whorled pogonia is a perennial with
long, pubescent roots and a smooth, hollow stem 9.5 to 25 centimeters (cm)
tall terminating in a whorl of 5 or 6 light green, elliptical leaves that
are somewhat pointed and measure up to 8 by 4 cm. A flower, or occasionally
two flowers, is produced at the top of the stem. Small whorled pogonia's
nearest relative is I. verticillata,
which is similar looking but can be distinguished by its purplish stem
and by differences in the flower structure. I. verticillata
is much more common and widespread than the small-whorled pogonia.
When not in flower, young plants of Indian cucumber-root (Medeola virginiana)
also resemble small whorled pogonia. However, the hollow stout stem of
Isotria
will separate it from the genus Medeola, which has a solid, more
slender stem.
Flowering occurs from about mid-May to mid-June, with the flowers apparently
lasting only a few days to a week or so. Also, this plant doesn't necessarily
flower annually. Usually only one flower is produced per plant. If pollination
occurs, a capsule may be formed which can contain several thousand minute
seeds. No evidence of insect pollination has been observed. This plant
is believed to be self-pollinating by mechanical processes. The flower
lacks both nectar guides and fragrance. There is no evidence for asexual
reproduction. Individual plants may not flower every year; and extended
dormancy, although not scientifically documented, is purported to occur
under certain conditions.
RANGE AND POPULATION The 23 populations in the Southeast Region occur
in North Carolina (5 populations); South Carolina (4 populations); Georgia
(13 populations); and Tennessee (1 population). Most Southeastern populations
number less than 25 plants. South Carolina has one population of over 25
plants, and Georgia has two populations numbering about 100 plants.
In the Southeast, North Carolina has two protected sites, both of which
are viable; South Carolina has four protected sites, two of which are viable;
and Georgia has seven protected sites, four of which are viable.
HABITAT: In North Carolina, this species is typically found in montane oak-hickory or acidic cove forests. The understory structure and composition of occupied sites can be quite variable, ranging from dense rhododendron thickets to open/sparse shrub and sub-shrub strata. Herbaceous cover tends to be sparse, however at least two sites are characterized by fairly dense stands of New York fern (Thelypteris noveboracensis). Sites currently or historically known to support this species range from 2000 to 4000 feet in elevation. The species does not appear to exhibit strong affinities for a particular aspect, soil type, or underlying geologic substrate. Habitat manipulation experiments in New England indicate that the species responds favorably to canopy openings, and may therefore be light-limited, however this remains to be observed in the southern Blue Ridge portion of the species' range.
REASONS FOR CURRENT STATUS: The current status of small whorled pogonia
is attributed to loss of habitat and overutilization for scientific and
private collections. However, some populations observed for a number of
years have also declined for unknown reasons.
Species Distribution from known occurrences. Species may occur in similar habitats in other counties.Green counties indicate observed within 20 years. Yellow counties indicate an obscure data reference to the species in the county. Red counties indicate observed more than 20 years ago.
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