Vascular Plants of North Carolina
Account for Southern Rein Orchid - Platanthera flava   (L.) Lindley
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Section 5 » Order Orchidales » Family Orchidaceae
Author(L.) Lindley
DistributionThis is the more eastern (Coastal Plain and Piedmont) form of the broad sense Platanthera flava (formerly Habenaria flava). It ranges over the western two-thirds of the Coastal Plain and much of the Piedmont, but it is spottily distributed over this large range. It seems to be absent from the eastern Coastal Plain (east of Northampton, Beaufort, Craven, and Carteret counties). [The recently split-off P. herbiola is limited to the mountains and foothills in NC, but the ranges might overlap, and the maps may need to be adjusted with more study of specimens.]

This species ranges from NJ and MO south to central FL and eastern TX; it is disjunct in Nova Scotia.
AbundanceRare to uncommon in counties close to the Fall Line in the northwestern Coastal Plain and northeastern Piedmont. Rare over most of the rest of the Piedmont (to Forsyth and Gaston counties), and also over most of the southern Coastal Plain. Where found, it can occur in dense stands of up to 50 or more plants.
HabitatThis is a Platanthera of wet shaded habitats, being most often found in floodplain pools and other wet ground in lowland hardwood forests and bottomlands. It grows in a few similar habitats to P. clavellata, though that species has a wider range of moist habitats and does not grow in as dense stands as can P. flava.
See also Habitat Account for General Broadleaf Herbaceous Mires
PhenologyIt can bloom any time from March to September (according to RAB), but is usually in bloom from about May to July. It fruits shortly after blooming.
IdentificationThis Platanthera looks quite a bit different from others in the genus in the Coastal Plain and Piedmont. It grows to 1-2 feet tall and has a few narrow and erect leaves coming off the lower part of the stem. The inflorescence is a narrow raceme (and almost looks like a spike) instead of a more open raceme. The several dozen flowers tend to match the stem color, being pale greenish or pale yellow-green, curved to face downward; each flower is barely 1/4-inch across and contains a leaf-like bract beneath it. At first glance, it does not look like an orchid, even when in bloom, and one must often be within a foot of it to see the orchid flower structure. The most obvious aspect of the species is its proclivity of growing in fairly dense stands, often one plant just a few inches from another, with a population often covering 5-10 feet in diameter with many plants. The very similar P. herbiola, from which it was recently split, has bracts noticeably longer than nearly all of the flowers, the flowers more densely packed along the flowering stem, and has a more green lip (as opposed to yellowish-green in P. flava). The ranges of these two might not quite overlap in NC, but in the western Piedmont it is possible that both could be found in the same county some day.
Taxonomic CommentsNearly all Platanthera species in NC were formerly placed in the genus Habenaria (i.e., as Habenaria flava). In recent decades, nearly all references have this species split out, but many consider them as varieties only -- P. flava var. flava and P. flava var. herbiola. This website follows Weakley (2018) and considers these as separate species.

Other Common Name(s)This is another Platanthera with no well-established common name. Other names include Northern Tubercled Bog Orchid (ugh!), Tubercled Orchid, Pale-green Orchid, and Rein Orchid.
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