Platanthera grandiflora
Platanthera limosa
greater purple fringe bog-orchid, greater purple fringe orchid
Thurber's bog orchid
2–6, wide-spreading and recurved to somewhat ascending, scattered along stem, gradually reduced to bracts distally;
blade lanceolate, elliptic, oblong-elliptic, or oblong-obovate, 13–24 × 2.5–9 cm.
few to several, spreading-ascending on base of stem, gradually reduced to bracts upwards;
blade lanceolate, 9–28 × 1.2–3.5 cm.
lax to rather dense.
dense to lax.
resupinate, showy, lavender- to rose-purple, rarely white;
lateral sepals spreading to somewhat reflexed;
petals ovate, oblong, elliptic-oblong, or oblong-obovate, margins crenate to dentate-lacerate, sometimes nearly entire;
lip descending to somewhat porrect, deeply 3-lobed, without basal thickening, 10–25 × 14–26 mm, distal margins of lobes fringed, usually deeply, lateral lobes sometimes perpendicular to middle lobe, lateral lobes cuneate, often broadly so, middle lobe broadly cuneate-flabellate, often emarginate to 2-fid;
spur clavate, 15–35 mm;
rostellum lobes directed forward, spreading, angular;
pollinaria nearly straight;
pollinia remaining enclosed in anther sacs;
viscidia orbiculate;
ovary slender to stout, 12–25 mm.
resupinate, inconspicuous, green;
lateral sepals reflexed to spreading;
petals lanceolate-, ovate-oblong-, or ovate-falcate, margins entire;
lip descending to reflexed, linear-oblong, linear-elliptic, or rhombic-ovate, usually with inconspicuous to scarcely discernable (possibly sometimes absent) median basal thickening, 2.5–8.5 × less than 1–3.5 mm, margins entire;
spur filiform, tapering toward apex, very rarely filiform-conic from slightly stout base, 8–25 mm;
rostellum lobes mostly parallel, closely spaced, directed downward, very small, rounded, obscure;
pollinaria straight;
pollinia remaining enclosed in anther sacs;
viscidia evidently elliptic-oblong;
ovary rather slender to stout, mostly 4.5–11 mm.
= 42.
Platanthera grandiflora
Platanthera limosa
Platanthera grandiflora is known to hybridize with P. lacera in the northeasternmost portion of its range, where the species bloom simultaneously. The name P. ×keenanii P. M. Brown has recently been proposed for these hybrids, but the complex synonymy of this group dictates that types be checked for possible priority. See the discussion under P. lacera. A few specimens also suggest very rare hybridization with P. psycodes (W. P. Stoutamire 1974).
Rare white-flowered plants may be separated from 23. Platanthera leucophaea by the orientation of the pollinia.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Platanthera limosa is traditionally distinguished from other slender-spurred plants and from P. sparsiflora by the presence on the lip of a median thickening that culminates in a small basal process. Although diagnostic when present, this feature is often obscure, especially in live material, and seems to be lacking in some plants. Platanthera limosa is most consistently separated from other green-flowered species by the combination of very small, narrow column and slender spur much longer than the lip. These features are in contrast to the very large, broad columns of P. sparsiflora and P. zothecina and much shorter spurs of the P. hyperborea complex. The lips of most plants are elliptic to elliptic-oblong, unlike any other species except the Aleutian P. tipuloides, and such plants are readily determined by lip shape and spur characters. Within populations plants may vary greatly in flower size, spur shape and length, and the ratio of spur to lip length. Individual plants may vary markedly in size of the flowers and density of the inflorescence in different years. That situation warrants additional study, as it may obscure the presence of other taxa.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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