Platanthera grandiflora
Platanthera convallariifolia
greater purple fringe bog-orchid, greater purple fringe 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–several, ascending to rather wide spreading, scattered along stem or commonly loosely clustered on distal portion, gradually reduced to bracts distally;
blade elliptic-lanceolate to elliptic-oblong, 4.5–12 × 0.7–2.5 cm.
lax to rather dense.
moderately dense.
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, not showy, sometimes conspicuous, whitish green, perhaps more yellowish on lip;
lateral sepals spreading;
petals ovate-falcate, margins entire;
lip descending, linear to lance-linear, without basal thickening, 4–9 × 1–2 mm, margins entire;
spur slenderly to markedly clavate, rarely more slender, 4–8 mm, apex obtuse;
rostellum lobes widely divergent, directed downward, slightly angular, very small, obscure;
pollinaria straight;
pollinia remaining enclosed in anther sacs but apparently often fragmenting;
viscidia oblong to oblong-spatulate or elliptic-suborbiculate;
ovary slender to stout, mostly 6–10 mm.
= 42.
Platanthera grandiflora
Platanthera convallariifolia
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 convallariifolia is commonly reported from the Aleutians and adjacent coastal Alaska based on short, very broad-leaved plants with rather large flowers in dense, thick inflorescences. Those plants, however, apparently represent robust, maritime phenotypes of P. huronensis or in some cases P. stricta or P. dilatata comparable to those seen in Piperia elegans and Spiranthes romanzoffiana. In fact, typical Asiatic Platanthera convallariifolia is a slender-leaved plant entirely comparable in habit to P. huronensis. The two species are very similar, and they share a tetraploid chromosome number. Typical Asiatic P. convallariifolia is characterized by a linear lip and clavate spur about 2/3 to nearly the length of the lip. The lip occasionally varies to slightly lanceolate and the spur to somewhat saccate. The column appears somewhat broader than in P. huronensis, and viscidia also are apparently rather broad. A few specimens from the Aleutians and Alaskan peninsula exhibit these floral characteristics. Vegetatively, however, some Alaskan material is distinctive in the position and orientation of the leaves. In floral and vegetative characters, Alaskan plants furthermore intergrade with P. huronensis. Whether Alaskan plants are truly referable to P. convallariifolia is uncertain, and the status of the Asiatic species also needs study. Both P. convallariifolia and the Alaskan plants here referred to it appear to combine features of P. huronensis and P. stricta. Platanthera convallariifolia may have arisen through hybridization of these two species, or of P. stricta and P. dilatata, thus accounting for the difficulty in identification. The description presented here is based on few Alaskan plants and is apt to be too restrictive; therefore the poor understanding of the plant makes the present delimitation and distinctions from P. huronensis rather arbitrary.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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