Platanthera macrophylla |
Platanthera convallariifolia |
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greater roundleaf orchid, large round-leaf orchid, large-leaf bog-orchid |
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Habit | Plants 23–63 cm. | Plants 15–27 cm. |
Leaves | 2, in subequal basal pair lying on ground; bracts (very rarely, 0–)1–6, scattered along stem; blade broadly elliptic, orbiculate, or oblate, 7–24 × 5–19 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. |
Spikes | lax. |
moderately dense. |
Flowers | resupinate, rather showy; calyx mostly greenish white; corolla mostly white; lateral sepals reflexed to somewhat spreading; petals lanceolate-falcate, margins entire; lip descending to somewhat reflexed, linear-oblong to linear-lanceolate, without basal thickening, 10–23 × 1–2.5 mm, margins entire; spur slenderly clavate, 28–46 mm; rostellum lobes directed strongly forward, wide-spreading, angular; pollinaria nearly straight, (4.6–)4.7–6.8 mm; pollinia remaining enclosed in anther sacs; viscidia orbiculate; ovary slender to rather stout, mostly 16–29 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. |
Platanthera macrophylla |
Platanthera convallariifolia |
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Phenology | Flowering Jun–Aug. | Flowering late Jun–early Aug. |
Habitat | Mesic to wet coniferous and deciduous forest | Wet meadows, tundra, marshes, fens, stream banks, shores, seeping slopes |
Elevation | mostly 0–1000 m (mostly 0–3300 ft) | 0–400 m (0–1300 ft) |
Distribution |
CT; MA; ME; MI; MN; NH; NY; PA; VT; NB; NL; NS; ON; PE; QC
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AK; Asia (Kamchatka to Hokkaido) |
Discussion | 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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Source | FNA vol. 26. | FNA vol. 26, p. 559. |
Parent taxa | Orchidaceae > subfam. Orchidoideae > tribe Orchideae > subtribe Orchidinae > Platanthera | Orchidaceae > subfam. Orchidoideae > tribe Orchideae > subtribe Orchidinae > Platanthera |
Sibling taxa | ||
Synonyms | Habenaria macrophylla, P. orbiculata var. macrophylla | Limnorchis convallariifolius |
Name authority | (Goldie) P. M. Brown: Wild Fl. Notes 3: 23. (1988) | Fischer ex Lindley: Gen. Sp. Orchid. Pl., 287. (1835) |
Web links |