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greater roundleaf orchid, large round-leaf orchid, large-leaf bog-orchid

eastern prairie fringe orchid, eastern prairie white fringe bog-orchid, prairie white fringe orchid

Habit Plants 23–63 cm. Plants 32–112 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.

several to many, ascending, scattered along stem, imperceptibly reduced to bracts distally;

blade lanceolate to ovate-lanceolate, usually to 20 × 4 cm.

Spikes

lax.

lax to 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, showy, corolla white, calyx green to whitish green;

lateral sepals porrect;

petals obovate to rarely flabellate, apically lacerate;

lip descending to horizontally projecting, deeply 3-lobed, without basal thickening, 14–22 × 15–29 mm, distal margins of lobes deeply incised, fringed, lateral lobes flabellate, usually broad, overlapping middle lobe, middle lobe flabellate, sometimes very broadly, emarginate;

spur slenderly clavate, 28–47 mm;

rostellum lobes nearly parallel, directed downward, short, rounded;

pollinaria geniculate;

pollinia directed forward (column appearing hooded), remaining enclosed in anther sacs;

viscidia orbiculate;

ovary slender, mostly 15–30 mm.

2n

= 42.

Platanthera macrophylla

Platanthera leucophaea

Phenology Flowering Jun–Aug. Flowering Jun–Aug.
Habitat Mesic to wet coniferous and deciduous forest Mesic to wet prairies, marshes, fens, lake shores, old fields
Elevation mostly 0–1000 m (mostly 0–3300 ft) 80–300 m (300–1000 ft)
Distribution
from FNA
CT; MA; ME; MI; MN; NH; NY; PA; VT; NB; NL; NS; ON; PE; QC
[WildflowerSearch map]
[BONAP county map]
from FNA
IA; IL; IN; LA; ME; MI; MO; NE; NJ; NY; OH; OK; VA; WI; ON
[WildflowerSearch map]
[BONAP county map]
Discussion

Of conservation concern.

A very rare hybrid with Platanthera psycodes, known only from Ontario, is P. ×reznicekii Catling, Brownell & G. Allen.

See the discussion under 22. Plantanthera praeclara.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 26. FNA vol. 26, p. 566.
Parent taxa Orchidaceae > subfam. Orchidoideae > tribe Orchideae > subtribe Orchidinae > Platanthera Orchidaceae > subfam. Orchidoideae > tribe Orchideae > subtribe Orchidinae > Platanthera
Sibling taxa
P. aquilonis, P. blephariglottis, P. brevifolia, P. chapmanii, P. chorisiana, P. ciliaris, P. clavellata, P. convallariifolia, P. cristata, P. dilatata, P. flava, P. grandiflora, P. hookeri, P. huronensis, P. hyperborea, P. integra, P. integrilabia, P. lacera, P. leucophaea, P. limosa, P. nivea, P. obtusata, P. orbiculata, P. peramoena, P. praeclara, P. psycodes, P. purpurascens, P. sparsiflora, P. stricta, P. tipuloides, P. zothecina
P. aquilonis, P. blephariglottis, P. brevifolia, P. chapmanii, P. chorisiana, P. ciliaris, P. clavellata, P. convallariifolia, P. cristata, P. dilatata, P. flava, P. grandiflora, P. hookeri, P. huronensis, P. hyperborea, P. integra, P. integrilabia, P. lacera, P. limosa, P. macrophylla, P. nivea, P. obtusata, P. orbiculata, P. peramoena, P. praeclara, P. psycodes, P. purpurascens, P. sparsiflora, P. stricta, P. tipuloides, P. zothecina
Synonyms Habenaria macrophylla, P. orbiculata var. macrophylla Orchis leucophaea, Habenaria leucophaea
Name authority (Goldie) P. M. Brown: Wild Fl. Notes 3: 23. (1988) (Nuttall) Lindley: Gen. Sp. Orchid. Pl., 294. (1835)
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