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

bog candles, bog-candle, boreal bog-orchid, fragrant white bog orchid, fragrant white rein orchid, rein orchid, scent-bottle, white bog orchid, white northern bog-orchid, white orchid, white rein-orchid

Habit Plants 23–63 cm. Plants 11–130 cm or more.
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 recurved-spreading, scattered along stem, gradually reduced to bracts distally;

blade linear, linear-lanceolate, oblong, or oblanceolate, 3.5–32 × 0.3–7 cm.

Spikes

lax.

very lax to very 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, rather showy, conspicuous, white;

lateral sepals spreading to reflexed;

petals ovate- to linear-lance-falcate, margins entire;

lip descending or apex adhering to dorsal sepal and petal apices, linear-lanceolate to lanceolate, without basal thickening, 4–11 × 2–5 mm, base slightly rounded-dilated to orbiculate, rarely rhombic, margins entire;

rostellum lobes parallel to slightly divergent, directed downward, very small, obscure, rounded;

pollinaria straight;

pollinia remaining enclosed in anther sacs;

ovary rather slender to stout, 5–15 mm.

2n

= 42.

Platanthera macrophylla

Platanthera dilatata

Phenology Flowering Jun–Aug.
Habitat Mesic to wet coniferous and deciduous forest
Elevation mostly 0–1000 m (mostly 0–3300 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 USDA
North America
[WildflowerSearch map]
Discussion

Varieties 3 (3 in the flora).

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

Key
1. Spur shorter than lip, clavate to slightly capitate.
var. albiflora
1. Spur nearly equaling to exceeding lip, slender to slightly clavate.
→ 2
2. Spur about equal to lip (mostly within 2 mm).
var. dilatata
2. Spur markedly exceeding lip (commonly 11/2 or more times length of lip).
var. leucostachys
Source FNA vol. 26. FNA vol. 26, p. 556.
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. flava, P. grandiflora, P. hookeri, P. huronensis, P. hyperborea, P. integra, P. integrilabia, P. lacera, P. leucophaea, 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
Subordinate taxa
P. dilatata var. albiflora, P. dilatata var. dilatata, P. dilatata var. leucostachys
Synonyms Habenaria macrophylla, P. orbiculata var. macrophylla Orchis dilatata, Habenaria dilatata, Limnorchis dilatata
Name authority (Goldie) P. M. Brown: Wild Fl. Notes 3: 23. (1988) (Pursh) Lindley ex L. C. Beck: Bot. North. Middle States, 347. (1833)
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