The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

blunt-leaf bog-orchid, blunt-leaf rein-orchid, blunt-leafed rein orchid, bluntleaf orchid, northern small bog orchid, one-leaf rein-orchid, small northern 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 5.5–35 cm. Plants 11–130 cm or more.
Leaves

1(–2, rarely), spreading-ascending on base of stem;

bracts 0(–1, rarely);

blade linear-oblanceolate, elliptic, or broadly obovate, 3.5–15 × 0.8–5 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, not showy, greenish white to yellowish green;

corolla commonly whiter than calyx;

lateral sepals reflexed;

petals rhombic, lanceolate-falcate, margins entire;

lip descending, linear, narrowly lance-rhombic, or linear-hastate, with median basal thickening, unlobed, 2.5–8(–10) × less than 1–2 mm, margins entire;

spur slenderly conic, 3–8(–10) mm;

rostellum lobes directed forward, wide-spreading, rounded-angular;

pollinaria straight;

pollinia remaining enclosed in anther sacs;

viscidia orbiculate;

ovary rather slender to stout, mostly 3–10 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, 63 (American, as Habenaria obtusata), 126 (Eurasian, as Habenaria obtusata).

= 42.

Platanthera obtusata

Platanthera dilatata

Phenology Flowering Jun–Aug.
Habitat Mesic to wet coniferous forest, forested fens, sphagnum bogs, stream banks, tundra, moist roadsides
Elevation 0–3500 m (0–11500 ft)
Distribution
from FNA
AK; CO; ID; MA; ME; MI; MN; MT; NH; NY; OR; UT; VT; WA; WI; WY; AB; BC; MB; NB; NL; NS; NT; NU; ON; PE; QC; SK; YT; Eurasia [Platanthera obtusata subsp oligantha]
[WildflowerSearch map]
[BONAP county map]
from USDA
North America
[WildflowerSearch map]
Discussion

The rare Eurasian Platanthera obtusata subsp. oligantha (Turczaninow) Hultén differs from the North American subsp. obtusata in its smaller dimensions and rhombic-lanceolate lip. It is also said to be densely few-flowered, although some Siberian material is comparable to American plants. Supposedly intermediate plants are reported from Alaska, and much material from that area is reduced in stature and with smaller flowers than typical of American plants. In most cases, however, lips are relatively slender, and the plants seem merely to be stunted by their environment. One or two collections from the Alaskan Peninsula and Aleutians, however, seem entirely referable to subsp. oligantha with dense, few-flowered inflorescences of very small flowers with rhombic-lanceolate lips and shorter curved spurs. Eurasian plants are reported to be hexaploid or perhaps sometimes triploid, and if the apparent ploidy differences delimit the taxa, then it should be possible to unequivocally identify Alaskan plants.

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

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, p. 556. 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. macrophylla, P. nivea, 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 Orchis obtusata, Habenaria obtusata, Habenaria obtusata var. collectanea Orchis dilatata, Habenaria dilatata, Limnorchis dilatata
Name authority (Banks ex Pursh) Lindley: Gen. Sp. Orchid. Pl., 284. (1835) (Pursh) Lindley ex L. C. Beck: Bot. North. Middle States, 347. (1833)
Web links