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northern tubercled bog-orchid, palegreen orchid

large round-leaf orchid, large round-leaf rein orchid, lesser roundleaf orchid, round-leaf bog-orchid, round-leaf orchid

Habit Plants 13–65 cm. Plants 17–62 cm.
Leaves

(1–)2–3(–4), spreading to ascending, gradually to rather abruptly reduced to bracts distally;

blade lanceolate to elliptic-oblong, 5–35 × 1–7 cm.

2, in subequal basal pair lying on ground;

bracts (very rarely, 0–)1–6, scattered along stem;

blade broadly elliptic to orbiculate or oblate, 5–21 × 3–22 cm.

Spikes

lax to dense.

lax to dense.

Flowers

resupinate, inconspicuous, yellowish green;

lateral sepals porrect to reflexed;

petals oblong-orbiculate to ovate, apex somewhat crenulate;

lip descending to commonly reflexed, 2–6 × 1.8–5 mm, base auriculate, with prominent central tubercle, distal margin entire to slightly crenulate;

spur cylindric to strongly clavate, 4–8(–11) mm, apex rarely 2-lobed;

rostellum lobes mostly parallel to slightly diverging, directed downward, minute, obscure;

pollinia remaining enclosed in anther sacs;

viscidia mostly quadrangular, oblong-quadrangular, orbiculate, or broadly asymmetric, commonly canaliculate to nearly cylindric and difficult to assess;

ovary rather slender to stout, mostly 8–10 × 2 mm.

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, 7–17 × 1–2.5 mm, margins entire;

spur slenderly clavate, 14–27 mm;

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

pollinaria nearly straight, 3–4.5(–4.8, very rarely) mm;

pollinia remaining enclosed in anther sacs;

viscidia orbiculate;

ovary slender to rather stout, mostly 10–26 mm.

2n

= 42.

Platanthera flava

Platanthera orbiculata

Phenology Flowering Jun–Aug(–Sep).
Habitat Mesic to wet coniferous and deciduous forest, fen forest
Elevation 0–1500 m (0–4900 ft)
Distribution
from USDA
e North America
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; ID; IL; IN; MA; MD; ME; MI; MN; MT; NC; NH; NJ; NY; OH; OR; PA; SD; TN; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NF; NS; NT; ON; PE; QC; SK
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 2 (2 in the flora).

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

The key will permit determination of most specimens of Platanthera orbiculata and P. macrophylla. More precise discrimination of ambiguous specimens is possible by use of the formula from A. H. Reddoch and J. M. Reddoch (1993): spur length + (2 × pollinarium length), which for P. orbiculata is less than 38 and for P. macrophylla is equal to or greater than 38.

Considerable variation in size and shape of leaves occurs, and although to some extent regional in nature, intergradation is complete; recognition of infraspecific taxa is unwarranted. A few collections from isolated areas on the Pacific Coast of Canada are noteworthy, however. Those are small, few-flowered plants with rather narrow leaves borne alternately or suboppositely toward the base of the stem, as in some Asiatic species. They are in some respects very similar to Platanthera freynii Kränzlin, an Asiatic species distinguished primarily by its abruptly narrowed petals, in contrast to the generally broader, but variable, petals in North American plants. These western plants warrant further study to establish their identity and to elucidate relationships between North American and Asiatic species.

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

Key
1. Lip (excluding auricles) subquadrangular, suborbiculate, or broadly ovate, often emarginate; inflorescences usually rather lax, slender (this enhanced by floral bracts mostly shorter than flowers).
var. flava
1. Lip (excluding auricles) oblong, usually obtuse, (rarely triangular, acute); inflorescences usually rather dense, stout (this emphasized by floral bracts usually long, often greatly exceeding flowers).
var. herbiola
Source FNA vol. 26, p. 563. FNA vol. 26, p. 555.
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. 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
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. obtusata, P. peramoena, P. praeclara, P. psycodes, P. purpurascens, P. sparsiflora, P. stricta, P. tipuloides, P. zothecina
Subordinate taxa
P. flava var. flava, P. flava var. herbiola
Synonyms Orchis flava, Habenaria flava, Perularia scutellata Orchis orbiculata, Habenaria orbiculata, Habenaria orbiculata var. lehorsii, Habenaria orbiculata var. menziesii, P. orbiculata var. lehorsii
Name authority (Linnaeus) Lindley: Gen. Sp. Orchid. Pl., 293. (1835) (Pursh) Lindley: Gen. Sp. Orchid. Pl., 286. (1835)
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