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Platanthera
See list of 16 species in this genusPlatanthera ×vossii Case was reported from MA, ME by Kartesz (1999) based on personal communication with Paul Brown, but specimens are unknown. Brown (2002) resurrected the genus Gymnadeniopsis for species allied to Platanthera clavellata; however, phylogenetic studies to date (e.g., Hapeman and Inoue 1997) show that Gymnadeniopsis is nested within Platanthera and not monophyletic. Therefore, it is not recognized here. Reference: Sheviak (2002b).
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1a. Labellum simple, not divided into 3 portions, the margins entire, toothed, or fringed [Figs. 172,175]
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2a. Principal leaves all basal, the scapose stems without bracts or with 1–6 minute, bract-like leaves; pollen sacs divergent
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3a. Spur 3–8 (–10) mm long; scape with 0 (–1) bract-like leaves; basal leaves 0.8–5 cm wide, oblanceolate to obovate; ovary arcuate
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3b. Spur 11–46 mm long [Fig. 175]; scape with 0–6 bract-like leaves; basal leaves 4–22 cm wide, broad-elliptic or broad-obovate to orbicular; ovary straight
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4a. Scape with 0 (very rarely 1) bract-like leaves; ovary sessile; flowers green to green-yellow; labellum upcurved; spur tapering to apex
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4b. Scape with 1–6 bract-like leaves; ovary on a stipe 5–10 mm long; flowers white to green-white; labellum downward oriented; spur clavate-thickened at apex
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5a. Spur mostly 10–26 mm long; pollinaria 3–4.5 (–4.8) mm long; spur length plus twice the pollinarium length less than 38 (note: measurements in mm for calculation)
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5b. Spur 28–46 mm long; pollinaria (4.6–) 4.7–6.8 mm long; spur length plus twice the pollinarium length equal to or greater than 38
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2b. Principal leaves not confined to the base of the plant, the stems with 1–several leaves; pollen sacs mostly parallel
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6a. Margin of the labellum entire [Fig. 175]
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7a. Flowers white; labellum abruptly widened at the base; distance between anthers greater at apex than at base
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7b. Flowers green to white-green or yellow-green; labellum gradually widened at the base; distance between anthers greater at base than at apex
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8a. Labellum white-green, 5–12 mm long; anthers nearly parallel or slightly diverging basally, separated apically 0.6–1.5 mm; spur 4–12 mm long, cylindric to slender-clavate; pollinia remaining within anther sacs; flowers with a sweet, pungent scent
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8b. Labellum green to yellow-green, 2.5–6 mm long; anthers widely diverging basally, touching near apex or separated by a distance of no more than 0.3 mm; spur 2–5 mm long, clavate or, less commonly, cylindric; pollinia free of anther sacs and/or fragmenting and falling onto stigma (i.e., plants self-pollinating); flowers scentless
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6b. Margin of the labellum toothed, erose, or conspicuously fringed [Fig. 172]
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9a. Labellum conspicuously fringed, (4–) 8–19 mm long; spur (4–) 10–35 mm long
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10a. Flowers white; labellum short-fringed, with most or all marginal fringe segments shorter than width of medial, unfringed portion
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10b. Flowers orange to yellow-orange; labellum long-fringed, with marginal fringe segments equal to or longer than width of medial, unfringed portion
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11a. Labellum 8–19 mm long; spur 20–35 mm long; orifice of spur keyhole-shaped
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11b. Labellum 4–8 mm long; spur 4–10 mm long; orifice of spur triangular to keyhole-shaped
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9b. Labellum with basal or apical teeth or lobes, sometimes with crenations or irregular teeth, but definitely not fringed [Fig. 173], 3–7 mm long; spur 4–13 mm long
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12a. Labellum without a protuberance, with 3 teeth or very shallow lobes at the apex; stem with 1 principal leaf; spur 7–13 mm long
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12b. Labellum with a prominent, erect protuberance, usually with 2 basal teeth [Fig. 173], often crenate or irregularly toothed over the margin; stem with (1–) 2 or 3 (–4) principal leaves; spur 4–8 (–11) mm long
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1b. Labellum deeply 3-lobed, with erose or conspicuously fringed margins [Fig. 174]
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13a. Flowers green-white, yellow-white, or white (rarely tinged with bronze or rose); margin of the labellum conspicuously long-fringed, with some fringe segments exceeding ½ the length of the lobes of the labellum; labellum with cuneate to broad-cuneate lobes
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14a. Labellum green-white or yellow-white, 10–17 mm long, its segments cuneate; sepals 4.5–7 mm long, the lateral ones deflexed behind the labellum; spur 11–23 mm long; lateral petals entire (rarely slightly lacerate-toothed at apex); viscidia linear
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14b. Labellum white, 14–22 mm long, its lobes broad-cuneate; sepals 7–13 mm long, the lateral ones merely divergent with the tips curved forward; spur 28–47 mm long; lateral petals lacerate-toothed at apex; viscidia nearly orbicular
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13b. Flowers pink to rose-purple (very rarely white); margin of the labellum erose to short-fringed, with fringe segments up to ½ the length of the lobes of the labellum [Fig. 174]; labellum with broad-flabellate lobes
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15a. Orifice of spur horizontally rectangular or oblong; rostellum lobes short, rounded, nearly parallel, directed downward; labellum 5–13 mm long; spur 12–22 mm long
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15b. Orifice of spur circular [Fig. 174]; rostellum lobes angular, spreading, directed foward; labellum 10–25 mm long; spur 15–35 mm long
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Each photo represents one species in this genus.