Coeloglossum is a monotypic genus of the family Orchidaceae, containing only Coeloglossum viride (Dactylorhiza viridis), known as the frog orchid or long-bracted green orchid. Coeloglossum viride has a circumboreal distribution covering much of the Palearctic ecozone, and throughout the mid to northern United States through Canada in the Nearctic ecozone. It is typically found growing in moist, rich soil in wet meadows, moist or wet deciduous woods and thickets, and is frequently found on steep slopes.
Plant arises from fleshy, forked roots and ranges in height from 10–55 cm. The leaves of C. viride are 5–14 cm long and 2–7 cm wide; leaves at the base of the orchid are obovate to elliptical, while leaves higher on the stem become lanceolate. Two to six leaves are found one one plant, and leafing is alternate.
Inflorescence of the orchid is a dense raceme (spike-like cluster) containing 7 to 70 small flowers. Flowers are greenish in color, and often tinged with purple, reddish, or red-brown color. Flowers are subtended by conspicuous long, tapering bracts which are 1–6 cm long, with the lower bracts longer and typically greatly exceeding the length of the flower. Sepals are oval with little or no point, 3–7 mm long and 2–4 mm wide and dark green. Sepals join with petals to form a hood opposite the lower petal of the flower. Petals are long and narrow, 3.5–5 mm long and about 0.5 mm wide, and curve inwards. The lower petal is strap-shaped and usually split at the very tip to form two or three tooth-like divisions, with the middle tooth smaller than the others. It is 5–11 mm long and 1–4 mm wide. A 2–3 mm long nectar spur projects behind the labellum.
Coeloglossum viride can be mistaken for Platanthera flava (the pale green orchid), but can be best distinguished by the labellum, which is notched at the apex and does not have the tubercle of P. flava.
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- Media related to Dactylorhiza viridis at Wikimedia Commons
- Data related to Dactylorhiza viridis at Wikispecies
- Coeloglossum at the Encyclopedia of Life
- Den virtuella floran - Distribution
- Acta Plantarum