Ponthieva racemosa (Walter) C. Mohr (redirected from: Arethusa racemosa)
Family: Orchidaceae
[Arethusa racemosa Walter]
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Plants 30-60 cm. Roots 2-3 mm diam. Stems subterranean, short. Leaves green at anthesis, 2-6, subpetiolate; blade elliptic to oblanceolate, 5-17 × 2-5 cm, apex rounded to acute. Inflorescences: peduncle to 25 cm, partially enclosed by tubular sheaths, proximalmost sometimes leafy; rachis laxly 20-35-flowered, 5-25 cm; floral bracts narrowly lanceolate, clasping base of ovary, to 10 mm, apex acuminate, pubescent. Flowers: sepals greenish white, adaxially pubescent; dorsal sepal distinct, ovate-elliptic to elliptic-lanceolate, 4-7 × 2-3 mm, apex obtuse; lateral sepals broadly, obliquely ovate, 4.3-6.5 × 2.5-3.5 mm, apex acute to obtuse; petals white, green-veined, obliquely triangular, 4-6 × 3.5-5 mm, margins minutely ciliate or entire, glabrous; lip white with green, deeply concave center, distinctly clawed, suborbiculate, 5-7 × 5-7 mm, apex short-caudate; column white, 4-5 mm; pedicellate ovary 10-20 mm. Capsules 8-13 mm.

Flowering fall--winter (Sep--Feb). Moist, shady hammocks, swamps, ravines, wet savannas, pine forests; 0--50 m; Ala., Fla., Ga., La., Miss., N.C., S.C., Tex., Va.; Mexico; West Indies; Central America; South America.

In Florida, Ponthieva racemosa is self-compatible but not autogamous. Natural fruit-set in one population in northern Florida was 35% (J. D. Ackerman 1995). In Florida, small halictid bees were observed visiting the flowers (C. A. Luer 1972).

Lvs very thin, spreading on the ground, elliptic, 5-10 cm, acute, tapering to the base; scape 2-4 dm, glandular-hairy, as also the axis and pedicels; sep white with green stripes, 5-6 mm, ovate to oblong; lateral pet white with greenish-yellow veins, broadly falcate-ovate, 5 mm, nearly as wide; lip arising near the middle of the column, rotund, white, veined with green, 6 mm, abruptly pointed. Bogs and wet woods on the coastal plain; se. Va. to Fla. and trop. Amer. Sept., Oct.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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