Orchidaceae: Platanthera dilatata

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Family Name

Orchidaceae

Common Name

White bog orchid

Description

Platanthera dilatata is a perennial herb growing 15-70 cm tall. The mostly alternate, lanceolate leaves are cauline, 3-20 cm long and up to 3 cm wide with a pointed tip. the inflorescence is a loose to densely packed raceme, 5-25 cm long with 10-50 flowers, subtended by lanceolate floral bracts 5-40 mm long. The white flowers have 2 broad petal-like sepals that flare laterally, 4-8 mm long. Two lateral petals and an upper sepal form a hood, 4–6 mm long. The lower lip is narrower than the side sepals and initially curves up, touching the tip of the hood, and then flowing downward forming a sac-like to slender spur. The fruit is an ellipsoid capsule 8–15 mm long and 3-4 mm wide. White bog orchid is fairly rare in SD. It blooms in July in swampy forests and wooded bogs in and around Lawrence County in the State.

Synonym: Habeneria dilatata

Additional Notes

White bog orchid is uncommon in the state and should not be collected. The seeds are dust-like and require years to germinate and grow before plants can set outside. Because orchid seeds lack an endosperm, they require either infection by a fungal hyphae or a nutritive agar for germination. Cultivation of this species can be accomplished by purchasing plants from reputable greenhouses.