Platanthera flava (L.) Lindl. - Pale Green Orchid

Habenaria flava plant

Family - Orchidaceae

Stems - To +/-50cm tall, erect, herbaceous, simple, single or double from the base, glabrous, with vertical ridges formed by decurrent leaf and bract tissue, green.

Leaves - 2-5 per stem, sessile, sheathing, glabrous, entire, narrowly elliptic-lanceolate, acute at apex, the largest with blades to +/-12cm long, +/-2cm broad, dull green above, slightly more shiny below. The midrib deeply impressed adaxially, expressed abaxially.

Habenaria flava leaves

Inflorescence - Terminal spike to +/-10cm long (tall). Axis glabrous. Each flower subtended by a lanceolate bract. Bracts shorter or longer than the flowers (depending on the variety), green, glabrous, entire.

Habenaria flava inflorescence

Flowers - Sessile, green. Floral tube -1cm long, typically twisted, glabrous. Sepals 3, ovate to orbicular, glabrous, entire, to 4mm long, 3mm broad. The lateral two spreading. Petals yellow-green. The spur to 6mm long, slightly curved, glabrous. Lower lip blunt at the apex to very slightly emarginate, to +/-4mm long, 3mm broad, glabrous, with two small basal projections and a tubercle at the base adaxially. Lateral petals rounded to ovate or obovate, spreading, 3-4mm long and broad, glabrous. Column -2mm long and broad, facing forward. Pollinia 1.3mm long. Pollen white.

Habenaria flava flowersFlowers.

Flowering - May - September.

Habitat - Mesic bottoms, mesic prairies.

Origin - Native to U.S.

Other info. - This species can be found scattered throughout Missouri but is relatively uncommon. The plant is fairly easy to identify because of its green flowers, which are spurred and have an undivided lower lip.
P. flava is commonly divided into two varieties. Both these varieties occur in Missouri but may be hard to differentiate. The varieties are differentiated on the basis of bract length on the inflorescence and also number of leaves per plant. The longer-bracted plants, var. herbiola (R. Br.) Luer are more common in Missouri than the shorter-bracted plants, var. flava.
A synonym for this species is Habenaria flava (L.) R. Br.

Photographs taken at Taberville Prairie, MO., 6-7-03.


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