Sep and lateral pet similar, the pet connivent with the upper sep (or with all the sep) and projecting forward over the lip and column; lip oblong or ovate to pandurate in outline, bearing 2 small callosities near the basal angles, its margins below the middle upturned and embracing the short column, the more distal part ±decurved, not crested or ridged, but often with a median area of different color; anther borne on the back of the column, its 4 pollinia attached to the viscidium and commonly surpassed by the bidentate or bifid rostellar beak; slender herbs with narrow (seldom broader), chiefly basal lvs, the erect stem bearing several reduced lvs (or mere sheaths) and a terminal, spirally twisted, spike-like raceme; fls mostly white or whitish at least in large part. (Ibidium) 300, cosmop.
The fls decrease in size progressively from the bottom to the top of the infl. Measurements given here are for fls in the lower third. In spp. 1-5 the infl is ordinarily such a close spiral that the fls appear to be in 3 or 4 vertical, straight or somewhat spiral ranks.
In spp. 6-11 the infl is typically more lax and open, with the fls obviously in a single long spiral, but some of these spp. vary to forms with the infl approaching that of the first group. A number of hybrids have been documented.
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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