Orchids
Spiranthes
1 Stem of inflorescence (rachis) with all hairs not glandular, tapering to a pointed tip; [flowers Mar-Sept] ...........Spring Ladies'-tresses1 Stem of inflorescence glabrous, or with some or all hairs gland-tipped, or otherwise blunt-ended.
2 Flower lip bright yellow or orange-yellow, with greenish veins; sepals and petals pure white; [flowers May-Jul]...................................
..........................................................................................................................................................................Wide-leaved Ladies'-tresses
2 Flower lip either white, or lip yellowish and lacking greenish veins; sepals and petals creamy, ivory, yellow, or greenish.
3 Lip with conspicuous, terminally widened, greenish (rarely yellowish) diverging veins extending nearly to the tip;
[flowering March-July]...............................................................................................................................Grass-leaved Ladies'-tresses
3 Lip lacking conspicuous, terminally widened, greenish diverging veins (veins not terminally widened).
4 Rachis glabrous; flowers gaping from near middle, the tubular portion less than 3mm long; lip pure white;
[flowering June-September] ............................................................................................................................... Little Ladies'-tresses
4 Rachis pubescent or glabrous; flowers gaping only from beyond the middle, the tubular portion more than 3mm long; lip white,
creamy, yellow, or centrally green.
5 Inflorescence with 3 or 4 flowers per cycle of spiral, the spiral usually tight and obscure, but then with 3 or 4 secondary ranks of
flowers evident; [collectively flowering August-December] ....................................................................................................... Key A
5 Inflorescence with 5 or more flowers per cycle of spiral, the spiral usually open and obvious; [collectively flowering
February-December] .................................................................................................................................................................... Key B
1 Flower lip only slightly or not at all differentiated from petals; buds often not opening; pollen column normal, or abnormal or aborted;
leaves usually absent at flowering ........................................................................................................................ Nodding Ladies'-tresses
1 Flower lip clearly differentiated from petals; buds opening into normal flowers; column normal; leaves present or absent at flowering.
2 Plants to about 50cm tall, not colonial; leaves comparatively slender, flaccid with thickened midrib, the petioles of the basal leaves less
than 6mm wide; leaves wholly basal or the lower sheaths with ascending-spreading blades; perianth usually 8-11mm long; lip
membranaceous to fleshy, less than 7mm long.................................................................................................. Nodding Ladies'-tresses
2 Plants to over 100cm tall, forming clonal colonies; leaves broad, stiffly thickened, the petioles of basal leaves 7mm or more wide;
leaves up the stem, with spreading recurved blades on the lower sheaths, frequently also on the upper, with leaves extending to the
inflorescence; petals 10-15mm long (sometimes less in weak plants); lip fleshy, usually over 7mm long.........Marsh Ladies'-tresses
1 Lip with lacerate-dentate tip; leaves usually linear, more than 30× as long as wide, persistent and present at flowering;
[flowering May-August] ..........................................................................................................................................Lacelip Ladies'-tresses
1 Lip with undulate to crisped tip; leaves broader, less than 30× as long as wide, either persistent and present at flowering, or withering
prior to flowering.
2 Flowers comparatively large and stout, the petals 5-10mm long, white to yellowish, the lip often darker centrally but not green or
greenish yellow; leaves ascending, relatively slender, present at flowering; rachis conspicuously and densely glandular-pubescent;
[flowering August-November] ........................................................................................................................... Nodding Ladies'-tresses
2 Flowers comparatively small and slender, the petals usually less than 5.5mm long; leaves strictly basal, spreading and ovate to obovate or
oblanceolate; rachis glabrous or densely but minutely glandular-pubescent; [flowering February-September]...........................
...............................................................................................................................................................Northern Slender Ladies'-tresses