Listera auriculata |
Listera smallii |
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auricled twayblade |
Appalachian twayblade, kidney-leaf twayblade |
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Habit | Plants 5–25 cm. | Plants 5–35 cm. | ||||||||
Stems | pale green, succulent, glabrous. |
slender, succulent, glabrous. |
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Leaves | blade pale green, suborbiculate to suborbiculate-ovate or elliptic-ovate, 2.5–6 × 1.5–4.2 cm, apex subobtuse. |
blade dark green, ovate-reniform, 2–4 × 1.5–3.5 cm, apex acute, mucronate, or apiculate to short-acuminate. |
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Inflorescences | 5–20-flowered, lax, 20–100 mm; floral bracts broadly elliptic to oblong-lanceolate, 2–7 × 1–2 mm, apex obtuse; peduncle and rachis densely glandular-puberulent; bracts, pedicel, and ovary glabrous to rarely glabrate. |
5–15-flowered, lax, 40–100 mm; floral bracts ovate, 3–4 × 1.5 mm, apex acute; peduncle and rachis glandular-pubescent. |
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Flowers | pale green to blue-green, fading whitish with age; pedicels stout, 2.5–5 mm, glabrous, rarely glabrate; sepals and petals reflexed away from column and lip; dorsal sepal elliptic-obovate, 3–3.5 × 1.5–2 mm, apex subobtuse; lateral sepals elliptic, oblong, or ovate-lanceolate, strongly falcate, 3–4 × 1–1.5 mm, apex subobtuse to acute; petals linear-oblong to linear, falcate, 3–3.7 × 0.8 mm, apex obtuse; lip obovate to oblong, base of lip with auricles curving around and clasping base of column, apex slightly expanded, cleft approximately 1/5–1/3 its length, forming 2 broadly rounded lobes, margins ciliate; disc 3-veined with lateral veins branched, base with ridge in center; column arcuate, 2.5–3.3 × 1 mm, dilated at distal end. |
green, purple-brown, to pinkish tan; pedicel slender, 6–7 mm, glabrous; sepals strongly reflexed; dorsal sepal lanceolate to linear-lanceolate, 3–4 × 1 mm, apex acute; lateral sepals lanceolate to linear-lanceolate, 3–4 × 1 mm, apex acute; petals slightly reflexed, linear to linear-lanceolate, margins slightly revolute, apex acute; lip sessile, broadly obovate to cuneate, 6–10 × 5–7 mm, base with rounded lobule on each side, apex dilated and deeply cleft into pair of ± divergent broadly rounded lobes, shallowly toothed in sinus; column slightly arcuate, short, 1.5–3 × 1–2 mm. |
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Capsules | horizontal to semi-erect, ellipsoid, 8 × 4 mm. |
semierect, ellipsoid, 5 × 3 mm. |
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2n | = 38. |
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Listera auriculata |
Listera smallii |
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Phenology | Flowering late Jun–Aug. | Flowering Jun–Jul. | ||||||||
Habitat | Alluvial soils in low, moist, hardwood forests or mixed hardwood-coniferous forests, shrub swamps, sphagnum bogs, requires soil that remains cool throughout summer, with high degree of acidity | Damp humus in shady forests of Appalachian Mountains, often beneath Rhododendron in acidic soil, also in sphagnous thickets and bogs | ||||||||
Elevation | 0–1000 m (0–3300 ft) | 600–1300 m (2000–4300 ft) | ||||||||
Distribution |
ME; MI; MN; NH; NY; VT; WI; MB; NB; NL; NS; ON; PE; QC
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GA; KY; MD; NC; NJ; PA; SC; TN; VA; WV
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Discussion | Leaves of Listera auriculata forma trifolia (Lepage) Lepage are three in a whorl. Listera auriculata crosses with L. convallarioides to produce a natural hybrid L. ×veltmanii Case, originally discovered by H. S. Veltman and F. W. Case in 1962. The hybrid is almost exactly intermediate between its putative parents, and it is usually associated with one or the other parent (P. M. Catling 1976). Occasionally it appears to backcross with the parent species. Plants of the hybrid, although intermediate between the two putative parents, frequently differ from the parents in being much taller (to 2.5 dm). Also, the glandular pubescence of the pedicels and ovaries of the hybrid is shorter and sparser than that of the rachis; in L. convallarioides the glandular pubescence is as dense and long on pedicels as on the rachis, continuing on the ribs of the ovary. Pedicels and ovaries of L. auriculata are glabrous. The hybrids may be distinguished by using the following key. Listera ×veltmanii flowers in July and August. Its habitat is intermediate between those typical of the parents and apparently is often disturbed; 500–800 m. It is known from New Brunswick, Newfoundland and Labrador, Quebec, Ontario, Michigan, and Wisconsin. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Listera nipponica Makino, a species similar to L. smallii, occurs in the mountains of Japan. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 26, p. 589. | FNA vol. 26, p. 591. | ||||||||
Parent taxa | Orchidaceae > subfam. Epidendroideae > tribe Neottieae > subtribe Limodorinae > Listera | Orchidaceae > subfam. Epidendroideae > tribe Neottieae > subtribe Limodorinae > Listera | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | Bifolium auriculatum, Neottia auriculata, Ophrys auriculata | L. reniformis, Bifolium smallii, Neottia smallii, Ophrys smallii | ||||||||
Name authority | Wiegand: Bull. Torrey Bot. Club 26: 166, plate 356, fig. 2. (1899) | Wiegand: Bull. Torrey Bot. Club 26: 169. (1899) | ||||||||
Web links |