Listera
in W. Aiton and W. T. Aiton, Hortus Kew. 5: 201. 1813.
Herbs, perennial, terrestrial. Roots slender, fibrous. Stems slender to stout, glabrous proximal to leaves; cauline bracts 2(–3), enclosing base of stem. Leaves 2(–3, rarely), at apex of stem, opposite or subopposite, sessile, glabrous. Inflorescences terminal, 2–100-flowered racemes; peduncle and rachis densely glandular-pubescent or glabrate; floral bracts inconspicuous, lanceolate, elliptic, suborbiculate-ovate, rhombic-ovate, or oblong. Flowers resupinate, maroon-purple, yellowish green to dark green, blue-green, or pinkish tan; dorsal sepal ovate-elliptic, elliptic-obovate, linear-elliptic, or lanceolate; lateral sepals semiorbiculate-elliptic, ovate, linear-elliptic, or oblong-lanceolate, often falcate-recurved; petals reflexed, spreading, or connivent, linear, linear-oblong to lanceolate, or elliptic, falcate; lip prominently deflexed or not, sessile or clawed, linear-oblong to obovate, suborbiculate-ovate, or ovate-reniform, base of lip with or without prominent auricles or lobes, apex deeply 2-lobed, dilated to rounded, apiculate; calli various, papillose, pair of horns, or with 1–2 lamellae; column arcuate, thick, short, apex expanded or not; anther on adaxial side of column near apex; pollinia 2, yellow, soft; ovaries pedicellate. Fruits capsules, horizontal to semierect, ellipsoid, ovoid, or subglobose, glabrous or glabrate to glandular-pubescent.
Distribution
Cool temperate regions, Northern and Southern hemispheres.
Discussion
Species 25 (8 in the flora).
Selected References
None.
Lower Taxa
Key
| 1 | Lip cleft 1/2–2/3 its length into 2 pointed, linear-lanceolate apical lobes; column 0.5–1 mm. | > 2 |
| 1 | Lip expanded at apex or if cleft, then less than 1/2 its length and apical lobes rounded; column 1.5–4 mm. | > 3 |
| 2 | Lip with basal auricles rounded and projecting distally, partially surrounding column; flowers smaller, dorsal and lateral sepals 1.5 mm. | Listera australis |
| 2 | Lip with basal auricles or lobes pointed and projecting outward like horns, not partially surrounding column; flowers larger, dorsal and lateral sepals 2–3 mm. | Listera cordata |
| 3 | Lip ± as broad at apex as at base, with basal auricles or lobes extending beyond column. | > 4 |
| 3 | Lip broader at apex than at base, without basal auricles or lobes extending beyond column. | > 5 |
| 4 | Auricles curving around and clasping base of column; pedicels glabrous, rarely glabrate; dorsal sepal 3–3.5 mm, lateral sepals 3–4 mm. | Listera auriculata |
| 4 | Auricles divergent from column; pedicels glandular-pubescent; dorsal sepal 4–6 mm, lateral sepals 4.5–7 mm. | Listera borealis |
| 5 | Lip with short claw, not sessile. | Listera convallarioides |
| 5 | Lip sessile, without claw. | > 6 |
| 6 | Lip deflexed, base of lip without teeth or lobules; pedicels stout, 3–4 mm; capsules 10 mm. | Listera ovata |
| 6 | Lip not deflexed, base of lip with teeth or lobules; pedicels slender, 4–12 mm; capsules 5 mm. | > 7 |
| 7 | Lip rounded or retuse at apex, base with 2 small, pointed auricles; pedicels glandular-puberulent. | Listera caurina |
| 7 | Lip deeply notched at apex into 2 broadly rounded lobes, base with rounded lobules on each side; pedicels glabrous. | Listera smallii |