Listera

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

Listera auriculata, Listera australis, Listera borealis, Listera caurina, Listera convallarioides, Listera cordata, Listera ovata, Listera smallii

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