Listera in Flora of North America @ efloras.org

33. Listera R. Brown, Hortus Kew. 5: 201. 1813.

[For Martin Lister (1638–1711), noted English physician and naturalist]

Lawrence K. Magrath & Ronald A. Coleman

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.

Species 25 (8 in the flora): cool temperate regions, Northern and Southern hemispheres.

1 Lip cleft 1/2–2/3 its length into 2 pointed, linear-lanceolate apical lobes; column 0.5–1 mm. (2)

+ 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 (1) Lip with basal auricles rounded and projecting distally, partially surrounding column; flowers smaller, dorsal and lateral sepals 1.5 mm. 1 Listera australis

+ 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. 2 Listera cordata

3 (1) Lip ± as broad at apex as at base, with basal auricles or lobes extending beyond column. (4)

+ Lip broader at apex than at base, without basal auricles or lobes extending beyond column. (5)

4 (3) Auricles curving around and clasping base of column; pedicels glabrous, rarely glabrate; dorsal sepal 3–3.5 mm, lateral sepals 3–4 mm. 3 Listera auriculata

+ Auricles divergent from column; pedicels glandular-pubescent; dorsal sepal 4–6 mm, lateral sepals 4.5–7 mm. 4 Listera borealis

5 (3) Lip with short claw, not sessile. 5 Listera convallarioides

+ Lip sessile, without claw. (6)

6 (5) Lip deflexed, base of lip without teeth or lobules; pedicels stout, 3–4 mm; capsules 10 mm. 6 Listera ovata

+ Lip not deflexed, base of lip with teeth or lobules; pedicels slender, 4–12 mm; capsules 5 mm. (7)

7 (6) Lip rounded or retuse at apex, base with 2 small, pointed auricles; pedicels glandular-puberulent. 7 Listera caurina

+ Lip deeply notched at apex into 2 broadly rounded lobes, base with rounded lobules on each side; pedicels glabrous. 8 Listera smallii

Lower Taxa