13.10   TORREYOCHLOA G.L. Church

PRELIMINARY DRAFT TREATMENT. Please send comments to Mary Barkworth.
Jerrold I. Davis

Plants perennial; rhizomatous. Culms 18-145 cm, erect to decumbent, often rooting at the nodes; internodes hollow. Sheaths open to the base; auricles absent; ligules membranous; blades flat. Inflorescences terminal panicles; branches scabrous, usually densely scabrid distally. Spikelets pedicellate, laterally compressed to terete; florets 2-8; disarticulation above the glumes and between the florets. Glumes unequal, shorter than the lowest lemma, rounded to weakly keeled, veins obscure to prominent, unawned; lower glumes 1(3)-veined; upper glumes (1)3(5)-veined; calluses blunt, glabrous; lemmas rounded to weakly keeled, sometimes pubescent, particularly below, prominently (5)7-9-veined, veins more or less parallel, veins and interveins usually scabridulous, particularly distally, lateral veins usually reduced or absent, apices scabridulous and entire to serrate-erose, unawned; paleassubequal to the lemmas, 2-veined; lodicules 2, free, glabrous, entire or toothed; anthers usually 3; ovaries usually hairy, sometimes glabrous. Caryopses oblong, flattened dorsally, falling free; hila oblong, about 1/3 the length of the caryopses. x = 7. Named for John Torrey (1796-1873), an American botanist.

Torreyochloa grows in cold, wet, non-saline environments. It includes the two North American species treated below, plus two additional taxa in northeastern Asia (Koyama & Kawano 1964). Although similar to Glyceria and Puccinellia, Torreyochloa is not closely related to either (Soreng et al. 1990). It is readily distinguished from Glyceria by its open leaf sheaths, and from Puccinellia by the 7-9 (occasionally 5) prominent, rather than faint, lemma veins.


SELECTED REFERENCES Church, G.L. 1952. The genus Torreyochloa. Rhodora 54:197-200; Koyama, T. and S. Kawano. 1964. Critical taxa of grasses with North American and eastern Asiatic distribution. Canad. J. Bot. 42:859-884; Soreng, R.J., J.I. Davis, and J.J. Doyle. 1990 A phylogenetic analysis of chloroplast DNA restriction site variation in the Poaceae subfam. Pooideae. Pl. Syst. Evol. 172:83-97.

1
Mature inflorescences linear to narrowly elliptic, 0.3-1 cm wide, 5.5-19 times as long as wide; widest cauline blades 3.4-7.2 mm wide ..... 1. T. erecta
Mature inflorescences conic, ovoid, or obovoid, 1-16 cm wide, 1-7.5 times as long as wide; widest cauline blades 1.5-17.5 mm wide ..... 2. T. pallida


1.   Torreyochloa erecta (Hitchc.) G.L. Church
Spiked False Mannagrass

Culms 20-62 cm tall, 1-1.4 mm thick, usually erect. Ligules of larger cauline leaves 2.6-6.5 mm, truncate or rounded to acute; widest cauline blades 3.4-6(7.2) mm wide. Panicles 5.5-11 cm long, 0.3-1 cm wide, (5.5)6-19 times as long as wide, linear to narrowly elliptic; lowermost branches stiff to flexuous, reflexed to erect at maturity. Spikelets 4.2-6.4 mm; florets 4-6. Lower glumes 0.8-1.6 mm; upper glumes 1-2.1 mm; lemmas 2.3-3.1 mm, obtuse to acute; anthers 0.6-0.8 mm. 2n = 14.

Torreyochloa erecta grows at elevations above 2000 m, in the margins of subalpine and alpine lakes and streams of the Sierra Nevada and Cascade ranges.


2.   Torreyochloa pallida (Torr.) G.L. Church

Culms 18-145 cm tall, 0.6-4.8 mm thick, erect to decumbent, sometimes matted. Ligules of larger cauline leaves 2-9 mm, truncate or acute to attenuate; widest cauline blades 1.5-17.5 mm wide. Panicles (3)5-25 cm long, (1)1.8-16 cm wide, 1-5.75(7.5) times as long as wide, narrowly to widely conic, ovoid, or obovoid; lowermost branches stiff to flexuous, reflexed to erect at maturity. Spikelets 3.6-6.9 mm; florets 2-8. Lower glumes 0.7-2.1 mm; upper glumes 0.9-2.7 mm; lemmas 2-3.6 mm, truncate to acute; anthers 0.3-1.5 mm. 2n = 14.

All three varieties of Torreyochloa pallida grow in swamps, marshes, bogs, and the margins of lakes and streams. They are usually morphologically distinct and tend to have different geographic ranges.

1
Widest cauline blades 1.5-3 mm wide; anthers of lowest floret in each spikelet 0.3-0.6 mm long ..... var. fernaldii
Widest cauline blades 2.8-18 mm wide; anthers of lowest floret in each spikelet 0.5-1.5 mm long (2)
2
Anthers of lowest floret 0.7-1.5 mm long; basal diameter of culms 1.2-3 mm; upper glumes 1.4-2.7 mm; plants generally of eastern North America ..... var. pallida
Anthers of lowest floret 0.5-0.7 mm; basal diameter of culms (1.3)1.8-4.8 mm; upper glumes 0.9-1.8 mm; plants of western North America ..... var. pauciflora


Torreyochloa pallida var. fernaldii (Hitchc.) Dore
Fernald's False Mannagrass, Glycérie de Fernald

Culms 18-47 cm tall, 0.6-1.2 mm thick, erect to decumbent, matted. Ligules of larger cauline leaves 2-4 mm; widest cauline blades 1.5-3 mm wide. Panicles 5-8(9) cm long, 1.8-3(5) cm wide, 2.5-3.8 times as long as wide, conic to ovoid. Spikelets 4-4.8 mm; florets 2-5(7). Lower glumes 0.8-1.4 mm; upper glumes 1.3-1.6 mm; lemmas 2-2.4 mm, obtuse; anthers of lowest floret 0.3-0.6 mm.

Torreyochloa pallida var. fernaldii grows from Saskatchewan through southern Ontario and the Great Lakes area to New Brunswick and the New England states. Torreyochloa pallida var. fernaldii is often difficult to distinguish from T. pallida var. pallida where their ranges overlap.


Torreyochloa pallida (Torr.) G.L. Church var. pallida
Pale False Mannagrass

Culms 47-110 cm tall, 1.2-3 mm thick, erect to decumbent. Ligules of larger cauline leaves 5-8 mm; widest cauline blades 2.8-9(11.4) mm wide. Panicles (7.5)11-19 cm long, 3-16 cm wide, 1-4.1 times as long as wide, ovoid to ellipsoidal. Spikelets 3.6-6.5 mm; florets 2-6. Lower glumes 1-2.1 mm; upper glumes 1.4-2.7 mm; lemmas 2.4-3.6 mm, obtuse to acute; anthers of lowest floret 0.7-1.5 mm.

The range of Torreyochloa pallida var. pallida extends from southeastern Manitoba to north of Lake Superior and Maine, and south to Missouri and Georgia. Torreyochloa pallida var. pallida can be difficult to distinguish from T. pallida var. fernaldii.


Torreyochloa pallida var. pauciflora (J. Presl) J.I. Davis
Weak Mannagrass

Culms 20-145 cm tall, (1.3)1.8-4.8 mm thick, usually erect. Ligules of larger cauline leaves 3-9 mm; widest cauline blades 3.6-18 mm wide. Panicles (3)5-25 cm long, (1)2-14 cm wide, 1.2-5.75(7.5) times as long as wide, narrowly to widely conic, ovoid, or obovoid. Spikelets 3.6-6.9 mm; florets (3)4-8. Lower glumes 0.7-1.6 mm; upper glumes 0.9-1.8 mm; lemmas 2.2-3.3 mm, truncate or obtuse to acute; anthers of lowest floret 0.5-0.7 mm.

Torreyochloa pallida var. pauciflora grows in western North America, from sea level to 3500 m. Robust plants from Pacific lowland forests are often taller than 1 m; plants from farther east and higher elevations tend to be shorter.