14.28 POLYPOGON Desf.
Mary E. Barkworth
Plants annual or perennial; not rhizomatous. Culms 4–120 cm, erect to decumbent, rooting at the lower nodes, sparingly branched near the base. Leaves usually no more than 5 per culm, basal and cauline; sheaths open, smooth or scabridulous; auricles absent; ligules membranous or hyaline, acute to broadly rounded, erose, ciliate; blades flat to convolute. Inflorescences terminal panicles, dense, continuous or interrupted below; branches flexible, usually some longer than 1 cm; pedicels absent and the spikelets borne on a stipe, or present and terminating in a stipe; stipes scabrous, flaring distally; disarticulation at the base of the stipes. Spikelets 1–5 mm, weakly laterally compressed, with 1 bisexual floret; rachillas not prolonged beyond the base of the floret. Glumes exceeding the floret, lanceolate, bases not fused, apices entire to emarginate or bilobed, usually awned from the sinuses or apices, awns flexuous, glabrous, sometimes unawned; lemmas 1–3(5)-veined, often awned, awns usually terminal or subterminal, sometimes arising from just above midlength; paleas from 1/3 as long as to equaling the lemmas; lodicules 2, oblong-lanceolate to lanceolate; anthers 3; ovaries glabrous; styles separate. Caryopses slightly flattened, broadly ellipsoid to oblong-ellipsoid; hila 1/6–1/4 as long as the caryopses, ovate. x = 7. Name from the Greek poly, ‘many’ or ‘much’, and pogon, ‘beard’, an allusion to the bristly appearance of the inflorescence.
Polypogon is a pantropical and warm-temperate genus of about 18 species. There are eight species in the Flora region; one species, P. interruptus, is native.
Polypogon is similar to Agrostis, and occasionally hybridizes with it. It differs from Agrostis in having spikelets that disarticulate below the glumes, often at the base of a stipe.
SELECTED REFERENCE Cope, T.A. 1982. Flora of Pakistan, No. 143: Poaceae (E. Nasir and S.I. Ali, eds.). Pakistan Agricultural Research Council and University of Karachi, Islamabad and Karachi, Pakistan. 678 pp.
For an interactive dichotomous key click here, for an interactive multientry key click here.
1. Glumes with awns 3–12 mm long ..... 2
1. Glumes unawned or with awns to 3.2 mm long ..... 5
2. Glumes deeply lobed, the lobes more than 1/6 the length of the glume body ..... P. maritimus
2. Glumes not lobed or the lobes 1/10 or less the length of the glume body 3
3. Plants annual; glume apices rounded, lobed, the lobes 0.1–0.2 mm long; ligules 2.5–16 mm long ..... P. monspeliensis
3. Plants perennial; glume apices acute to truncate, unlobed or the lobes shorter than 0.1 mm; ligules 1–6 mm long ..... 4
4. Glume awns (3)4–6 mm long; longest blades 13–17 cm long 5. P. australis
4. Glume awns 1.5–3.2 mm long; longest blades 5–9 cm long 2. P. interruptus (in part)
5. Glumes unawned 1. P. viridis
5. Glumes awned, the awns 0.2–3.2 mm long ... 6
6. Stipes 1.5–2.5 mm long; glumes tapering from about midlength to the acute, unlobed apices 3. P. elongatus
6. Stipes 0.2–1.5 mm long; glumes not tapering to the apices, the apices usually rounded to truncate, sometimes acute, often lobed ..... 7
7. Lemmas 1–2 mm long; paleas about 1/2 as long as the lemmas; the lower glumes longer than the upper glumes ..... P. imberbis
7. Lemmas 0.7–1.5 mm long; paleas from 3/4 as long as to equaling the lemmas; glumes of each spikelet subequal to equal ..... 8
8. Plants annual; glumes acute to rounded, lobed, the lobes 0.1–0.2 mm long ..... P. fugax
8. Plants perennial, often flowering the first year; glumes acute to truncate, if lobed, the lobes to 0.1 mm long ..... P. interruptus (in part)
Polypogon viridis (Gouan) Breistr.
Plants perennial, often flower-ing the first year. Culms 10–90 cm, sometimes decumbent and rooting at the lower nodes. Sheaths glabrous, smooth; ligules to 5 mm; blades 2–13 cm long, 1–6 mm wide. Panicles 2–10 cm, ovate-oblong to pyramidal, dense but inter-rupted, pale green to purplish; pedicels not developed; stipes 0.1–0.6 mm. Glumes 1.5–2 mm, scabrous on the back and keel, apices obtuse or truncate, unawned; lemmas about 1 mm, erose, unawned; paleas subequal to the lemmas; anthers 0.3–0.5 mm. 2n = 28, 42.
Polypogon viridis grows in mesic habitats associated with rivers, streams, and irrigation ditches. It is native from southern Europe to Pakistan, but is now established in the Flora region, particularly the southwestern United States. Records from the Atlantic coast are based on plants found on ballast dumps; there have been no recent collections from these locations. The record from Oregon is based on a misidentified specimens of Agrostis stolonifera. The map will be corrected eventually.
In Europe, Polypogon viridis hybridizes with P. monspeliensis, forming P. ×adscendens Guss. ex Bertol.; no such hybrids have been reported from the Flora region.
Polypogon interruptus Kunth
Plants perennial, often flower-ing the first year. Culms 20–80 (90) cm, more or less decum-bent. Sheaths smooth; ligules 2–6 mm, scabridulous-pub-escent; blades 5–9 cm long, 3–6 mm wide. Panicles 3–15 cm long, 0.5–3 cm wide, usually interrupted or lobed; pedicels not developed; stipes 0.2–0.7 mm. Glumes 2–3 mm, subequal, scabrous, larger prickles extending up the keel beyond midlength, not tapering to the apices, apices acute to truncate, unlobed or the lobes to 0.1 mm, awned, awns 1.5–3.2 mm, those of the lower and upper glumes subequal; lemmas 0.8–1.5 mm, glabrous, smooth and shiny, apices obtuse, not emarginate, awned, awns 1–3.2 mm; paleas about 3/4 as long as the lemmas; anthers 0.5–0.7 mm. 2n = 28, 42.
Polypogon interruptus grows in moist soil at lower elevations. It is native to the Western Hemisphere, extending south from the western United States into northern Mexico, and through the American tropics to Argentina and Bolivia. The more eastern records may indicate introductions; it is not known whether or not the species persists at these locations.
Polypogon elongatus Kunth
Plants perennial, often flower-ing the first year. Culms to 100 cm, erect or decumbent at the base. Sheaths smooth, glabrous; ligules 4–8 mm, scabridulous, lacerate; blades 10–30 cm long, 4–15 mm wide. Panicles 10–30 cm, erect or nodding, inter-rupted, dense; pedicels not developed; stipes 1.5–2.5 mm. Glumes 3–5 mm, hispidulous, tapering from about midlength to the acute apices, apices unlobed, awned, awns 1–3 mm; lemmas about 1.5 mm, awned, awns 1–2 mm, arising from above midlength; paleas 1/2–2/3 as long as the lemmas; anthers 0.5–0.7 mm. 2n = 28, 56.
Polypogon elongatus is native from Mexico to Argentina. It now grows at scattered locations in the Flora region, primarily in California.
Polypogon fugax Nees ex Steud.
Plants annual. Culms (8.5) 15–60 cm, often decumbent at the base and rooting at the nodes. Sheaths smooth; ligules 2–8 mm; blades 2–16 cm long, 2–11 mm wide, scabrous. Panicles 3–15 cm long, 0.5–5 cm wide, narrowly ovoid, oblong, or cylindrical, dense, usually lobed, pale green or yellowish; pedicels absent or to 0.5 mm; stipes 0.2–1.3 mm. Glumes 1.8–2.4 mm, equal to subequal, scabridulous to echinate, not tapering to the apices, apices acute to rounded, lobed, lobes 0.1–0.2 mm, awned from the sinuses, awns 0.6–3 mm, those of the lower and upper glumes subequal to equal, flexuous; lemmas 0.9–1.2 mm, smooth, unawned or awned, awns to 2 mm, flexuous; paleas 0.7–1.2 mm, from 3/4 as long as to equaling the lemmas; anthers 0.3–0.6 mm. 2n = 42.
Polypogon fugax is native from Iraq to Myanmar [Burma]. It was collected in Santa Barbara, California, and from salt marshes around Oakland, California, in the nineteenth century, and from Portland, Oregon, in the early twentieth century. There are no recent collections from the Flora region.
Polypogon australis Brongn.
Plants perennial. Culms 20–100 cm. Sheaths smooth to scab-ridulous; ligules 1–3(4) mm, rounded to broadly acute, erose; blades 13–17 cm long, 5–7 mm wide, scabrous. Panicles 8–15 cm, lobed or interrupted, usually purplish; pedicels absent or vestigial; stipes 0.3–0.5 mm. Glumes 1.5–3 mm, smooth to echinate, margins ciliate, apices acute to truncate, unlobed or lobed, lobes to 0.1 mm, awned, awns (3)4–6 mm, flexuous; lemmas 1–1.3 mm, awned, awns 2–3.5 mm, flexuous; paleas from shorter than to subequal to the lemmas; anthers 0.3–0.5 mm. 2n = unknown.
Polypogon australis is native to South America. It has become established in western North America, where it grows alongside ditches and streams. The records from Washington and Oregon are from ballast dumps; it is not known from recent collections in those states.
Polypogon monspeliensis (L.) Desf.
Plants annual. Culms 5–65 (100) cm, erect to geniculately ascending. Sheaths glabrous, the uppermost sheaths some-times inflated; ligules 2.5–16 mm; blades 1–20 cm long, 1–7 mm wide. Panicles 1–17 cm, narrowly ellipsoid, dense, some-times lobed, greenish; pedicels absent or to 0.2 mm; stipes 0.1–0.2 mm. Glumes 1–2.7 mm, hispidulous throughout, largest prickles restricted to the lower 1/2, apices rounded, lobed, lobes 0.1–0.2 mm, 1/10 or less the length of the glume body, awned from the sinus, awns 4–10 mm, yellowish; lemmas 0.5–1.5 mm, glabrous, awned, awns 0.5–1(4.5) mm; paleas subequal to the lemmas; anthers 0.2–1 mm. 2n = 14, 28, 35, 42.
Polypogon monspeliensis is native to southern Europe and Turkey. It is now a common weed throughout the world, including much of the Flora region. It grows in damp to wet, often alkaline soils, particularly in disturbed areas. Vernon Harms (pers. comm., 2005) commented that the species’ distribution in Saskatchewan appears to have increased greatly since the 1970s. The English-language name aptly describes the feel of the young panicles.
In Europe, Polypogon monspeliensis hybridizes with Agrostis stolonifera, producing the sterile ×Agropogon lutosus ; and with P. viridis, forming P. ×adscendens Guss. ex Bertol. Only ×Agropogon lutosus has been reported from the Flora region. It differs from P. monspeliensis in having more persistent spikelets, less blunt short-awned glumes, and lemmas with sub-terminal rather than terminal awns.
Polypogon maritimus Willd.
Plants annual. Culms (5)20–40 (50) cm, geniculate. Sheaths glabrous, smooth, uppermost sheaths sometimes inflated; ligules to 7 mm; blades (1)3–9 (14) cm long, 0.5–5 mm wide. Panicles (1)2–8(15) cm, nar-rowly ellipsoid, dense, some-times lobed, often purplish; pedicels to about 0.5 mm, capillary; stipes 0.1–1.2 mm. Glumes 1.8–3.2 mm, hispidulous basally, hairs sometimes strongly inflated and obtuse, apices lobed, lobes 0.3–1.2 mm, more than 1/6 the length of the glume body, awned from the sinus, awns (4)7–12 mm; lemmas 0.5–1.5 mm, unawned or awned, awns shorter than 1 mm; paleas subequal to the lemmas; anthers 0.4–0.5 mm. 2n = 14.
Polypogon maritimus grows in disturbed, moist places, from sea level to 700 m. It is a Mediterranean species that now occurs at scattered locations in North America, being particularly common in, or possibly just well-reported from, California. There are two varieties. Plants from the Flora region belong to P. maritimus Willd. var. maritimus, having stipes about as long as they are wide, glumes that never become strongly indurate at the base, and uninflated, acute hairs on the glume bases. Plants of P. maritimus var. subspathaceus (Req.) Bonnier & Layens have stipes that are 3–4 times as long as wide, glumes that become strongly indurate at maturity, and hairs on the glume bases that are strongly inflated and subobtuse.
Polypogon imberbis (Phil.) Johow
Plants perennial. Culms 15–80 cm, ascending or geniculate, not branched. Sheaths smooth or scabrous; ligules 2–5 mm, membranous or hyaline, some-times retrorsely scabridulous; blades 3–15 cm long, 1.5–8 mm wide, flat to convolute, scab-rous, apices acute to sharp. Panicles 3–25 cm long, 1–8 cm wide, dense, glomerate, interrupted near the base; pedicels not developed; stipes 0.6–1.5 mm. Glumes 1.8–4 mm, scabridulous on the sides, keels echinate, not tapering to the apices, apices acute, unlobed, awned, awns 0.2–2.5 mm; lower glumes 1.8–4 mm; upper glumes 1.6–3.5 mm, usually shorter than the lower glumes; lemmas 1–2 mm, hyaline, unawned or awned, awns subterminal, to 1 mm; paleas 0.5–0.8 mm, about 1/2 as long as the lemmas; anthers 0.2–0.8 mm. Caryopses 1–1.5 mm long, 0.3–0.4 mm wide. 2n = unknown.
Polypogon imberbis is a South American species that has been collected at two locations in California, one from Oceano Beach, San Luis Obispo County, and the other near Martines, Contra Costa County. It does not appear to be established there, the last collections having been made before 1950. In South America, it grows in moist, sandy soils near streams, lagoons, and the coast.