Bromus diandrus Roth, Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Bromus rigidus Roth

Common name(s): [more details]

Chinese: ying que mai

English: broncho grass, giant brome, great brome, ripgut brome, ripgut grass, slands grass

French: brome raide

Spanish: barba de macho

Habit:  grass

Description: 

Bromus diandrus Roth:  "Annuals, 20-90 cm, loosely tufted or consisting of a solitary culm. Leaf-sheath with soft, short, spreading hairs; upper sheaths ± glabrous near base. Ligule 1.5-4 mm, denticulate to lacerate. Leaf-blade 4-30 cm x 2-7 mm, with short, ± scattered hairs, scabrid near acute tip. Culm 10-65 cm, erect or ascending, internodes with very short hairs below nodes and below panicle. Panicle 10-28 cm, very lax and nodding; branches spreading, slender, scabrid, tipped by 1-(2) spikelets. Spikelets 5.5-9.5 cm, 5-8-flowered, oblong-lanceolate to later wedge-shaped and gaping, greyish green to purplish. Glumes unequal, very narrow, acuminate, membranous, glabrous, but sparsely scabrid on keels and nerves in upper 1/2; lower 13-22 mm, 1-(3)-nerved, upper 20-30 mm, 3-(5)-nerved. Lemma 20-35 mm, 7-nerved, rounded, lanceolate, minutely scabrid, tapering to 2 acute to acuminate, hyaline, smooth to finely scabrid lobes 4-5 mm; awn 30-60 mm. Palea c. 2/3 length of lemma, keels sparsely ciliate. Callus with minute hairs. Rachilla 4-6 mm, finely, minutely scabrid. Stamens 2-3; anthers 1-3 mm. Caryopsis 11-13 x 1.5-2.8 mm"  (Edgar & Connor, 2000; p. 362).

Description from GrassBase.

Bromus diandrus Roth var. rigidus (Roth) Sales:  "Annuals, culms 4-7 (-9) dm tall, solitary or sparsely tufted, pubescent for ca. 15 cm below panicle.  Sheaths 2-10 cm long, pilose; ligule 2-4 (-5.5) mm long, membranous, erose-lacerate; blades flat, 2-6 (-8) mm wide, sometimes involute, pilose, auricles absent.  Inflorescences paniculate, (7-) 10-20 cm long, open, the branches elongate, erect or spreading, sometimes the lowermost reflexed; spikelets (3) 4-6 (-8)-flowered, (28-) 33-40 (-43) mm long; glumes scabrous, linear to narrowly lanceolate, first glume 13-18 (-22) mm long, 1 (-3)-nerved; lemmas (22-) 25-30 mm long, 1-1.5 mm wide in side view, scabrous to puberulent, the narrow apical teeth 3-6 mm long, awns (30-) 35-60 mm long; palea slightly shorter than lemma, ciliate on the 2 keels, adhering to caryopsis.  Caryopsis golden brown, narrow, 10-15 mm long"  (Wagner et al., 1999; p. 1508).

Habitat/ecology:  In Hawai‘i, "naturalized and common in pastures, subalpine forest and shrubland, and disturbed areas, (5-) 550-2,270 m"  (Wagner et al., 1999; p. 1508).  "In Chile this species grows in the following environmental conditions:  Low altitude, interior valleys; coastal mountains, 500-2000 m; coastal areas, 0-500 m.  Somewhat dry areas where the drought may last 3-5 months, precipitations of 400 - 800 mm. are concentrated in winter.  Fully exposed to the sun, level areas or slopes facing north"  (Chileflora).

Propagation:  Seed

Native range:  The Mediterranean region (Wagner et al., 1999; p. 1508).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia (Pacific offshore islands) Lord Howe Island	Lord Howe Island	introduced invasive	Orchard, Anthony E., ed. (1994) (p. 22) "A fairly common weed of poor pastures, roadsides etc." Vouchers cited: R.D. Hoogland 8658 (CANB), P.S. Green 1643 (A, K), A.C. Beauglehole 5430 (CANB, MEL)
Australia (Pacific offshore islands) Norfolk Islands	Norfolk Island	introduced invasive	Orchard, Anthony E., ed. (1994) (p. 12) "A fairly common weed of poor pastures, roadsides etc." Vouchers cited: P.S. Green 1478 (A), W.R. Sykes 772/87 (CHR), W. Laing (CHR)
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive	Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive	Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (pp. 460, 463, 551) Voucher cited: Danton I(5/192)1525
Chile (offshore islands) Juan Fernández Islands	Isla Más Afuera (Alejandro Selkirk Island)	introduced invasive	Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands) Juan Fernández Islands	Isla Más Afuera (Alejandro Selkirk Island)	introduced invasive	Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (pp. 460, 463, 551)
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1508) As Bromus rigidus [=Bromus diandrus Roth var. rigidus (Roth) Sales]; voucher cited: Rock 8403 (BISH)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1508) As Bromus rigidus [=Bromus diandrus Roth var. rigidus (Roth) Sales]
State of Hawaii Hawaiian Islands	Lāna‘i Island	introduced invasive	Oppenheimer, Hank (2008) (p. 32) Voucher cited: Oppenheimer, Perlman & Tangalin H30714 (BISH, PTBG)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Herbarium Pacificum Staff (1999) (p. 7) East Maui. As Bromus rigidus [=Bromus diandrus Roth var. rigidus (Roth) Sales]; voucher cited: C. Imada, W. Char & C. Morden 98-11
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Starr, Forest/Starr, Kim (2011) (p. 32) East Maui. Voucher cited: Starr & Starr 090628-01 (BISH)
New Zealand (offshore islands) Kermadec Islands	Kermadec Islands	introduced invasive	Edgar, E./Connor, H. (2000) (p. 362) "Roadsides and waste ground, often in sandy ground".

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	Australia (continental)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 35)
China China	China (People's Republic of)	introduced invasive	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) As Bromus rigidus Roth. Streamsides, moist places; ca. 1000 m. Jiangxi
China China	China (People's Republic of)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 41) As Bromus rigidus [=Bromus diandrus Roth var. rigidus (Roth) Sales]
New Zealand New Zealand	New Zealand (country)	introduced invasive	Edgar, E./Connor, H. (2000) (p. 362) "Roadsides and waste ground, often in sandy ground".
South America (Pacific rim) South America (Pacific rim)	Chile (Republic of)	introduced invasive	Belov, Michail (2013)
Taiwan Taiwan Island	Taiwan Island	introduced invasive	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) As Bromus rigidus Roth. Streamsides, moist places; ca. 1000 m.

Control:  If you know of control methods for Bromus diandrus, please let us know.