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Pacific brome

rattlesnake brome, rattlesnake chess, rattlesnake grass

Habit Plants perennial; not rhizomatous. Plants annual.
Culms

60-170 cm, erect;

nodes (5)6-8, pubescent;

internodes usually glabrous, sometimes pubescent near the nodes.

20-62 cm, erect or ascending.

Sheaths

pilose, midrib of the culm leaves not abruptly narrowed just below the collar;

auricles absent;

ligules 2-4 mm, glabrous, truncate, erose or lacerate;

blades 20-35(37) mm long, 6-16 mm wide, flat, abaxial surfaces glabrous, adaxial surfaces pilose.

densely pilose;

ligules 0.5-2 mm, hairy, obtuse, erose;

blades 3-13 cm long, 2-4 mm wide, pilose to pubescent on both surfaces.

Panicles

10-25 cm, open, nodding;

branches ascending, spreading, or drooping.

5-15 cm long, 3-7 cm wide, open, secund, nodding;

branches sometimes longer than the spikelets, curved to reflexed.

Spikelets

20-30 mm, elliptic to lanceolate, terete to moderately laterally compressed, with (4)6-10 florets.

15-27 mm long, 8-12 mm wide, ovate, laterally compressed;

florets 7-15, bases concealed at maturity;

rachilla internodes concealed at maturity.

Glumes

pubescent;

lower glumes 6-8.5 mm, 1(3)-veined;

upper glumes 8-11.5 mm, 3-veined, not mucronate;

lemmas 10-12 mm, lanceolate, rounded over the midvein, backs pubescent, margins more densely so, apices acute, entire;

awns 3.5-7 mm, straight, arising less than 1.5 mm below the lemma apices;

anthers 2-4 mm.

smooth or scabridulous;

lower glumes 5-6 mm, 3-5-veined;

upper glumes 6-8 mm, 7-9-veined;

lemmas 9-10 mm long, 6-8 mm wide, inflated, obovate or rhombic, coriaceous, smooth or scabridulous, obscurely 9-veined, rounded over the midvein, margins hyaline, 1-1.3 mm wide, abruptly angled, not inrolled at maturity, apices acute to obtuse, bifid, teeth shorter than 1 mm;

awns usually absent, sometimes to 1 mm, arising less than 1.5 mm below the lemma apices;

anthers 0.7-1 mm.

Caryopses

equaling or shorter than the paleas, thin, weakly inrolled or flat.

2n

= 28.

= 14.

Bromus pacificus

Bromus briziformis

Distribution
from FNA
AK; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; CA; CO; CT; DE; ID; IL; IN; MA; MD; MI; MT; ND; NE; NJ; NM; NV; NY; OH; OR; PA; SD; UT; VT; WA; WY; BC; ON
[WildflowerSearch map]
[BONAP county map]
Discussion

Bromus pacificus grows in moist thickets, openings, and ravines along the Pacific coast from southeastern Alaska to northern California, with a few occurrences further inland.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Bromus briziformis grows in waste places, road verges, and overgrazed areas. It is native to southwest Asia and Europe, and is adventive in the Flora region, occurring from southern British Columbia to as far south as New Mexico, and in scattered locations eastward. The unique shape of its spikelets has led to its use in dried flower arrangements and as a garden ornamental. The common name may refer to the similarity of the spikelets to a rattlesnake's tail.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 24, p. 218. FNA vol. 24, p. 228.
Parent taxa Poaceae > subfam. Pooideae > tribe Bromeae > Bromus > sect. Bromopsis Poaceae > subfam. Pooideae > tribe Bromeae > Bromus > sect. Bromus
Sibling taxa
B. aleutensis, B. anomalus, B. arenarius, B. arizonicus, B. arvensis, B. berteroanus, B. briziformis, B. carinatus, B. caroli-henrici, B. catharticus, B. ciliatus, B. commutatus, B. danthoniae, B. diandrus, B. erectus, B. frondosus, B. grandis, B. hallii, B. hordeaceus, B. inermis, B. japonicus, B. kalmii, B. laevipes, B. lanatipes, B. lanceolatus, B. latiglumis, B. lepidus, B. madritensis, B. maritimus, B. mucroglumis, B. nottowayanus, B. orcuttianus, B. polyanthus, B. porteri, B. pseudolaevipes, B. pubescens, B. pumpellianus, B. racemosus, B. ramosus, B. richardsonii, B. riparius, B. rubens, B. scoparius, B. secalinus, B. sitchensis, B. squarrosus, B. sterilis, B. suksdorfii, B. tectorum, B. texensis, B. vulgaris
B. aleutensis, B. anomalus, B. arenarius, B. arizonicus, B. arvensis, B. berteroanus, B. carinatus, B. caroli-henrici, B. catharticus, B. ciliatus, B. commutatus, B. danthoniae, B. diandrus, B. erectus, B. frondosus, B. grandis, B. hallii, B. hordeaceus, B. inermis, B. japonicus, B. kalmii, B. laevipes, B. lanatipes, B. lanceolatus, B. latiglumis, B. lepidus, B. madritensis, B. maritimus, B. mucroglumis, B. nottowayanus, B. orcuttianus, B. pacificus, B. polyanthus, B. porteri, B. pseudolaevipes, B. pubescens, B. pumpellianus, B. racemosus, B. ramosus, B. richardsonii, B. riparius, B. rubens, B. scoparius, B. secalinus, B. sitchensis, B. squarrosus, B. sterilis, B. suksdorfii, B. tectorum, B. texensis, B. vulgaris
Synonyms Bromopsis pacifica B. brizaeformis
Name authority Shear Fisch. & C.A. Mey.
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