Bromus arizonicus (Shear) Stebbins

Saarela, Jeffery M., Peterson, Paul M. & Valdés-Reyna, Jesus, 2014, A taxonomic revision of Bromus (Poaceae: Pooideae: Bromeae) in México and Central America, Phytotaxa 185 (1), pp. 1-147: 24-28

publication ID

http://doi.org/ 10.11646/phytotaxa.185.1.1

DOI

http://doi.org/10.5281/zenodo.5156650

persistent identifier

http://treatment.plazi.org/id/0389862D-DE71-006C-E3DB-F91FE4C11F92

treatment provided by

Felipe

scientific name

Bromus arizonicus (Shear) Stebbins
status

 

2. Bromus arizonicus (Shear) Stebbins   in Stebbins et al. (1944: 309). Figs. 5, 6.

Basionym: Bromus carinatus var. arizonicus Shear (1900: 62)   . Ceratochloa arizonica (Shear) Holub (1973: 170)   . Type:— UNITED STATES OF AMERICA. Arizona: Pima Co., Tucson, Santa Cruz Valley, 3 May 1884, C.G. Pringle s.n. (holotype US-81568!, isotypes GH-00023238!, MIN-1000471!, PH-01038760!, PH-01050337!).

Plants annual, tufted. Culms (8–) 30–90 cm tall, (1–) 1.5–2 mm wide at base, erect, glabrous below inflorescences; nodes 2–4, glabrous or weakly pubescent. Leaf sheaths puberulent to pubescent, hairs up to 1 mm long; ligules

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SAARELA ET AL.

1–2.1(–3) mm long; auricles absent; blades up to 30 cm × (1.5–) 2–6 mm, flat, abaxial and adaxial surfaces pilose, sometimes glabrous, hairs up to 0.6 mm long, margins serrulate. Panicles (3–) 5–30 cm × 1–2(–3) cm, erect, ± contracted, at least when young, branches erect to ascending, scabrous, often shorter than spikelets, 1–2 spikelets per branch. Spikelets 1.5–2.5(–2.7) cm long, 4–9-flowered, elliptic to lanceolate, strongly laterally compressed; glumes glabrous or scabrous, margins hyaline, midnerves glabrous proximally, scabrous distally, apices acute; lower glumes (6–) 8–13 mm long, lanceolate, 3–5-nerved, green to purplish-green along and between nerves; upper glumes (7–) 9–15 mm long, ± equal in length to the lowest lemma, ovate-lanceolate, 5–9-nerved, green to purplishgreen along and between the nerves; lemmas 9.5–14 mm long, lanceolate, strongly keeled, apices acute, margins usually weakly to moderately pubescent throughout or distally, sometimes scabrous to short-pubescent, hairs up to 0.5 mm long, backs glabrous, scabrous or pubescent, hairs usually shorter than those along margins, midnerves glabrous to scabrous distally, margins hyaline; awns (4–) 7–15 mm long, inserted up to 0.5(–0.6) mm below the lemma apex, straight; paleas shorter and narrower than lemmas, backs glabrous, keels ciliate, cilia up to 0.1 mm long; anthers 0.4–0.5 mm long; caryopses 8−9.5 mm long. 2 n = 84 ( Stebbins et al. 1944, Klos et al. 2009).

Distribution:―Native. In México this species is known only from Baja California and Sonora ( Fig. 7). Its range includes California, southwest Nevada and New México ( Pavlick & Anderton 2007). There are numerous collections of B. arizonicus   on the border of Sonora and Arizona (R. Felger, pers. comm. 2014). Its distribution in Sonora is likely broader than shown here. In addition to Baja California and Sonora, Espejo-Serna et al. (2000) reported this species from Coahuila; this report is likely based on a misidentification. For example, Palmer 266, collected in Saltillo, Coahuila, and determined as B. arizonicus   by Beetle in 1972, was found to be B. carinatus   upon examination.

ATAXONOMIC REVISION OF BROMUS (POACEAE)  

Phytotaxa 185 (1) © 2014 Magnolia Press 25

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SAARELA ET AL.

Ecology: —This species is a winter-spring ephemeral and occurs in stabilized sand dunes, on slopes, along dried creek bottoms and roadsides often on volcanic soils; associated with Fouquieria columnaris ( Kellogg 1860: 101) Kellogg ex Curran (1885: 133)   and Ambrosia dumosa   (A. Gray in Frémont 1845: 316) Payne (1964: 422). Elevation: 10–1124 m.

Common Names: ― Arizona brome (English).

Comments: ― Bromus arizonicus   is a duocecaploid, and Stebbins et al. (1944) hypothesized that it may be an intersubgeneric allopolyploid derived from B. catharticus   (sect. Ceratochloa   ) and the hexaploid B. berteroanus   (sect. Neobromus), or an unknown close relative of the latter. It can be difficult to distinguish from B. carinatus   (octoploid), from which it differs by its annual habit, upper glumes that are approximately equal in length to the lowest lemmas and lemmas usually with hairs along the margins. Also, most branches are shorter than their spikelets, resulting in erect and narrow inflorescences. This latter characteristic is not helpful for distinguishing the species in Baja California, as most individuals of B. carinatus   from this region also have narrow, short-branched inflorescences. Elsewhere in México panicles of B. carinatus   are more open with longer branches.

Some authors have treated B. arizonicus   as a synonym of B. carinatus   . Soderstrom & Beaman (1968) were not able to distinguish the taxa in Baja California, and treated all plants as B. carinatus   , including two cited in the protologue of B. arizonicus: Wiggins   5291 and Epling & Stewart s.n. Several specimens at SD determined as B. carinatus var. arizonicus   by F.W. Gould in 1978, but later determined as " Bromus carinatus   H. & A., near B. marginatus Nees   " by G.L. Stebbins in 1980 ( Gould & Moran 1981), are readily identifiable as B. arizonicus   (Gentry & Cech 8875, Purer 7166A, Moran 16999, 16930, 16880, 6551). Specimens from the Sonoran desert in Arizona were recently found to be difficult to distinguish, except as ephemeral (annual) vs. perennial (R. Felger pers. comm. 2014, Felger 2014; also see comments of J.R. Reeder in Halvorson & Guertin 2003).

Specimens Examined:― MÉXICO. Baja California: 2.0 km Nof Colonia Guerrero, [30.75°N, 116°W], 80 m, 3 April 1958, P. H GoogleMaps   . Raven , H   . Lewis & H   . Thompson 12141 ( GH); 16 km SE of El Rosario, 30°N, 115.6167°W, 210 m, 18 April 1958, P. H GoogleMaps   . Raven , M   . Mathias & J   . Turner 12496 ( GH); 24.3 mi Eof Rosario, 32.3333°N, 116.62°W, 11 April 1931, I. L GoogleMaps   . Wiggins 5291 ( GH, MICH-1119175, NY, RSA-POM-265012, US)   ; 7–8 mi Sof Punta Prieta , 28.86°N, 114.2833°W, 29 March 1973, H. S GoogleMaps   . Gentry & F   . Cech 8875 ( MICH-1119163, RSA-POM- 5688867, SD-86524, US-2079818); Arroyo Agua Amarga, southern San Pedro Mártir , 30.75°N, 115.2167°W, 823 m, 13 May 1941, I. L GoogleMaps   . Wiggins 9952 ( US-1842711); Isla del Norte, Los Coronados , [32.4167°N, 117.25°W], 20 March 1966, R. N GoogleMaps   . Philbrick & E. R   . Blakley B66-223 ( RSA-POM-638847); Isla San Martín , [30.5°N, 116.1167°W], ca. 60 m, 1 April 1988, R. F GoogleMaps   . Thorne 63172 ( RSA-POM-500962); Rosario Wash , 10 April 1931, I. L   .

ATAXONOMIC REVISION OF BROMUS (POACEAE)  

Phytotaxa 185 (1) © 2014 Magnolia Press 27

Wiggins 5241 (MICH-1119179, NY, GH, US-1721766); S Coronado Island , [32.4167°N, 117.25°W], 50 ft, 19 March 1966 GoogleMaps   , E. R. Blakley 6702 ( RSA-POM-638849); Santa Catarina Landing , [29.5926°N, 115.258°W], 10 March 1930 GoogleMaps   , I. L. Wiggins 4425 ( MICH-1119180, US-1721772); San Quintín , 17 April 1958   , [30.5602°N, 115.9425°W], 30 m, P. H. Raven   , M. Mathias   & J. Turner 12346 ( GH); San Quintín , [30.5602°N, 115.9425°W], 5 April 1936 GoogleMaps   , C. Epling & Wm. Stewart s.n. ( MICH-1119270); Arroyo Socorro, Socorro wash, 16 mi Eof Hwy. 1, [30.3167°N, 115.8167°W], 24 April 1984 GoogleMaps   , P. M. Peterson   & C. R. Annable 02273 ( CAN, US); 1 km Eof El Morro , 32.2583°N, 116.9792°W, 10 m, 27 March 1982 GoogleMaps   , R. Moran 30069 ( SD-110770); Santo Tomás, near Paloma Rch Trailer Park , [31.57°N, 116.52°W], 180 m, 16 September 1979 GoogleMaps   , J. R. Reeder   & C. G. Reeder 7215 ( SD-116029); Tijuana River bottom, 32.5333°N, 117.0167°W, 20 m, 18 April 1981 GoogleMaps   , R. Moran 29552 ( SD-108517); Coronado Islands   , N Island, on top, 32.4375°N, 117.3°W, 100 m, 20 March 1958 GoogleMaps   , R. Moran 6551 ( SD-49332); Sof Playa Hotel, Ensenada, 31.8667°N, 116.6167°W, 25 March 1937 GoogleMaps   , E. A. Purer 7166   A ( US-1648131, SD-39682); 2 mi SE of El Progreso , 29.4667°N, 115.1667°W, 490 m, 25 March 1970 GoogleMaps   , R. Moran 16880 ( SD-76758); Puerto Santa Catarina , 29.5167°N, 115.2667°W, 5 m, 27 March 1970 GoogleMaps   , R. Moran 16999 ( SD-76828); Arroyo Santa Catarina, Ammonite area 5 mi   Nof the mouth of arroyo, 29.5833°N, 115.2333°W, 75 m, 26 March 1970 GoogleMaps   , R. Moran 16930 ( SD-76816); Coronado Islands   , N Grande Island, [32.4467°N, 117.2983°W], 25 March 1990 GoogleMaps   , T. Oberbauer 90-30 ( SD-162832); Coronado Islands   , Eslope above landing on N island, 32.4467°N, 117.2983°W, 50 m, 3 March 1970 GoogleMaps   , R. Moran 16795 ( SD- 76240); Mpio. Ensenada, City of Ensenada , 31.8606°N, 116.6178°W, 31 March 2007 GoogleMaps   , F. Casillas 73 ( SD-182569); Ensenada, Todos Santo Bay , 31.8606°N, 116.6178°W, 21 March 1948 GoogleMaps   , H. S. Gentry 7911 ( RSA-POM-364157); Cuesta de Jarahuai and vicinity, 732–914 m, 31.6°N, 116.3833°W, 6 April 1950 GoogleMaps   , H. S. Gentry   & F. Cech 9005 ( ARIZ-265015, MICH-1119162, US-2810955, US-2079823); Arroyo Cataviña , in bed of arroyo near the mouth, 29.4167°N, 115.1°W, 10 m, 29 March 1970 GoogleMaps   , R. Moran 17048 ( MSC-276930, SD-76825). Sonora: Mpio. Elías Calles. 16.6 km on Mex. Hwy 8 SW of Sonoyta, 31º47’30”N, 112º59’15”W, 415 m, 29 April 1991 GoogleMaps   , Felger 91-56 ( ARIZ-327325, det. R. Felger, 2014); Imuris , 30.7833°N, 110.8583°W, 840 m, 31 May 1995 GoogleMaps   , T. R. Van Devender   95-546 ( ARIZ-319529, det. R. Felger 2014)   .

Nof

Nanjing University

P

Museum National d' Histoire Naturelle, Paris (MNHN) - Vascular Plants

H

University of Helsinki

GH

Harvard University - Gray Herbarium

M

Botanische Staatssammlung München

J

University of the Witwatersrand

Eof

Royal Botanic Garden Edinburgh

I

"Alexandru Ioan Cuza" University

L

Nationaal Herbarium Nederland, Leiden University branch

NY

William and Lynda Steere Herbarium of the New York Botanical Garden

Sof

Department of Botany, Swedish Museum of Natural History

S

Department of Botany, Swedish Museum of Natural History

F

Field Museum of Natural History, Botany Department

R

Departamento de Geologia, Universidad de Chile

N

Nanjing University

E

Royal Botanic Garden Edinburgh

C

University of Copenhagen

G

Conservatoire et Jardin botaniques de la Ville de Genève

A

Harvard University - Arnold Arboretum

T

Tavera, Department of Geology and Geophysics

Kingdom

Plantae

Phylum

Tracheophyta

Class

Liliopsida

Order

Poales

Family

Poaceae

Genus

Bromus