BEN
BOTANICAL ELECTRONIC NEWS
ISSN 1188-603X

No. 415 October 6, 2009 aceska@telus.net Victoria, B.C.
Dr. A. Ceska, P.O.Box 8546, Victoria, B.C. Canada V8W 3S2

TAXONOMY OF BROMUS SECTIONS BROMUS, BROMOPSIS AND GENEA (POACEAE) IN BRITISH COLUMBIA: A SUMMARY, A KEY, NEW RECORDS, SPECIMEN CITATIONS, AND MISCELLANEOUS NOTES

From: Jeffery M. Saarela, Canadian Museum of Nature, Ottawa, Ontario K1N 8A5 [jsaarela@mus-nature.ca] See: http://bomi.ou.edu/ben/415/ for Figure 1 to 3 and Appendix 1

Note: The introductory text and taxonomic key are adapted and modified from the following paper, courtesy of the Journal of the Botanical Research Institute of Texas:

Saarela, J. M. 2008.
Taxonomy of Bromus (Poaceae: Pooideae: Bromeae) sections Bromopsis, Bromus, and Genea in British Columbia, Canada. Journal of the Botanical Research Institute of Texas 2, 323-372. [Please, contact the author if you would like a hard copy reprint or PDF of this paper.]

Bromus L. is a large and taxonomically complex grass genus that includes more than 160 species distributed in temperate regions worldwide. The genus is distinguished from other grass genera by the combination of leaf sheaths that are closed for most of their length, awns that are inserted subapically, and hairy appendages on the apices of the ovary (Clayton & Renvoize 1986). Approximately 80 Bromus species are currently recognized in North, Central, and South America (Pavlick et al. 2003); 29 of these reportedly occur in Canada (Pavlick & Anderton 2007). In Canada, British Columbia has the greatest number of Bromus species. It is the second-largest grass genus in British Columbia; only Poa L., with 31 species (Soreng 2007), has greater species richness in the province.

There has been considerable progress in clarifying lower-level taxonomic problems in Bromus. Several taxa that occur in North American have received recent taxonomic study, including: B. ciliatus L. and B. richardsonii Link (Peterson et al. 2002); B. grandis (Shear) Hitchc., B. hallii (Hitchc.) Saarela & P.M. Peterson and B. orcuttianus Vasey (Saarela et al. 2005); Bromus catharticus var. elatus (E. Desv.) Planchuelo (Planchuelo 2006); and B. carinatus Hook. & Arn. (Barkworth et al. 2006). Comprehensive taxonomic treatments of Bromus for North America north of Mexico have recently been published (Pavlick 1995; Pavlick & Anderton 2007). Despite these resources, identifying species of Bromus can be a notoriously difficult exercise for many workers. In such large and difficult groups, geographically focused taxonomic treatments can greatly facilitate accurate identifications and provide more detailed information than is normally found in standard floras, be they regional or continental in scope.

The most recent comprehensive treatment of Bromus for British Columbia, in Illustrated Flora of British Columbia (Douglas et al. 2001), takes a taxonomically conservative approach and does not reflect current understanding of the genus. Another recent treatment for the province (Stewart & Hebda 2000) is restricted geographically to only those species that occur in the Columbia Basin region in southeastern British Columbia. In Saarela (2008) and here I provide a detailed and updated taxonomic treatment for Bromus in British Columbia, including a dichotomous key, synonymies, species descriptions, distribution maps and citations of representative specimens.

Bromus in British Columbia

Bromus in British Columbia includes multiple native and introduced species that are currently classified in four sections (the genus-level taxonomy is reviewed by Saarela et al. 2007). Most of the introduced species are annuals classified in Bromus. sects. Bromus (B. briziformis Fisch. & C.A. Mey., B. commutatus Schrad., B. hordeaceus L., B. japonicus Thunb., B. racemosus L., B. secalinus L. and B. squarrosus L.) and Genea Dumort. (B. diandrus Roth, B. sterilis L. and B. tectorum L.). All of these (and other) introduced species in Bromus sects. Bromus and Genea occur throughout western North America, mostly north of Mexico (see Pavlick & Anderton 2007; Saarela & Peterson in press), and several have caused serious ecological disruption. In general, annual species can be distinguished from perennial species based on basal vegetative characteristics. In perennial Bromus species, the dried remains of the previous years’ growth are normally present, whereas there is no previous years’ growth in the annual species. In most cases the annual taxa are generally smaller in stature and have a more delicate appearance (with some exceptions, such as some individuals of the large annual, B. diandrus), compared to the perennial taxa. Bromus sect. Bromus is characterized by 3-5-nerved first glumes, 5-7-nerved second glumes and lemmas rounded over the backs, whereas Bromus sect. Genea is characterized by 1(-3)-nerved first glumes, 3(-5)-nerved second glumes and narrow, elongate lemmas. Species of Bromus sect. Bromopsis in British Columbia are perennials with 1(-3)-nerved first glumes, 3(-5)-nerved second glumes and lemmas rounded or slightly keeled over the backs (i.e., flattened dorsiventrally). Two Bromus sect. Bromopsis species in British Columbia are introduced: meadow brome (B. riparius Rehm.), which I reported in Saarela (2008) as part of the British Columbia flora for the first time, and the highly invasive smooth brome (B. inermis Leyss.). The remaining six Bromus sect. Bromopsis species in the province are native: B. ciliatus L., B. pacificus Shear, B. porteri (J.M. Coult.) Nash, B. pumpellianus Scribn., B. richardsonii Link and B. vulgaris (Hook.) Shear.

The remainder of the Bromus taxa in British Columbia are classified inBromus sect. Ceratochloa (P. Beauv.) Griseb., a group that is widespread throughout the province and easily recognizable on the basis of its strongly laterally flattened and keeled glumes and lemmas. Species limits within Bromus sect. Ceratochloa are not clear, both in British Columbia and more broadly throughout western North America from Central America to Alaska. Multiple morphologically similar taxa in Bromus sect. Ceratochloa have been variously recognized at different ranks; in British Columbia these include B. aleutensis Trin. ex Griseb. [=B. sitchensis Bongard var. aleutensis (Trin. ex Griseb.) Hultén], B. carinatus Hook. & Arn., B. marginatus Nees ex Steud. [=B. carinatus var. marginatus (Nees ex Steud.) Barkworth & Anderton], B. polyanthus Scribn. ex Shear and B. sitchensis Bongard. Because taxon circumscriptions are not clear in Bromus section Ceratochloa, the section is not treated here.

TAXONOMIC KEY TO THE SPECIES OF BROMUS SECTIONS BROMUS, BROMOPSIS AND GENEA IN BRITISH COLUMBIA

Note: Adapted and Modified from Saarela (2008) 


1. Spikelets laterally compressed; lemmas laterally compressed and strongly keeled 
                                                          .........................Bromus sect. Ceratochloa, not treated here
1’ Spikelets not laterally compressed; lemmas flattened dorsiventrally, not strongly keeled ................................2

2. Lemmas narrow, largest lemmas generally < 2 mm wide; lemma apex bidentate, with awn-like 
   to acuminate hyaline teeth 1-5 mm long (Bromus sect. Genea)                              ................................3
2’ Lemmas broad, largest lemmas generally > 2 mm wide (except in B. vulgaris) and conspicuously 
   flattened across the back; lemma apex entire or bidentate, teeth usually not hyaline, 0-3 mm 
   long, not awn-like or acuminate                                                          ................................5

3. Lemma bodies 18-35 mm long; awns 30-50 mm long; lower glumes 12-26 mm long; upper glumes 18-35 mm long 
                                                                                    ........................ B. diandrus Roth
3’ Lemma bodies 9-22 mm long; awns < 30 mm long; lower glumes 4-14 mm long; upper glumes 7-21 mm long ......................4

4. Lemmas 13-22 mm long; awns 15-30 mm long; panicles sparse, with 1(-3) spikelets per branch; branches 
   straight, usually longer than spikelets                                                      ................B. sterilis L.
4’ Lemmas 9-13.8 mm long; awns 8-18 mm long; panicles sparse or dense, usually some branches with 
   > 3 spikelets per branch; branches sinuous, longer or shorter than spikelets.................................B. tectorum L.

5. Plants perennial, often with remnants of a previous years’ vegetative growth present; lower glumes 
   1-3-nerved; upper glumes 3-5-nerved (Bromus sect. Bromopsis)  ...........................................................6
5’ Plants annual, without remnants of a previous years’ vegetative growth present; lower glumes 
   3-5-nerved; upper glumes 5-9-nerved (Bromus sect. Bromus)     ..........................................................15

6. Plants with rhizomes; longest anthers > 4 mm long   .....................................................................7
6’ Plants without rhizomes, all anthers < 4 mm long    .....................................................................9

7. Awns (3-)4-7.1 mm long; readily decaying basal sheaths reticulate-fibrillose (i.e., thatched in 
   appearance); cilia present on palea keels only along upper 2/3 to upper half; marginal leaf blade 
   hairs robust and conspicuously widened at the base   .....................................................B. riparius Rehm.
7’ Awns 0-4 mm long; basal sheaths eventually decaying into straight fibers; cilia present on palea 
   keels along lower ¾ to entire length; leaf blades glabrous or pubescent, marginal hairs (if present)
   not robust and not conspicuously widened at the base                                     ................................8

8. Awns absent or up to 3 mm long; lemmas glabrous to variously scabrous or puberulent on lower 1/6 to 1/3
                                                                               .............................B. inermis Leyss.
8’ Awns 1-4.5(-5) mm long; lemmas with hairs 0.5-0.8 mm long along margins and midvein, or moderately
   to densely villous throughout                        ..............................................B. pumpellianus Scribn.

9. Most lower glumes 3-nerved; awns 1.5-3(-4) mm long   ........................................B. porteri (J.M. Coult.) Nash
9’ Most lower glumes 1-nerved; awns (2-)3-11 mm long    ...................................................................10

10. Auricles present and conspicuous, particularly on lower leaves; collars densely pubescent; culms
    with 9-20 nodes                                     ..............................B. latiglumis (Scribn. ex Shear) Hitchc.
10’ Auricles absent; collars glabrous or pubescent (but not densely so); culms with up to 9 nodes  ........................11

11. Glumes pubescent                                    ...................................................................12
11’ Glumes glabrous                                     ...................................................................13

12. Mature inflorescences open, 13-19 cm wide; branches broadly spreading, each with (1-)2-5 spikelets;
    awns 3-6.5(-7) mm long; ligules 2-4 mm long; leaf blades not thin and papery in herbarium material
                                                        ...................................................B. pacificus Shear
12’ Mature inflorescences narrow, 1-5 cm wide; branches erect, narrowly ascending or drooping, each
    with 1(-2) spikelets; awns (4-)6-11 mm long; ligules(2-)3-6(-7) mm long; leaf blades thin and 
    papery in herbarium material                        ............................................B. vulgaris (Hook.) Shear

13. Ligules (2-)3-6(-7) mm long; awns (4-)6-11 mm long; larger lemmas ? 2 mm wide; leaf blades thin and
    papery in herbarium material                        ............................................B. vulgaris (Hook.) Shear
13’ Ligules 0.5-3 mm long; awns 4-7(-9) mm long; larger lemmas generally > 2 mm wide; leaf blades not
    thin and papery in herbarium material               ...................................................................14

14. Lemma backs glabrous or sparsely puberulent with hairs to 0.1 mm long, margins pubescent with hairs
    0.5-1.3 mm long; upper glumes 6.5-9.5 mm long; lower glumes 5-7.5 mm long; anthers 0.9-1.6 mm long;
    basal leaf sheaths glabrous or sparsely to densely pubescent with soft and wavy hairs; upper blades
    with pilose adaxial surfaces; upper nodes usually pubescent   ..............................................B. ciliatus L.
14’ Lemma backs sparsely to densely pubescent with hairs > 0.1 mm long; upper glumes (8-)9.5-11.5(-14.5)
    mm long; lower glumes 7-9.5 mm long; anthers (1.2-)1.6-2.7(-3.4) mm long; basal leaf sheaths
    glabrous or sparsely to densely pubescent with stiff hairs; upper blades with glabrous adaxial 
    surfaces; upper nodes usually glabrous                        .......................................B. richardsonii Link

15. Lemmas appearing inflated, 3-4 mm wide; awns absent or to 1 mm long; spikelets ovate
                                                                    .........................B. briziformis Fisch. & C.A. Mey.
15’ Lemmas not appearing inflated, < 3 mm wide; awns 2-20 mm long; spikelets lanceolate to ovate-lanceolate................16

16. Lemmas with strongly protruding nerves when dry; panicles usually dense ..................................B. hordeaceus L.
16’ Lemmas smooth, without strongly protruding nerves; panicles ± open  ...................................................17

17. Awns arising 1.5-5 mm below the apex of the lemma             .........................................................18
17’ Awns arising < 1.5 mm below the apex of the lemmas            .........................................................21

18. Panicles dense and erect, some branches shorter than the spikelets; lemmas 11-20 mm long; most awns 
    >15 mm long; glumes and lemmas pilose with most hairs >= 0.9 mm long  ................................B. lanceolatus Roth
18’ Panicles lax and erect to nodding, some branches longer than the spikelets; lemmas 7-11 mm long;
    awns < 15 mm long; glumes and lemmas glabrous or pubescent with most hairs <0.9 mm long, never pilose .................19

19. Inflorescense usually racemose and appearing one-sided, the branches usually bearing a single spikelet;
    lemmas with hyaline margins 0.5-0.9 mm wide.                 .....................B. squarrosus L.  continue to 20
19’ Inflorescences usually paniculate and not appearing one-sided, at least the lower branches usually
    bearing > 1 spikelet; lemmas with hyaline margins 0.3-0.5 mm wide  ....................................B. japonicus Thunb.

20. Glumes and lemmas glabrous or scabrous                       ...............................B. squarrosus var. squarrosus
20’ Glumes and lemmas densely pubescent with hairs to 0.8 mm long  ..........................B. squarrosus var. villosus Roth

21. Lower leaf sheaths glabrous or with sparse, stiff hairs 0.5-0.6 mm long; spikelets widening
    substantially by divergence of the florets as the fruit forms, many rachillas becoming visible as
    the lemma wraps around the caryopses; caryopses U- and V-shaped in cross section ..........................B. secalinus L.
21’ Lower leaf sheaths densely pubescent with long, soft hairs to 1.2 mm long; spikelets not widening
    substantially as the fruit forms, lemmas continuing to obscure most rachillas; caryopses flat or
    crescent shaped in cross section                             ..........................................................22

22. Panicles narrow, < 2.5 cm wide; inflorescence branches < 4 cm (as measured from node to apex of
    the terminal floret); 1 spikelet per branch; most larger spikelets <22 mm long (including awns);
    lemmas 6.5-9.5 mm long                                       ..............................................B. racemosus L.
22’ Panicles broad and spreading, > 2.5 cm wide; longest inflorescence branches >4 cm (as measured
    from node to apex of the terminal floret); 1-3 spikelets per branch; larger spikelets > 22 mm 
    long (including awns); lemmas 7.5-11 mm long                 ........................................B. commutatus Schrad.
Bromus latiglumis in British Columbia and southwestern Alberta

Bromus latiglumis (Scribn. ex Shear) Hitchc. is a relatively widespread northern Parkland area taxon, distributed from south central Alberta to Nova Scotia, and the adjacent northeastern United States (e.g., Pavlick 1995; Pavlick & Anderton 2007: 209). Until recently, it was not reported for mountainous areas in southwestern Alberta and adjacent British Columbia; however, the distribution map for B. latiglumis in Flora of North America vol. 24 (Pavlick & Anderton 2007) included a dot in British Columbia near Golden, adjacent to the Banff National Park area in Alberta, and dots in extreme southwestern Alberta. Because B. latiglumis had not previously been reported for these areas, it seemed worthwhile to confirm these determinations. The southwestern Alberta dots are presumably based on three CAN specimens (or duplicate specimens deposited elsewhere) that were originally determined as B. latiglumis, but which in fact are clearly B. vulgaris. Bromus latiglumis is not known from this area. The single British Columbia dot near Golden requires confirmation, and it remains suspicious.

Specimen citations: Bromus vulgaris (Hook.) Shear [Originally identified as Bromus latiglumis (Scribn. ex Shear) Hitchc. ] Alberta: Waterton Lake, trail to Bertha Lake, 4200-6000 ft, 13 Sep 1925, M.O. Malte & W.R. Watson 2665 (CAN-38721!), 2618 (CAN-38722!); Castlemount [ranger station], 8 mi up W branch of Castle River, 4800 ft, 1 Sep 1925, M.O. Malte & W.R. Watson 2515 (CAN-38719!).

Despite the hitherto suspicion of B. latiglumis in British Columbia, a recent collection (Fig. 1) provides what appears to be the first confirmed report for British Columbia. Bromus latiglumis was recently collected by Valerie Huff (V) in the Peace River region of British Columbia (specimen originally determined by K.L. Marr [V] and confirmed here). Based on the specimen data, it seems likely that the taxon was seeded at this location for reclamation purposes.

Specimen citation: Bromus latiglumis (Scribn. ex Shear) Hitchc. British Columbia: Peace River, Mt. Wooliever, Marathon, Husky Sikanni wellsite number C-40-J, reclaimed wellsite, with seeded native grasses, some weedy species, no tree regeneration evident. Light: open, Slope: 8, Aspect: 110, BEC (Biogeoclimatic Ecological Classification): SWBmk (Moist Cool Spruce Willow Birch)57º11’46"N 123º15'01W, 1360 m, 08 Aug 2008, V. Huff & B. Haddow MAR1T2-3 (V202233!).

Bromus latiglumis is a member of Bromus sect. Bromopsis (see Introduction). It is straightforward to distinguish from all other sect. Bromopsis species in British Columbia, characterized by the following combination of characters: 9-20 nodes per culm, conspicuous auricles, and densely pubescent collars (see Taxonomic Key). A good illustration is provided in FNA vol. 24 (2007, page 210).

A second collection of Bromus riparius in British Columbia

Bromus riparius Rehm. (meadow brome) was first reported for British Columbia and characterized morphologically by Saarela (2008), based on a recent collection from the southern part of the province [Rampart Rest Area, 10 km E of Cranbrook, 23 May 2006, Saarela 417 (CAN, UBC)]. Another recent specimen (Fig. 2) collected in 2008 by Valerie Huff (V) in the Peace region appears to be the second confirmed report of the taxon for the province. Based on the specimen label information, these plants were likely seeded, which is common for B. riparius since it is widely grown as forage (see Saarela 2008). Whatever the source of the introduction, the species is clearly an element of the British Columbia flora and should be considered as such. More instances of this species should be looked for. Specimen citation: Bromus riparius Rehm. British Columbia: Peace: Mt. Wooliever, Marathon, Husky Sikanni wellsite number C-40-J, reclaimed wellsite, with seeded native grasses, some weedy species, no tree regeneration evident. Light: open, Slope: 8, Aspect: 110, BEC (Biogeoclimatic Ecological Classification): SWBmk (Moist Cool Spruce Willow Birch), 57º11'46"N 123º15'01"W, 1360 m, 08 Aug 2008, V. Huff & B. Haddow MAR1T2-15 (V202555!).

Bromus lanceolatus in British Columbia

The annual species Bromus lanceolatus Roth (lanceolate brome), native to southern Europe and northern Africa, has been introduced and collected very sporadically across the United States (Pavlick and Anderton 2007: 235). The species is cultivated as an ornamental; it is likely that this is how the species is/was introduced. In June 2007, I encountered and collected (Fig. 3) an unusual and unfamiliar Bromus species growing steadfastly in a small vacant lot directly adjacent to a small building in downtown Cumberland on Vancouver Island. The plant turned out to be B. lanceolatus, which I determined based on Pavlick and Anderton (2007) and comparison with Old World specimens at CAN. I presume these plants were cultivated somewhere nearby and escaped to this location. There is no evidence of B. lanceolatus persisting in BC, and the species should not be considered naturalized. Nevertheless, evidently it can grow in British Columbia, and since I was initially uncertain of its identity, I have included the species in the key here. Specimen citation: Bromus lanceolatus Roth British Columbia: Vancouver Island, Cumberland, Main Street, along edge of building, 49º 37’09”N 125º01’34”W, 7 June 2007, J.M. Saarela, D.M. Percy & Y.M. Chang 940 (CAN-590536!, duplicate sent to UBC).

Bromus squarrosus var. villosus: a confirmed record for Washington, U.S.A.

Saarela (2008) reported B. squarrosus var. villosus Roth for the flora of BC (and North America) based on three specimens (i.e., Kootenay, Pavlick 93-143 (V); Hells Gate, Saarela et al. 736 (CAN, UBC); Waneta, Lomer 6268 (UBC, V) . Frank Lomer (personal communication, March 2009) has confirmed the presence of this taxon in northeastern Washington, based on a UBC specimen. Specimen citation: Bromus squarrosus var. villosus Roth U.S.A.: Washington: Lincoln Co., Wilbur, low places, black soils on scablands, 47°45'24"N 118°42'23"W, 18 June 1947, V.C. Brink 47-9-1 (UBC-V20405), determined by F.L. Lomer, 2009.

Summary of taxonomic changes for British Columbia Bromus in Saarela (2008) and here compared with Illustrated Flora of British Columbia (IFBC; Douglas et al. 2001)

British Columbia Bromus specimen data not published previously

In Saarela (2008) I cited only a fraction of the Bromus material housed in the herbarium at the Royal British Columbia Museum (V). Georeferenced latitude and longitude data, when not present on specimen labels, were kindly provided by John Pinder-Moss (V). I have confirmed all of the determinations, and present these previously unpublished data here in full in Appendix 1: http://bomi.ou.edu/ben/415/

Acknowledgements

I am grateful to Barney L. Lipscomb (Editor, JBRIT) for allowing reproduction of parts of the published manuscript; John Pinder-Moss (V) for help with herbarium requests, for providing specimen label data, and for hospitality during a visit to the herbarium at the Royal British Columbia Museum (RBCM); Micheline Bouchard and Jennifer Doubt (both CAN) for their ongoing help with herbarium loan requests; and Kelly Sendall (RBCM) for clarifying the RBCM policy on publishing herbarium record data. Frank Lomer (UBC) and Luc Brouillet (MT) provided important information.

References

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Taxonomy of Bromus (Poaceae : Pooideae : Bromeae) sections Bromopsis, Bromus, and Genea in British Columbia, Canada. Journal of the Botanical Research Institute of Texas 2(1): 323-372.
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