**Bromus madritensis L. (Poaceae)**

**Foxtail Chess**

**Description**. Annuals, 1.5-4.5 dm tall, erect, stems erect, glabrous
to short-soft-hairy. Leaves alternate; ligules 1-3 mm long, lacerate;
auricles absent; sheaths glabrous to sofi-pubescent; blades linear,
flat, 1.5-4 mm wide, glabrous to sofi-puberulent. Inflorescence an open
to dense terminal panicle, 4-8 cm long. Spikelets 20-30 mm long,
slightly compressed, composed of 3-8 florets, the glumes linear to
narrowly lanceolate, the lower one 5-10 mm long, 1-nerved, the upper one
8-13 mm long, 3-nerved; lemmas 12-17 mm long, lanceolate, 3-5-nerved,
the back keeled to rounded, the apex with a terminal awn 12-20 mm long
and two lateral teeth 4-5 mm long. In California, flowering from March
to June. (Hitchcock 1944, Holmgren and Holmgren 1977, Munz 1959, Pavlik
1995, Smith 1980, Wilken and Painter 1993).

**Note**: *Bromus madritensis* comprises two morphological races, *B.
madritensis* ssp. *madritensis* and ssp. *rubens*. Subspecies
*madritensis* has glabrous to slightly pubescent sheaths and stems, and
the inflorescences are somewhat open and oblqng to ovoid. Subspecies
*rubens* has pubescent sheaths and stems, and the inflorescence is dense
and ovoid. Subspecies *rubens* tends to occur in drier habitats than
ssp. *madritensis*. Esnault (1984) described pafferns of geographic
variation in *Bromus madritensis* in Mediterranean Europe and northern
Africa, providing evidence for intergradation between the two subspecies
in its native range. In contrast, Pavlik (1995) treated the two races as
distinct species.

*Bromus madritensis* is closely related to *B. tectorum* L. and *B.
diandrus*, both weedy, arid-land species naturalized throughout much of
western North America. *Bromus diandrus* , like *B*. *madritensis*, has
a lower glume with 1 vein, but differs by having the lower glume 10-20
mm long and the lemma awns 30-60 mm long. The former differs from true
*B*. *rigidus* by several traits, including longer and spreading to
pendent spikelets (Gill and Carstairs 1988, Pavlik 1995, Smith 1980).
*Bromus hordeaceus* is characterized by 3-veined lower glumes and lemma
awns 4-9 mm long and includes plants previously referred to as *B.
mollis* and *B. molliformis* (Smith 1980).

**Geographic distribution**. A native of southern Europe, *Bromus
madritensis* has been introduced and naturalized in southern Africa and
western North America from British Columbia south to Mexico, generally
west of the Great Basin. (Arnold and de Wet 1993, Gibbs Russell et al.
1955, Hitchcock 1944, Holmgren and Holmgren 1977, Tselev 1984). It (only
as ssp. *rubens*) has been reported as a waif in scattered localities
east of the Rocky Mountains (Fernald 1950, Gleason and Cronquist 1991).

Both subspecies of *Bromus madritensis* were first reported from
California in the late 19th century (i.e., ssp. *madritensis* by Watson
(1880); ssp. *rubens* by Parish 1920). *Bromus madritensis* ssp.
*rubens* has been reported from all northern California Islands (Junak
et al. 1997). Subsp. *madritensis* is apparently restricted only to
Santa Cruz Island. The species is widely distributed throughout most
California counties, but ssp. *madritensis* occurrs primarily west of
the Sierra Nevada (Anonymous 1998).

*Bromus diandrus* (previously known as *B. rigidus*), a native of
Mediterranean and southwestern Europe, is widespread in western North
America, South America, Australia, southern Africa, Hawaii, and Japan
(Arnold and de Wet 1993, Chapman 1991, Gibbs Russell et al. 1955, Gill
and Carstairs 1988, Hitchcock 1944, Holmgren and Holmgren 1977, Kon and
Blacklow 1989, 1990, Koyama 1987, Wagner et al. 1990). *Bromus diandrus*
was first reported from San Francisco by Watson (1880), but it had
apparently become widely established throughout California before the
end of the 19th century (Parish 1920, Burtt Davy 1902, Robbins 1940).

*Bromus hordeaceus* (previously known in California as *B. mollis*), a
native of Europe, is widespread throughout much of western North
America, Hawaii, South America, and Asia (Arnow 1987, Holmgren and
Holmgren 1977, Koyama 1987, Wagner et al. 1990). *Bromus* *hordeaceus*
may have become widely established no later than the end of the 19th
century (Burtt Davy 1902, Parish 1920, Robbins 1940).

**Reproductive and vegetative biology**. Like most grasses, *Bromus*
species are wind-pollinated wind (Proctor et al. 1996). The reproductive
biology of *Bromus diandrus*, *B*. *hordeaceus*, and *B. madritensis*
apparently has not been studied in detail. However, both *Bromus*
*diandrus* and *B. madritensis* are self-compatible and have a mixed
mating system that is skewed toward self-pollination (Brown and Allard
1981, Kon and Blacklow 1990). Seeds of both *B*. *diandrus* and *B.
madritensis* germinate readily, but their recruitment and local
distribution differ slightly in relation to soil microtopography (Harper
et al. 1965).

In California, seed production in both *B. diandrus* and *B. hordeaceus*
is inversely related to soil moisture and cool growing conditions, but
reproductive capacity and seed production under drought conditions
remains relatively high (Ewing and Menke 1983, Gleichsner and Appleby
l996, Gordon and Rice 1992). A certain proportion of *Bromus diandrus*
seeds remain dormant under cultivated conditions, especially with
shallow tillage and can persist for several years (Cheam 1986, Harradine
1986). *Bromus diandrus* had higher densities in sunny rather than
shaded conditions, and persisted under shade, relative to *Bromus
hordeaceus*, in *Quercus agrifolia* woodland (Maranon and Bartolome
1993). In these oak savannas, *Bromus hordeaceus* was almost entirely
restricted to open, sunny sites between tree canopies.

**Ecological distribution**. Introduced species of bromes tend to occur
in disturbed sites, roadsides, fallow fields, and grazed pastures
(Arnow, 1987, Munz 1959, Wilken and Painter 1993), and (with *Avena*
spp.) have become an important component of the annual grasslands and
savannas in California (Heady 1956, 1990). *Bromus madritensis* tends to
be a lesser component of the California annual grassland relative to *B.
hordeaceus* and *B. diandrus* (Bentley and Talbot 1948, Heady 1956,
1958, 1990, Talbot et al. 1939). Both *Bromus diandrus* and *B.
hordeaceus* tend to occur over a broader range of soil types and
rainfall regimes than *B*. *madritensis* (Heady 1990, Janes 1969, McCown
and Williams 1968). *Bromus diandrus* tends to occur more frequently on
sites with higher annual rainfall than those supporting either *B.
madritensis* or *B. hordeaceus* (Janes 1969). Bentley and Fenner (1958),
Heady (1956), Parsons and Stohlgren (1989), and Talbot et al. (1939)
reported that fire had little effect on species composition of annual
grasslands dominated by *Bromus*, apparently because residual seed banks
were unaffected by fire.

*Bromus diandrus* has been reported as a common understory annual in
closed cone pine forests, oak woodlands, and coastal prairies, depending
on precipitation and substrate (Elliott and Wehausen 1974, Holland 1974,
Maranon and Bartolome 1993, Philbrick and Haller 1990, Vogl et al. 1990,
Peñalosa, J. 1963). *Bromus diandrus* also negatively affects
establishment of blue oak (*Q. douglasii*) seedlings, because early
germination, high densities, and deep root penetration reduce water
availability (Gordon et al al. 1989, Gordon and Rice 1992, 1993).
Similar mechanisms in Australian wheat fields have been reported by Gill
et al. (1987). Under experimental conditions, *Bromus diandrus* became
established as a result of early rains and moist winters (Robinson and
Quinn 1988, Robinson et al. 1995). It may also alter soil-water
conditions to favor its persistence (Holmes and Rice 1996).

**Weed status**. Bromus madritensis is not considered a noxious weed in
agricultural or horticultural practice, at least at a global level (not
listed by Holm et al. 1977) nor is it listed for the United States in
Lorenzi and Jeffery (1987). However, subspecies *rubens* is considered a
noxious weed in California deserts by the State Dept. of Food and
Agriculture (Anonymous 1996).

Neither *Bromus diandrus* nor *B. hordeaceus* are considered noxious
weeds by Holm et al. (1977), Lorenzi and Jeffery (1987) or the State
Dept. of Food and Agriculture (Anonymous 1996).

**Microbial and insect pathogens**. No literature was found that
reported either microbial or insect pathogens of *Bromus madritensis*,
*B. diandrus*, or *B. hordeaceus*.

**Herbicide control**. Triazinone herbicides, dimethazone, and
metribuzin have been used to control *B*. *diandrus* (Dial and Thill
1988, Garcia et al. 1994). Resistance to metribuzin in *B. diandrus* has
been reported by Gill and Bowran (1990). No other literature pertinent
to herbicide control was found.

**Other control methods**. Heenan et al. (1990) evaluated varying
patterns of tillage and crop rotation in controlling *Bromus diandrus*.
Rotation of wheat with lupin crops reduced infestation by *Bromus
diandrus* when combined with occasional herbicide treatment, light
tilling, and retention of stubble (Cheam et al. 1992).

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