Bromus grossus was once a widespread companion of traditional winter
cereals such as
spelt and
rye across the
calcareous farmlands of central-western Europe. Historical
herbarium records and floristic surveys compiled for Belgium show that, during the late nineteenth century, the grass was recorded from more than seventy 4 × 4 km squares, chiefly on the limestone
plateaux flanking the
Meuse valley. By the late twentieth century, however, it survived in barely a dozen Belgian localities, and comparable declines have been documented in France, Switzerland and southern Germany. The pattern is closely tied to agricultural intensification: deep
ploughing, systematic
herbicide use, mineral
fertilisers and the near disappearance of on-farm spelt seed stocks have eliminated the shallow-tilled, nutrient-poor field margins where
B. grossus completes its annual life cycle. Ecologically, the species
germinates in autumn alongside the crop,
overwinters as a small tuft and flowers in early summer. Its tough axis prevents the ripe from shattering, so the seed was historically harvested and re-sown with the cereal, an inadvertent "farming partnership" now broken by modern
seed cleaning. Where it still persists—in a handful of
Walloon,
Bavarian and Swiss fields—the grass is usually restricted to lightly fertilised spelt strips or uncultivated
headlands that escape spraying. Conservationists therefore regard
B. grossus as a
flagship for arable-weed
biodiversity. Current measures focus on agri-environment schemes that maintain winter cereals three years in five, ban synthetic inputs along a two-metre field border and encourage farmers to retain small amounts of local spelt seed deliberately "contaminated" with the brome.
Botanical gardens also backstop wild populations by storing seed at low temperature, a feasible strategy because the species shows little
dormancy loss in cold, dry conditions. Without such combined
in situ and ex-situ actions, the grass is expected to vanish from open countryside within a few decades. ==References==