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Bromus diandrus

Scientific Name: Bromus diandrus
Common Name: Great Brome

Line Drawing:

Morphological Description:
Tall hairy grass that can grow to be 1-3ft (30 – 90 cm) tall
Thin, sharp seeds
Backwards facing hairs, “rip-gut” grasses
Rough and dry, with purple steak along the veins

Habitat & Basic Biology (life history, dispersal abilities):
Germinates during autumn and winter while blooming in the spring and summer
The “rip-gut” leaves allow easy catching to fur, tissue, or clothing
Can be found in rangeland, noncropland, and amongst cultivated crops
Seeds germinate quickly following after-ripening

Functional traits (photosynthetic rates, phenology, etc.):
Annual grass
Flowers within 100 days of vernalization
Flowering inhibited when exposed for several days after vernalization
Relatively stable at various humidity levels

Distribution (geographic range):

Native to the Mediteranian area
First reported as a weed in in Spain (Del Monte)
Invaded region include other areas of Europe, North America, North American, Australia, North Korea, Japan, and several other countries

Control Methods:
Selective controls on different herbicides, though have been unsuccessful for the most part
Depletion of seed bank and prevention of growth

Evolution (of traits in novel range):
Vernalization as a possible adaptation to dry summers and drought by allowing a build up of seed mass

Performance of invader in CA (interactions with species native to S. CA):
Highly competitive and sheds a large quantity of seeds

Natural enemies:
Grazing animals, though has low palapability

List of References:
Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals, including the Consortium of Calif. Herbaria. [web application]. 2014. Berkeley, California: The Calflora Database [a non-profit organization]. Available:   (Accessed: May 05, 2014).

Stromberg, Mark. “Bromus Diandrus.” Common Non-Native Grasses. Hastings Reserve, n.d. Web. 06 June 2014. Hastings is a biological field station at the University of California, and provide information on invasive species for free tot he public.