1 mm long. Plants break-apart rapidly when desiccated. Disturbed coastal and urban sites. Grows best on well-drained soils. Plants are damaged by frosts a few degrees below freezing and are killed by colder temperatures.
Escaped populations are uncommon.
North Coast, San Francisco Bay region. The biology of capeweed is poorly understood. Seeds disperse with human activities, animals, and probably wind. Seedlings tolerate dry conditions. In pastures, mowing and close grazing can increase the ratio of capeweed to desirable vegetation.