Cooper’s popcornflower is a species of flowering plant in the borage family, referred to scientifically as Plagiobothrys collinus var. ursinus.
Native to California, Arizona, and the Mexican state of Baja California, it can be found in many types of habitats, including coastal sage scrub, chaparral, valley grassland, and open areas of oak woodland. In San Bernardino County it occurs generally at elevations of between 3,400 feet and 7,400 feet. An endicot angiosperm, Plagiobothrys collinus is an annual herb growing in turf-like patches or tufts. It boasts a spreading or erect stem that is usually 3.9 inches-to-15.7 inches in length, with hairs that are generally coarse.
The leaves along the stem are tapered at the base and broadly rounded at the end and two-fifths of an inch to an inch-and-a-half long, the lower ones oppositely arranged and the upper ones alternate. The herbage is coated in fine and rough hairs.
The inflorescence of the Cooper’s popcornflower is a long, widely spaced series of tiny flowers, each with a five-lobed white corolla no more than 7 millimeters wide, sometimes as small as one millimeter. The white corollas exist in tight coiled clusters referred to by botanists as scorpioid cymes. The bloom period is February through May. The fruit is a minute nutlet with angular cross-ribs visible in magnification. The flower clusters of plagiobothrys collonus approximate from a distance the appearance of popped grains of corn. Botanists refer to this as an exploded endosperm. The resemblance to popcorn is particularly pronounced when the plant is spread out and low growing.
The plant does well in sandy or gravelly granite-based soils and open conifer forests.
Plagiobothrys species have been known to accumulate free nitrates in quantities capable of causing death or distress in cattle that feed upon them. A rich purple dye or stain is contained in the root and stems of the plagiobothrys species in general.
From Vascular Plants of Upper Newport Bay, Wayne P. Armstrong’s Desert Naturalist, Wikipedia, https://plants.usda.gov and http://ucjeps.berkeley.edu/eflora/