Claire Fadul wrote today’s entry:
Dale Hameister (Dale Hameister@Flickr) of Redlands, CA provided us with this vibrant photograph of Eriastrum densifolium subsp. sanctorum (taken in early June last year) via the Botany Photo of the Day Flickr Pool. Much appreciated Dale!
Eriastrum densifolium, or giant woollystar, (this particular sub-species is the rarer Santa Ana woollystar) is a common sight in the drier places of California and can usually be found in sandy soils and seasonally dry washes. California is the centre of present-day biodiversity for the Polemoniaceae, or phlox family. Nowadays, the family is mostly found in the New World (approx. 25 genera containing 400 species in North and South America vs. only 3 genera in the Old World). However, what few fossil records exist (Polemoniaceae tend not to grow in places conducive to fossil formation) indicate the presence of Polemoniaceae pollen from Eocene Spain and Pliocene Europe (as well as Miocene California and mid-Eocene Utah).
Eriastrum densifolium subsp. sanctorum is both endemic and endangered in southern California, where it inhabits alluvial washes around the Santa Ana River floodplain. The Seven Oaks Dam is a major threat to the long-term survival of Eriastrum densifolium subsp. sanctorum, as it reduces crucial sediment and new sand deposits the plant relies on for reproduction. Fortunately, a number of people, including professors and students at Cal State Fullerton, are conducting long-term research with an eye to conservation of this rare taxon.
Blooming in the summertime, Eriastrum densifolium subsp. sanctorum has particular pollinators which also share the same habitat requirements of sandy washes. Depending on the location, Burk et al. in a 1989 field study found digger bees, anise swallowtail butterfly, and various hummingbirds to be common pollinators, as well as the “giant flower-loving fly”, Raphiomidas actoni subsp. actoni. Some of these species may be mutually dependent on the Santa Ana woollystar, so it is important to continue conservation efforts for the endangered woollystar in order to preserve all constituents of this fragile ecosystem.