J.G. in San Francisco took today's Botany Photo of the Day at Regional Parks Botanic Garden in Berkeley, California. Thanks once again to J.G. for sharing his invariably wonderful photos in our Flickr pool. (Original Image). Steve Coughlin wrote this entry.

Rosaceae is a fairly large family that consists of between 100 and 160 genera, and between 3000 and 4000 species. The family's many fruits adhere roughly to four basic structural patterns, by which botanists often—though not always—divide the family into the four subfamilies of Rosoideae, Spiraeoideae, Maloideae, and Amygdaloideae. These subfamilies variously produce apples, pears, peaches, strawberries, raspberries, blackberries, and several other edible fruits and nuts as well. Of course, members of Rosaceae are also cultivated as the showy, fragrant, and sought-after ornamentals of bouquet, lapel, and poetic renown.

A genus of about 10 deciduous, shrubby species, Physocarpus is primarily native to North America, though a few species hail from northeastern Asia. Physocarpus is distinguished in part by the way in which its bark peels away from its stem in flaky layers. The genus's common name originally derived from the (mistaken) belief that there were 9 of these strata, and its scientific name comes from the Greek for 'bladder fruit'. Species range from 1 to 4 metres in height, and don palmate, serrated leaves along with small, five-petaled white flowers.

Physocarpus capitatus, a native of North America's western coast, grows to a height of 4 metres and to a spread of 1 metre. The species name, capitatus, refers to the plant's dense, head-like clusters of flowers and fruits. The plant flowers in late-spring to early-summer, and thrives in a combination of slightly acidic soil and ample sun, particularly when sited in the moist soils of mountain slopes, lake shores, and river margins. Though moisture is integral to the plant's success, Physocarpus capitatus is nevertheless quite drought-resistant and is hardy to zone 5.

In today's photo, P. capitatus conjures thoughts of kettle corn kernels pressed tightly together, sweating and ready to pop. While this pre-bloomed sight is itself something to savour, the species—which serves as a common garden ornamental in California—has achieved particular distinction for its appearance after its blooms have fallen, when a bronze-coloured shield of dry seed husks emerges as if to protect the remaining plant from the harsh summer sun.