Flora of North America species comparison

Arctostaphylos patula is abundant and widespread in western North America as a dominant in montane chaparral, pine forest gaps, and high-elevation arid-steppe and canyon-land environments. Populations throughout western North America are characterized by twigs and inflorescence parts covered with relatively short hairs tipped with golden glands. In the central to northern Sierra Nevada, mixed with the widespread form are individuals that are eglandular and have a cover of relatively short, whitish hairs on the stems and inflorescences. Similarly, throughout most of its range, A. patula is nonsprouting after fire, and in areas characterized by winter snow cover it layers and creates broad, low mounds. In much of California, it typically sprouts after fires from obscure and flattened burls, forming circles of erect sprouts.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Arctostaphylos uva-ursi exhibits great variation in indument associated with the young twigs. Most of this variation has historically been separated into subspecies, except that a recent analysis of the group suggested environmentally-based variation in these characters (T. J. Rosatti 1987b). This is the most widely distributed of all Arctostaphylos species and is the only one found outside of North America. Two ploidy levels are common, and populations sometimes contain both diploids and tetraploids. More work on this widespread species will likely elucidate its variation in morphology and ploidy. Infraspecific taxa may well be recognized once these patterns are further assessed.

A form with striking deep red to purple autumnal corollas (often blooming also in spring with normal-colored corollas) occurs on Cape Cod and Nantucket Island, Massachusetts.

Most populations lack burls and are killed by fire; throughout the range in North America are occasional populations or individuals that have small, sometimes epicormic burls. This has been noted in California, parts of Canada, and New York. With more observations this distribution may become clearer.

A form with somewhat puberulent and larger leaves has been described as Arctostaphylos ×media Greene. It occurs along the northern California coast and in Oregon and Washington. It is assumed to be a hybrid between A. uva-ursi and A. columbiana. Similarly, in the Rocky Mountains in areas with both A. uva-ursi and A. patula, hybrids have been called A. coloradensis Rollins.

(Discussion copyrighted by Flora of North America; reprinted with permission.)