JARS v60n3 - The Ericaceae of the Pacific Northwest, Part II

The Ericaceae of the Pacific Northwest, Part II
Wilbur L. Bluhm
Salem, Oregon

Part I of the series, which began in the Spring 2006 issue of the Journal, led with a general discussion of the family Ericaceae, an overview of the Northwest Ericaceae and descriptions of two NW ericaceous species.

Part II continues with plant description of NW species in the genus Arctostaphylos . The genus Arctostaphylos manzanita , consists of about 60 species in North and Central America and Eurasia, and 11 in Pacific Northwest. Of the 60, about 55 grow in California. A number of species include varieties or subspecies. Quite a few interspecific hybrids have been found, and the number seems to grow.

All manzanitas have similar identifying characteristics. All are shrubs or small trees. All have leathery evergreen leaves, not usually more than a couple inches long and as wide, varying from one species to another in size, shape, color, and hairiness. Virtually all have bark similar to the cinnamon or reddish brown under-bark of Arbutus menziesii (see part I) and similar exfoliating bark on larger stems.

Flowers of manzanitas are either urn-shaped or spheric and like those of Arbutus in color and size. Fruits that follow are a pulpy, berry-like drupe with 2 to 10 stones, and orangish in color.

Manzanitas are often beautiful plants, tempting introduction to the garden. With but a few exceptions, they tend to be difficult to grow, susceptible to poorly drained soils and root diseases, and have exacting growing requirements.

Those whose range is from southern Oregon southward grow under very warm and dry conditions during summer. Duplicating these conditions in the garden, to extent possible, is to their liking.

A. canescens , Hoary, or Downy, Manzanita , grows to 6 feet or more. Twigs are densely short-soft-hairy to white tomentose (woolly). Leaves are 1½ to 2 inches long and to an inch wide, and canescent, that is, grayish or whitish in color with short, fine hairs. The inflorescence is sometimes glandular. Its range includes southwest Oregon and northern California.

Two hybrids are known in Oregon, A. canescens X A. nevadensis [x parvifolia], and A. canescens X A. patula .

A. x cineria , Waldo, or Ashy, Manzanita , is found in southwest Oregon to northern California. It apparently is a hybrid of A. canescens X A. viscida . Its characteristics are intermediate of the two species. Waldo Manzanita is sometimes given full species status.

A. columbiana , Hairy, or Bristly, Manzanita , grows from southwest British Columbia to northern California, west of Cascade Mountains. It matures from 6 to 30 feet tall, and can be tree-like. It's common on rocky slopes and in or near coniferous forests, from near sea level to 2500 to 3000 feet. Twigs are densely tomentose with long, white bristles. Leaves are 1½ to 2⅓ inches long and about an inch wide, finely tomentose, dark green, dull, sparsely glandular-bristly, becoming glabrous with age. Flower stem is finely glandular-bristly.

Crosses of A. columbiana with A. uva-ursi are called A. x media . Another known hybrid is A. columbiana X A. nevadensis .

A. glandulosa ssp glandulosa , Eastwood's Manzanita, grows from southwest Oregon southward to just north of San Francisco, California, on slopes, ridges, chaparral, and in forests between 900 and 6000 feet. A shrub, it matures at 3 to 8 feet. A definitive feature of Eastwood's Manzanita is its large burl, wide and flat-topped, at the base of the plant near ground level.

Twigs are finely glandular-bristly or finely tomentose. Leaves are bright green, sometimes slightly glaucous (bluish or grayish), glandular-hairy, papillate (pitted), and scabrous (rough) or sparsely hairy. Leaves are ¾ to 1¾ inches long by ⅓ to an inch wide, and may or may not be toothed.

A. hispidula , Howell's, or Gasquet, Manzanita, is a shrub 3 to 6 feet tall with finely glandular-bristly twigs. Leaves are ½ to more than an inch long, from ¼ to nearly ¾ inch wide. They may or may not be toothed, dark green, upper and lower surfaces alike, dull to somewhat shiny, finely glandular-bristly, pitted and scabrous. Fruits are about ¼ inch in diameter, whitish tan, becoming glaucous.

Howell's Manzanita is an uncommon plant in southwest Oregon into northern California at 900 to 2,000 feet on open rocky serpentine soils or sandstone, often near or in open forests.

A. klamathensis , Klamath Manzanita, is a mat or mound-like plant less than a foot and half tall. Twigs are finely glandular-bristly. Leaves are also small, ⅓ to 1⅓ inches long, ¼ to an inch wide, with or without teeth. Upper and lower leaf surfaces are alike, more or less glaucous, dull, papillate and scabrous, with a sparsely but finely glandular-bristly mid vein.

Klamath Manzanita grows on rocky outcrops, slopes, and in subalpine forest, at 5,000 to 6,500 feet at Scott Mountain Divide and Slate Mountain in northern California.

A. x media , Intermediate Manzanita, is reported in Oregon on the southern coast and in northern Willamette Valley, and possibly in northern California. It is an A. columbiana and A. uva-ursi hybrid . Intermediate Manzanita is in the nursery trade, and so is its cultivar, 'Wood's Red'. 'Grandiflora' and '#14' may still be available.

A. nevadensis , Pinemat Manzanita, is one of the more common manzanitas in Pacific Northwest. It grows from northern California into Washington on rocky soils, near coniferous forests, at 3000 to near 10,000 feet, highest in the southern extension of its range.

Pinemat Manzanita is spreading and low growing, mat to mounding, less than 2 feet high. Leaves are ⅓ to an inch or so long and ⅓ to over a half inch wide. Both leaf surfaces are bright green, shiny, sometimes fine hairy, becoming glabrous and smooth. A point at leaf tip helps to distinguishes this species from A. uva-ursi , not including other differences.

Pinemat Manzanita has more ornamental potential than most manzanitas, making a good groundcover with optimum growing conditions. The cultivars 'Cascade', 'Chipeta', and 'Ponchito' are in the nursery trade.

Several hybrids have been identified: A. nevadensis X A. patula ; A. nevadensis X A. glandulosa (X knightii , X parvifolia ); A. nevadensis X A. columbiana .

A. nortensis , Del Norte Manzanita, is an uncommon species in Del Norte County, California, just south of Oregon border. This shrub, 3 to 6 feet tall, is found on rocky slopes, sometimes on serpentine, and chaparral, often in or near coniferous forests. Twigs are tomentose, sometimes bristly. Leaves are ¾ to 1½ inch long, ⅓ to ¾ inch wide. Both leaf surfaces are alike, finely white tomentose, becoming dark green, dull, glabrous, and smooth.

A. patula , Green Leaf, or Snowbrush, Manzanita, has one of the broader ranges of manzanitas, from Baja California, through the Sierra Mountains into southern Washington, east to Montana and Colorado, in open coniferous forests. This 3 to 6 foot shrub forms circular clones. Its lower, more or less decumbent, stems often strike root in the ground.

Twigs have glistening golden glands or are finely glandular-bristly. Leaves are 1 to 2½ inches long and ½ to more than 1½ inches wide, bright green, shiny, glabrous, and smooth. Both surfaces are alike. Its leaves make Green Leaf Manzanita one of the more easily identified manzanita species.

Among listed hybrids are A. nevadensis X A. patula , and A. patula X A. uva-ursi .

A. uva-ursi , Kinnikinnick, Bearberry, is easily the best known manzanita because of its wide range and widespread use as a groundcover in United States and Canada. Its range may be the greatest of any manzanita, from northern California to Alaska, into Rocky Mountains, central and northeast United States, eastern Canada, and Eurasia. It is one of finest groundcovers known, especially for dry banks, and with good soil drainage, a necessity. Many cultivars are being grown and are generally available.

Kinnikinnick is a trailing plant seldom taller than 6 to 10 inches. Leaves are up to an inch long and ⅔ inch wide, shiny, dark green on upper surface and lighter green on lower, mostly glabrous, and smooth. The rounded end of the leaf can be used to help distinguish this species from A. nevadensis , which has a point on the leaf end. The ¼ inch urn-shaped flowers, followed by red ¼ inch berries, add to its aesthetic qualities.

Kinnikinnick in its range grows on rocky outcrops, slopes, sandy soils, chaparral, can be in or near coniferous forests, generally below 300 feet elevation, although it is up to 5,000 feet or more in the Cascade Mountains and probably higher in the Wallowa Mountains of northeast Oregon. Another of its higher places is in central Sierra Nevada Mountains of California where it is said to grow at 8,000 to 10,000 feet.

Known hybrids include A. patula X A. uva-ursi , and A. columbiana X A. uvaursi .

A. viscida , Whiteleaf, or White Leaved, Manzanita, matures at 3 to 15 or more feet. It can be found in northern California and southwest Oregon on rocky slopes, and in woodland, chaparral, and coniferous forests at 500 to 6,000 feet.

Twigs are glabrous or densely fine-glandular-bristly. Leaves are ¾ to 2 inches long and nearly as wide, sometimes toothed, sometimes with hairs on leaf edge (ciliate). They are white glaucous, dull, glabrous, or more or less sparsely finely glandular-bristly, papillate, and scabrous. The ¼ to ⅓ inch spheric berries are red brown, and glabrous or finely glandular-bristly and sticky.

Wilbur Bluhm is a member of the ARS Willamette Chapter and of the Willamette Valley Chapter, Native Plant Socity of Oregon. He is retired from Oregon State University Extension Service where he was an Extension horticulturist, staff chairman of the office at Salem and now Professor Emeritus.