Treesearch

The mock oranges - Philadelphus spp. - have been placed in several families: Saxifragaceae (Harrington 1954), Hydrangeaceae (Hitchcock and others 1961), and more recently, the Philadelphaceae (Hickman 1993). Hydrangeaceae, however, is the most widely accepted placement (Cronquist and others 1997; USDA NRCS 2001). There are about 50 to 65 species of mock orange, occurring primarily in temperate and subtropical areas of the Northern Hemisphere. Four or five species are native to the United States. Two of these - Lewis mock orange (Philadelphus lewisii Pursh) and littleleaf mock orange (P....

The bitterbrush genus - Purshia - as presently circumscribed comprises 8 species of decumbent to arborescent shrubs of interior western North America. Three are common in the United States (table 1). The type species - antelope bitterbrush - has an essentially northern distribution, whereas cliffrose has an essentially southern distribution, and desert bitterbrush occurs in parts of the geographic area where the other 2 species have overlapping distributions. Cliffrose, along with the 5 Mexican species of the genus, has been traditionally referred to the genus Cowania D. Don. Cliffrose...

The genus Cytisus comprises about 80 species native to Eurasia and North Africa. Many are cultivated as ornamentals, and several of these have become more or less naturalized in the United States, especially in California (Munz and Keck 1959). Scotch broom - C. scoparius (L.) Link - was planted extensively for erosion control during the first half of the century (Gill and Pogge 1974) but is now considered a serious invasive weed throughout the range of its introduction in North America, Australia, and New Zealand (Bossard 1991). It has become the dominant species on several hundred...

The genus Ephedra - known in much of North America as Mormontea - comprises about 40 shrubby species that are found throughout the arid and semiarid regions of the Northern Hemisphere. Ephedras are gymnosperms that are characterized by their greatly reduced, bractlike leaves and their evergreen, broomlike photosynthetic stems. They are common plants in the semiarid region of western North America (table 1) and are often locally codominant with creosotebush (Larrea tridentata (Sesse & Moc. ex DC.) Coville), blackbrush (Coleogyne ramosissima Torr.), shadscale saltbush (Atriplex confertifolia...

The North American genus Eriogonum - wild-buckwheat, also buckwheatbrush - is made up of about 200 species of annual and perennial herbs and shrubs, most of which are found in the West. About half are woody, at least at the base. The habit of the woody species may be either (a) truly shrubby, (b) subshrubby, with annual renewal of upper shoots, or (c) pulvinate (mat-forming), with the woody shoots condensed into an above-ground caudex. The usually evergreen leaves are borne alternately and may be predominantly basal or borne along the stems. There may be whorls of leaves on the flowering...

The genus Fallugia contains a single species - Apache-plume, F. paradoxa (D. Don) Endl. ex Torr. - found throughout the southwestern United States and northern Mexico. It occurs mostly on coarse soils on benches and especially along washes and canyons in both warm and cool desert shrub communities and up into the pinyon-juniper vegetation type. It is a sprawling, much-branched shrub from 1 to 2.5 m in height that can root-sprout to produce extensive patches (Shaw and Monsen 1983). It has white to straw-colored, flaking or scaly bark and fascicles of small wedge-shaped leaves that are...

The genus Fremontodendron is endemic to California and adjacent areas of Arizona and Baja California. It includes 2 common and 1 rare species (table 1) (Kelman 1991). Fremontias are shrubs or small trees with evergreen leaves that are alternate, entire to lobed, and covered with characteristic stellate hairs. They are components of chaparral vegetation and are able to resprout abundantly after fire. The resprouts are valuable forage for deer and domestic livestock (Nord 1974). Fremontias are handsome plants that are used extensively in California for roadside and residential landscaping...

The genus Garrya - silktassel - consists of 14 New World species ranging from the Pacific Northwest to Panama (Dahling 1978). Only those in the United States and Mexico are considered here. Garrya is a highland genus occurring in chaparral and coniferous forests above lowland deserts, in semiarid regions, or in coastal or near-coastal conditions. Species may vary in size from low shrubs to trees (table 1). First discovered by David Douglas in the Pacific Northwest in 1826, Garrya was named in honor of Nicholas Garry, the first secretary of the Hudson Bay Company (Dahling 1978). Alternativel...

Ginkgo is a monotypic genus native to China, the sole survivor of the ancient family of Ginkgoaceae (Bailey 1923; Dallimore and Jackson 1948; Seward and Gowan 1900). Geologic records indicate that ginkgos have grown on Earth for 150 million years (AGINFO 1994). This tall (

The genus Grayia Hook. & Arn., named for the American botanist Asa Gray, contains a single species - spiny hopsage (table 1). Plants are erect to rounded, summer-deciduous shrubs 0.3 to 1.2 (1.5) m tall. Branches are divergent and thorn-tipped, with whitish gray to brownish bark that exfoliates in long strips. Leaves are gray-green, alternate, entire, and fleshy, sometimes turning bright red before abscising. Pubescence of young twigs and leaves consists of simple or stellate hairs. Prominent globose, gray-green overwintering leaf buds develop prior to summer leaf fall.