Treesearch

Saltcedar (Tamarix chinensis (Lour.)) and smallflower tamarisk (T. parviflora DC.) hybridize in the Southwest (Baum 1967; Horton and Campbell 1974) and are deciduous, pentamerous tamarisks that are both commonly referred to as saltcedar. Saltcedar is a native of Eurasia that has naturalized in the southwestern United States within the last century. It was introduced into the eastern United States in the 1820s (Horton 1964) and was once widely cultivated as an ornamental, chiefly because of its showy flowers and fine, graceful foliage.

Gorse is a leafless, spined shrub introduced from western Europe. In its homeland, it grows 1 to 2 m tall and is primarily a nonaggressive invader of disturbed areas that is recognized as useful for wildlife protection, soil stabilization, and revegetation. It has also been cultivated as an ornamental and as forage for livestock, which feed on the soft, new growing shoots. Its major use in the past, however, was for hedgerows to contain livestock before barbed wire (Jobson and Thomas 1964). As a useful plant, European settlers carried gorse to many parts of the world where it quickly...

There are about 30 species of yucca native to North America and the West Indies. Although most of these long-lived, evergreen plants grow in the arid southwestern United States and on Mexican tablelands, yuccas are found up to 2,400 m in elevation in the mountains of Colorado (Arnott 1962; Webber 1953). Four western species are considered here (table 1). Great Plains yucca is a small acaulescent shrub 1 to 2 m tall, with narrow, swordshaped, spine-tipped, upright leaves 6 to 12 mm wide. Soaptree yucca is a medium to large caulescent shrub up to 9 m tall, with similar but wider (5 cm) and...

Siltbush is an autumn-deciduous shrub or sub-shrub ranging from 0.1 to 0.8 m in height (Goodrich and Neese 1986). Stems of the current year are thornless and erect or ascending, branching from a persistent, woody base. Leaves are gray-scurfy and entire to lobed. Overwintering leaf buds are prominent, axillary, and globose (Welsh and others 1987).

Holodiscus is a taxonomically complex genus including about 6 species of western North America and northern South America (Hitchcock and others 1961; Ley 1943). The 2 generally recognized North American species (table 1) - creambush ocean-spray and gland ocean-spray - are deciduous, multistemmed shrubs with simple, alternate, deciduous, toothed to shallowly lobed, exstipulate leaves.

Two woodybased non-rhizomatous sub-shrub species of kochias are found in the western United States. The widely distributed native, gray molly, and its introduced and closely related counterpart (Blackwell and others 1978), forage kochia, are found in salt-desert, sagebrush, pinyon-juniper, and dry mountain brush communities (table 1). Erect to steeply ascending annual stems growing from a woody base and long-lived prostrate branches attain heights of 5 to 50 cm for gray molly (Welch and others 1987) and 10 to 100 cm for forage kochia (Baylan 1972).

The larches - Larix P. Mill. - of the world are usually grouped into 10 species that are widely distributed over much of the mountainous, cooler regions of the Northern Hemisphere (Hora 1981; Krussmann 1985; Ostenfeld and Larsen 1930; Rehder 1940; Schmidt 1995). Some species dominate at the northern limits of boreal forests and others occur above subalpine forests (Gower and Richards 1990). Seven species are included (table 1) - the others, Master larch (L. mastersiana Rehd. & Wils.), Chinese larch (L. potaninii Batal.), and Himalayan larch (L. griffithiana (Carr.)) - are rarely planted in...

The mulberry genus - Morus - comprises about 12 species of deciduous trees and shrubs native to temperate and subtropical regions of Asia, Europe, and North America (Rehder 1956). Seeds of 2 native species and 2 naturalized species are described here (table 1). White (sometimes called "Russian") mulberry was introduced to the United States by Mennonites from Russia in 1875. The United States Prairie States Forestry Project planted an average of over 1 million trees of this species annually from 1937 through 1942 for windbreaks in the Great Plains from Nebraska to northern Texas (Read and...

The genus Penstemon comprises about 230 species of perennial herbs and subshrubs, most of which are found in western North America. Although most of the species are herbaceous, there are many more subshrubby species than are treated here. Several shrubby species from California that were formerly included in the genus Penstemon have been transferred to the closely related genus Keckiella Straw. In the previous edition of the Seed Manual, Hylton (1974) treated these species under the name Penstemon.

Amur corktree - Phellodendron amurense Rupr. - is native to northern China, Manchuria, Korea, and Japan. This small to medium deciduous tree - 25 to 50 feet tall - has been cultivated in the Far East and eastern Europe. It was introduced into the United States around 1865, and its thick, corky bark and massive, irregular branches have made it of special interest for landscape and environmental plantings in the northern and western United States (Blackburn 1952; Everett 1964; Hoag 1965; Lewis 1957). In tests in Kansas, however, the tree did not perform well and was not recommended for...