Selected Plants from Rock’s Expeditions

South Central China and Tibet: Hotspot of Diversity

Selected Plants from Rock’s Expeditions Growing at the Arnold Arboretum

View a map of the locations of these plants.


Buddleja syn. Buddleia
Buddleia alternifolia
Alternate-leaf butterfly bush
Family: Loganiaceae
Hardiness zones: 5-9

Buddleia alternifolia

Buddleia alternifolia

This buddleia is a large deciduous shrub with long, slender, arching branches that bear flowers on the previous year’s growth. Flowering begins in early summer; the dense, rounded clusters are fragrant and lilac-colored. The leaves are alternate, slender, and gray-green in color. With an annual growth of more than 18 inches, this shrub can reach its mature, rounded form with a height and spread of 15 feet relatively quickly.


Cotoneaster acutifolius Turczaninow
Peking cotoneaster
Family: Rosaceae
Hardiness zones: 4-7

Cotoneaster acutifolius

This cotoneaster is a dense, upright, and spreading deciduous shrub with arching branches. Its pinkish-white flowers are borne in summer and are followed by brilliant red, or occasionally black, fruit. The leaves are round and a dark green during the growing season, but turn orange-red in the fall.
Its annual growth rate is from 12 to 18 inches, and its rounded form reaches 6 to 8 feet in height and spread.

Cotoneaster horizontalis Decaisne
Rock or rockspray cotoneaster
Family: Rosaceae
Hardiness zones: 5-7

Cotoneaster horizontalis

Cotoneaster horizontalis

This species’ flat, layered, herringbone-branching habit makes it one of the most widely grown
of all prostrate cotoneasters. Deciduous in New England, it is semi-evergreen farther south.
By mid June small, pink flowers appear singly or in pairs. In fall, the foliage turns from a
lustrous, dark green to bright red, as do the fruits. It will reach a height of
2 to 5 feet and a spread that exceeds 10 feet.

Cotoneaster taoensis G. Klotz
Creeping cotoneaster
Family: Rosaceae
Hardiness zones: 4b-7

Cotoneaster taoensis

A prostrate, deciduous cotoneaster, this species has short, rigid branches and a dense, spreading habit. Its small, pink-tinged, white flowers appear singly or in pairs in late spring and are followed by spherical, bright-red fruit. Although not as vigorous as C. horizontalis, it is a good groundcover with a height of one foot and an annual growth rate of 12 to 18 inches.


Euonymus phellomana Loesener
Family: Celastraceae
Hardiness zone: 5

Euonymus phellomanus

Euonymus phellomanus

Although this medium-to-large euonymus has attractive cork-like, winged stems and excellent autumn color, unfortunately it is seldom, if ever, grown for its ornamental qualities.


Picea asperata Masters
Dragon spruce
Family: Pinaceae
Hardiness zones: 6-8

Picea asperata

Picea asperata

A slow growing, columnar conifer with a spread that can reach 20 feet, this spruce has horizontal branches that can become pendulous with age. Its stiff, prickly needles are thick, curved and a bluish green and become a darker green as they remain on the tree for as long as seven years. Reaching 75 to 80 feet in height, the dragon spruce has scaly, dark, purplish brown bark and light brown, 3 to 5-inch long cones.