Part 16

The Tree of Heaven (Ailanthus glandulosa, Desf.), introduced from Asia, has been extensively planted along streets and on lawns from which it has escaped in many places.

ANACARDIACEAE—THE CASHEW FAMILY

The Cashew or Sumach family is mainly tropical comprising about 50 genera with 500 species of trees, shrubs and woody vines. Its members are not valuable as wood producers but in many cases they have commercial importance on account of their acrid, milky, or resinous juice, used in medicine, tanning, and the manufacture of varnishes and resins, and on account of their attractive appearance when planted as ornaments. The genus Rhus, (pp. 169, 171, 173) is the only one native to Northeastern America. There are 120 known species of Rhus, about 16 of which are found in North America and 6 in West Virginia. Besides those described in this bulletin the following shrubby species grow wild in the State: Smooth Sumach (Rhus glabra, L.), Poison Ivy (Rhus Toxicodendron, L.) and Fragrant Sumach (Rhus canadensis, Marsh.)

The Smoke Tree (Rhus Cotinus, L.), an introduced tree, is planted on lawns.

AQUIFOLIACEAE—THE HOLLY FAMILY

The Holly family with 5 genera and nearly 300 species is distributed in temperate and tropical regions of both hemispheres. Ilex, (pp. 175, 177) which is represented in West Virginia by 4 species of small trees and shrubs, is the only genus of this family which is important in number of species or is widely distributed. Our hollies, not described herein, are Winterberry (Ilex verticillata, (L.) Gray), a low shrub common in high swamps; and a rare shrubby species with long-stalked fruits (Ilex longipes Chapm.) recently collected in Randolph County. Nemopanthus mucronata, (L.) Trel., also a member of this family, is a common shrub growing at high altitudes in this State.

ACERACEAE—THE MAPLE FAMILY

This family includes only 2 genera, one of which (Dipternia) contains a single Chinese species. The genus Acer comprises about 70 species distributed principally in the northern hemisphere. There are 13 species native to the United States, 6 of which are found in West Virginia.

The maples not only produce much valuable wood but are used more extensively than any other group for ornamental purposes. The principal exotic species are Norway Maple (Acer platanoides, L.), and Sycamore Maple (Acer Pseudo-Platanus, L.).

The following key will be of use in distinguishing the species:

KEY TO THE SPECIES OF ACER

a. Leaves simple.

b. Leaf sinuses acute at base.

Leaf-lobes long and narrow, leaves silvery white beneath; fruit in pairs, each key 1-2 inches long, falling in May =A. saccharinum, p. 187.=

Leaf-lobes short and broad, leaves white-downy beneath, 3-lobed; fruit small, several, persistent till fall, in long drooping clusters; a small tree or shrub =A. spicatum, p. 181.=

Leaves whitish and nearly glabrous beneath, 3-5 lobed, lobes broad and short; fruit in small clusters, falling in early summer =A. rubrum, p. 189.=

b. Leaf sinuses rounded at base, leaves 3-lobed, finely and evenly toothed; fruit several in drooping racemes; a small tree or shrub with striped bark =A. pennsylvanicum, p. 179.=

Leaves usually 5-lobed (or 3-lobed in variety nigrum, p. 185), the lobes sparingly wavy-toothed; fruit in small clusters, persisting until fall; a large tree =A. saccharum, p. 183.=

a. Leaves compound; twigs greenish; fruit in long drooping racemes =A. negundo, p. 191.=

SAPINDACEAE—THE SOAPBERRY FAMILY

This family embraces 100 genera and about 1000 species, chiefly tropical in the Old World. Six genera of trees occur in North America. The genus Aesculus, (pp. 193, 195) comprises 14 species, 10 of which are found in America and 2 in West Virginia. No other genus of this family is represented in the flora of the State. The Horse Chestnut (Aesculus Hippocastanum, L.) is a common introduced species.

TILIACEAE—THE LINDEN FAMILY

The Linden family with about 35 genera and over 300 species is chiefly tropical, having more representatives in the southern than in the northern hemisphere. Of the 3 North American genera only one (Tilia) is arborescent. Of the 8 species of Tilia (pp. 197, 199) found in North America 2 are native to West Virginia. The European Linden (Tilia Europea, L.) is occasionally planted.

ARALIACEAE—THE GINSENG FAMILY

This family having about 50 genera with over 400 species is chiefly tropical, though widely distributed in other parts of the world. The genus Aralia (page 201) contains the only tree species in North America. This is common in West Virginia.

CORNACEAE—THE DOGWOOD FAMILY

The Dogwood family, with 15 genera, is widely distributed in temperate regions. Cornus (pp. 203, 205) and Nyssa (page 207) are the only genera having tree representatives in North America. Of the 40 known species of Cornus 15 are native to North America and 7 to West Virginia. The shrubby species are listed on page 234. Nyssa comprises 7 known species, 5 of which are found in North America and 1 in this State.

ERICACEAE—THE HEATH FAMILY