2 Family Burseraceae

2. FAMILY BURSERACEAE The Gumbo Limbo (Bursera Simaruba, Sarg.), sole arbores cent species of the single genus of its family represented in the United States, is a tree very commonly met with in southern Florida. It is the only native tree that sheds its leaves in the autumn. This habit it shares with the ubiquitous China tree of the Southern garden. Winter reveals a round-headed tree, with stout horizontal limbs, trunk and branches covered with reddish brown bark, which peels off in thin flakes of irregular sizes. The soft wood easily falls a prey to disease and insect injury; a tree 5o feet high often falls to pieces from these causes. The species reminds one of willows in its ability to sprout from the stump and from fragments of any size set in the ground. Fence posts are soon clothed in verdant foliage if cut from a gumbo limbo tree and driven at once. Screens and hedges are made by sticking twigs into the ground.

Gumbo limbo is a popular street and lawn tree; its ash-like leaves, very new and fresh, make a grateful summer shade.

The flowers appear with the leaves in early spring. They are borne in lateral elongated clusters; the individual blossoms are imperfect and inconspicuous in size and colour, the two sorts on separate trees. The fruit looks like a green berry as it develops, but it breaks in ripening in a dry, 3-valved pod, each cell of which contains two triangular red seeds.

Beside its horticultural uses, the tree is valuable for a resinous gum which exudes from wounds in the trunk. This is made into varnish, and was formerly used in the treatment of gout. The Florida "cracker" makes tea of the leaves when "store tea" is not at hand.

Small trees or shrubs with stout, pithy branchlets, and viscid, usually milky, juice. Leaves alternate, usually pinnately compound. Flowers minute, greenish, polygamo-dioecious, in compound panicles. Fruit a small, dry drupe.

KeY TO SPECIES A. Leaves pinnate, of 9 to 31 leaflets, deciduous.

B. Fruit whitish, in loose, drooping, axillary panicles.

(R. Vernix) POISON SUMACH BB. Fruit red, in erect, compact terminal panicles.

C. Branches, fruit clusters and leaf stalks densely hairy; leaflets II to 31; juice milky.

(R. hirta) STAGHORN SUMACH CC. Branches, fruit clusters and leaf stalks pubescent; rachis winged; leaflets 9 to z1; juice watery.

(R. eopallrna) DWARF SUMACH AA. Leaves simple, evergreen.

(R. integrz7olia) WESTERN SUMACH The sumachs form a temperate zone genus of a great tropical family, comprising fifty genera and 40o species. There are about

120 species of the genus Rhus; they are most abundant in South Africa. Sixteen species are found in North America, only four of which are ever trees. Of these, none compare in economic importance with the sumach cultivated in southern Europe, whose leaves contain 25 to 3o per cent. of tannic acid, and are regularly gathered and dried, and used in the tanning of fine leathers. The pistachio-nut tree, from Asia Minor, now cultivated in southern California, is a relative of our roadside sumachs, as is also the turpentine tree of southern Europe. They belong to the genus Pistacia, and are both commercially important.

The Japanese lacquer tree (Rhus vernicifera, DC.) exceeds all other species in value; its sap is the black varnish used in making lacquered wares. Each year about 13o,000 gallons of this valuable substance are gathered in Japan and China. Each little tree yields but a few ounces, and is killed by the draining process. The acrid juice of R. Vernix, our poison sumach, is milky and turns black on exposure to the air, forming a substance very much like the lacquer varnish.

Staghorn Sumach, Hairy Sumach (Rhus hirta, Sudw.)— A low, flat-topped tree, 3o to 35 feet high, with branches stout, erect, forked many times, and densely velvety. Bark smooth, brown; hair on branches soft, long, and changing from pink to green the first year; later, dark, short; shed the third or fourth year. Wood light, coarse, soft, brittle, but satiny when polished, green streaked with orange. Buds pointed, in summer covered by leaf base, in winter almost buried. Leaves pinnate; leaflets ti to 31, narrow, pointed, serrate, dark green above, pale to white beneath; velvety; autumn colours scarlet, orange and purple. Flowers, June, inconspicuous, greenish, in dense, conical, hairy clusters, the two sorts on separate trees. Fruit tiny, globular acid drupes, densely hairy, red, in large, compact panicles, which remain through the winter. Preferred habitat, uplands and gravelly banks. Distribution, southern Canada to Winnipeg; south to Georgia and Mississippi. Uses : Planted as an orna mental for its foliage and fruit. Wood used for walking sticks, and for inlaying boxes, tabourettes and other fancy -articles. Twigs used as pipes to draw maple sap from the trees.