4. RHUS L.
Trees or shrubs, with pithy branchlets, fleshy roots, and milky sometimes caustic or watery juice. Leaves unequally pinnate, or rarely simple. Flowers mostly diœcious, rarely polygamous, white or greenish white, in more or less compound axillary or terminal panicles, the staminate and pistillate usually produced on separate plants; calyx-lobes united at base only, generally persistent; disk surrounding the base of the free ovary, coherent with the base of the calyx; petals longer than the calyx-lobes, inserted under the margin of the disk, opposite its lobes, deciduous; stamens 5, inserted on the margin of the disk alternate with the petals; filaments longer than the anthers; ovary ovoid or subglobose, sessile; styles 3, terminal, free or slightly connate at base, rising from the centre of the ovary. Fruit usually globose, smooth or covered with hairs; outer coat thin and dry, more or less resinous; stone crustaceous or bony. Seed ovoid or reniform, commonly transverse; cotyledons foliaceous, generally transverse; radicle long, uncinate, laterally accumbent.
Rhus is widely distributed, with more than one hundred species, in the extra-tropical regions of the northern and southern hemispheres. In North America the genus is widely and generally distributed from Canada to southern Mexico and from the shores of the Atlantic to those of the Pacific Ocean, with sixteen or seventeen species within the territory of the United States. Of these, four obtain the habit of small trees. The acrid poisonous juice of Rhus vernicifera DC., of China, furnishes the black varnish used in China and Japan in the manufacture of lacquer, and other species are valued for the tannin contained in their leaves or for the wax obtained from their fruit.
The name of the genus is from Ῥοῦς, the classical name of the European Sumach.
CONSPECTUS OF NORTH AMERICAN ARBORESCENT SPECIES.
Flowers in terminal thyrsoid panicles; fruit globular, clothed with acrid hairs; leaves unequally pinnate, deciduous; Sumachs. Branches and leaf-stalks densely velvety hairy; leaflets 11—31, pale on the lower surface; fruit covered with long hairs; buds inclosed in the enlarged base of the petioles; juice milky.1. [R. typhina] (A, C). Branches and leaf-stalks pubescent; rachis winged; leaflets 9—21, green on the lower surface; fruit pilose; buds not inclosed by the petioles; juice watery.2. [R. copallina] (A, C). Flowers in axillary slender panicles; fruit glabrous, white; leaves unequally pinnate, deciduous; leaflets 7—13.3. [R. vernix] (A, C). Flowers in short compact terminal panicled racemes; fruit pubescent; leaves ovate, entire or serrate, simple or rarely trifoliolate, persistent.4. [R. integrifolia] (G).
1. [Rhus typhina] L. Staghorn Sumach.
Rhus hirta Sudw.
Leaves 16′—24′ long, with a stout petiole usually red on the upper side and covered with soft pale hairs, enlarged at base and surrounding and inclosing the bud developed in its axil, and 11—31 oblong often falcate rather remotely and sharply serrate or rarely laciniate long-pointed nearly sessile or short-stalked leaflets rounded or slightly heart-shaped at base, covered above like the petiole and young shoots when they first appear with red caducous hairs, bright yellow-green until half grown, and at maturity dark green and rather opaque on the upper surface, pale or often nearly white on the lower surface, glabrous with the exception of the short fine hairs on the under side of the stout midrib, and primary veins forked near the margins, opposite, or the lower leaflets slightly alternate, those of the 3 or 4 middle pairs considerably longer than those at the ends of the leaf, 2′—5′ long, and 1′—1½′ wide; turning in the autumn before falling bright scarlet with shades of crimson, purple, and orange. Flowers opening gradually and in succession in early summer, the pistillate a week or ten days later than the staminate, on slender pedicels from the axils of small acute pubescent bracts, in dense panicles, with a pubescent stem and branchlets, and acuminate bracts ½′ to nearly 2′ long and deciduous with the opening of the flowers; panicle of the staminate flowers 8′—12′ long and 5′—6′ broad, with wide-spreading branches and nearly one third larger than the more compact panicle of the pistillate plant; calyx-lobes acute, covered on the outer surface with long slender hairs, much shorter than the petals in the staminate flower, and almost as long in the pistillate flower; petals of the staminate flower yellow-green sometimes tinged with red, strap-shaped, rounded at apex, becoming reflexed above the middle at maturity; petals of the pistillate flower green, narrow and acuminate, with a thickened and slightly hooded apex, remaining erect; disk bright red and conspicuous; stamens slightly exserted, with slender filaments and large bright orange-colored anthers; ovary ovoid, pubescent, the 3 short styles slightly connate at base, with large capitate stigmas, in the staminate flower glabrous, much smaller, unusually rudimentary. Fruit fully grown and colored in August and ripening late in the autumn in dense panicles 6′—8′ long and 2′—3′ wide, depressed-globose, with a thin outer covering clothed with long acrid crimson hairs and a small pale brown bony stone; seed slightly reniform, orange-brown.
A tree, occasionally 35°—40° high, with copious white viscid juice turning black on exposure, a slender often slightly inclining trunk occasionally 12′—14′ in diameter, stout upright often contorted branches forming a low flat open head, and thick branchlets covered with long soft brown hairs gathered also in tufts in the axils of the leaflets, becoming glabrous after their third or fourth year, and in their second season marked by large narrow leaf-scars and by small orange-colored lenticels enlarging vertically and persistent for several years; more frequently a tall shrub, spreading by underground shoots into broad thickets. Winter-buds conic, thickly coated with long silky pale brown hairs, about ¼′ long. Bark of the trunk thin, dark brown, generally smooth, and occasionally separating into small square scales. Wood light, brittle, soft, coarse-grained, orange-colored, streaked with green, with thick nearly white sapwood. From the young shoots pipes are made for drawing the sap of the Sugar Maple. The bark, especially that of the roots, and the leaves are rich in tannin. A form with narrow deeply divided leaflets (f. dissecta Rehdr.) occasionally occurs.
Distribution. Usually on uplands in good soil, or less commonly on sterile gravelly banks and on the borders of streams and swamps, New Brunswick and through the valley of the St. Lawrence River to southern Ontario and westward to eastern North Dakota and eastern and northeastern Iowa, and southward through the northern states and along the Appalachian Mountains to northern Georgia and Mississippi; more abundant on the Atlantic seaboard than in the region west of the Appalachian Mountains.
Occasionally cultivated as an ornamental plant in the United States, and very commonly in central and northern Europe.
× Rhus hybrida Rehdr. a hybrid of R. typhina and R. glabra L. has been found in Massachusetts.
2. [Rhus copallina] L. Sumach.
Leaves 6′—8′ long, with a slender pubescent petiole and rachis more or less broadly wing-margined between the leaflets, the wings increasing in width toward the apex of the leaf, and 9—21 oblong or ovate-lanceolate leaflets entire or remotely serrate above the middle, sharp-pointed or rarely emarginate at apex, acute or obtuse and often unequal at base, those of the lower pairs short-petiolulate and smaller than those above the middle of the leaf, the others sessile with the exception of the terminal leaflet sometimes contracted into a long winged stalk, when they unfold dark green and slightly puberulous above, especially along the midrib, and covered below with fine silvery white pubescence, at maturity subcoriaceous, dark green and lustrous above, pale and pubescent below, 1½′—2½′ long and about ¾′ wide, with slightly thickened revolute margins, a prominent midrib and primary veins; turning in the autumn before falling dark rich maroon color on the upper surface. Flowers appearing from June in the south to August in the north, those of the staminate plant opening in succession during nearly a month and continuing to unfold long after the petals of the pistillate plant have fallen, on stout pubescent pedicels ⅛′—¼′ long, in short compact pubescent panicles, the lower branches from the axils of the upper leaves, 4′—6′ long, 3′—4′ broad, and usually smaller on the female than on the male plant, their bracts and bractlets ovate or oblong, densely cinereo-pilose, deciduous before the expansion of the flowers; calyx puberulous on the outer surface, with ovate acute lobes one third as long as the ovate greenish yellow petals rounded at apex, becoming reflexed above the middle; disk red and conspicuous; stamens somewhat longer than the petals, with slender filaments and large orange-colored anthers, in the pistillate flower much shorter than the petals, with minute rudimentary anthers; ovary ovoid, pubescent, glabrous, much smaller in the staminate flower. Fruit ripening in five or six weeks and borne in stout compact often nodding pubescent clusters sometimes persistent on the branches until the beginning of the following summer, ⅛′ across, slightly obovoid, more or less flattened, with a thin bright red coat covered with short fine glandular hairs, and a smooth bony orange-brown stone; seed reniform, smooth, orange-colored, with a broad funicle.
A tree, 25°—30° high, with colorless watery juice, a short stout trunk 8′—10′ in diameter, erect spreading branches, and branchlets at first dark green tinged with red and more or less densely clothed with short fine or sometimes ferrugineous pubescence, appearing slightly zigzag at the end of their first season from the swellings formed by the prominent leaf-scars, and then pale reddish brown, slightly puberulous and marked by conspicuous dark-colored lenticels; or at the north usually a low shrub rarely more than 4°—5° tall. Winter-buds minute, nearly globose, and covered with dark rusty brown tomentum. Bark of the trunk ⅓′—½′ thick, light brown tinged with red, and marked by large elevated dark red-brown circular excrescences, and separating into large thin papery scales. Wood light, soft, coarse-grained, light brown streaked with green and often tinged with red, with thin lighter colored sapwood of 4 or 5 layers of annual growth. The leaves are rich in tannin and are gathered in large quantities and ground for curing leather and for dyeing.
Distribution. Dry hillsides and ridges; widely and generally distributed from northern New England to southern Florida, and to southeastern Iowa, southeastern Nebraska, eastern Kansas and the valley of the San Antonio River, Texas; in Cuba; in the United States arborescent only southward; at the north rarely more than a few feet high and spreading by underground stems on gravelly sterile soil into broad thickets; varying considerably in the size and form of the leaflets. The most distinct and probably the most constant of these varieties is var. lanceolata A. Gray, a small tree growing on the prairies of eastern Texas to the valley of the Rio Grande and to southeastern New Mexico, often forming thickets on river bluffs or on the banks of small streams, and distinguished by its narrow acute often falcate leaflets and by its larger inflorescence and fruit. A tree sometimes 25°—30° high, with a trunk occasionally 8′ in diameter, covered by dark gray bark marked by lenticular excrescences. The flowers appear in July and August and the dull red or sometimes green fruit ripens in early autumn and falls before the beginning of winter.
Occasionally cultivated as an ornamental plant in the eastern United States, and in western and northern Europe.
3. [Rhus vernix] L. Poison Dogwood. Poison Sumach.
Leaves 7′—14′ long, with a slender usually light red or red and green petiole, and 7—13 obovate-oblong entire leaflets slightly unequal at base and narrowed at the acute or rounded apex, bright orange color and coated, especially on the margins and under surface, with fine pubescence when they unfold, soon becoming glabrous, and at maturity 3′—4′ long, 1½′—2′ wide, dark green and lustrous above, pale below, with a prominent midrib scarlet above, primary veins forked near the margins, conspicuous reticulate veinlets, and revolute margins; turning early in the autumn before falling to brilliant shades of scarlet or orange and scarlet. Flowers about ⅛′ long, appearing in early summer on slender pubescent pedicels bibracteolate near the middle, in long narrow axillary pubescent panicles crowded near the end of the branches, with acute pubescent early deciduous bracts and bractlets; calyx-lobes acute, one third the length of the yellow-green acute petals erect and slightly reflexed toward the apex; stamens nearly twice as long as the petals, with slender filaments and large orange-colored anthers, in the fertile flower not more than half the length of the petals, with small rudimentary anthers; ovary ovoid-globose, with short thick spreading styles terminating in large capitate stigmas. Fruit ripening in September and often persistent on the branches until the following spring, in long graceful racemes, ovoid, acute, often flattened and slightly gibbous, tipped with the dark remnants of the styles, glabrous, striate, ivory-white or white tinged with yellow, very lustrous, and about ½′ long; stone conspicuously grooved, the wall thin, membranaceous; seed pale yellow.
A tree, with acrid poisonous juice turning black on exposure, occasionally 25° high, with a trunk 5′—6′ in diameter, slender rather pendulous branches forming a narrow round-topped head, and slender glabrous branchlets reddish brown and covered with minute orange-colored lenticels when they first appear, orange-brown at the end of their first season, becoming light gray and marked by large elevated conspicuous leaf-scars; more often a shrub, with several slender clustered stems. Winter-buds acute and covered with dark purple scales puberulous on the back, and ciliate on the margins with short pale hairs, the terminal ⅛′—¾′ long and two or three times larger than the axillary buds. Bark of the trunk thin, light gray, smooth or sometimes slightly striate. Wood light, soft, coarse-grained, light yellow streaked with brown, with lighter colored sapwood.
Distribution. Wet swamps often inundated during a portion of the year; northern New England to northern Florida and southern Alabama, and westward to Ontario and southeastern Minnesota, western Louisiana and the valley of the Neches River (San Augustine County) eastern Texas; common and one of the most dangerous plants of the North American flora. An infusion of the young branches and leaves is employed in homœopathic practice, and the juice can be used as a black lustrous durable varnish.
4. [Rhus integrifolia] B. & H. Mahogany.
Leaves simple or very rarely 3-foliolate, persistent, acute or rounded at apex, with thickened revolute, or spinosely toothed margins (var. serrata Engler), puberulous when young, and at maturity 1½′—3′ long, 1′—1½′ wide, thick and coriaceous, dark yellow-green above, paler below, and glabrous with the exception of the stout petiole, broad thick midrib, and prominent reticulate veins. Flowers appearing from February to April, ¼′ in diameter when expanded, on short stout pedicels, with 2—4 broad-ovate pointed persistent scarious ciliate pubescent bractlets, in short dense racemes forming hoary-pubescent terminal panicles 1′—3′ in length; sepals rose-colored, orbicular, concave, ciliate on the margins, rather less than half the length of the rounded ciliate reflexed rose-colored petals; stamens as long as the petals, with slender filaments and pale anthers, minute and rudimentary in the pistillate flower; ovary broad-ovoid, pubescent, with 3 short thick connate styles and very large 3-lobed capitate stigmas, rudimentary in the staminate flower. Fruit ½′ long, ovoid, flattened, more or less gibbous, thick, dark red, densely pubescent; stone kidney-shaped, smooth, light chestnut-brown, with thick walls; seed flattened, pale, with a broad dark-colored funicle covering its side.
A tree, rarely 30° high, with a short stout trunk 2°—3° in diameter, numerous spreading branches, and stout branchlets covered when they first appear with thick pale pubescence disappearing in their second and third years, and bright reddish brown and marked by numerous small elevated lenticels; or usually a small often almost prostrate shrub. Winter-buds small, obtuse, covered with a thick coat of pale tomentum. Bark of the trunk ¼′—½′ thick, bright reddish brown, exfoliating in large plate-like scales. Wood hard, heavy, bright clear red, with thin pale sapwood of 8—10 layers of annual growth; valued and largely used as fuel. The fruit is occasionally employed in the preparation of a cooling beverage.
Distribution. Sandy sterile soil along sea beaches, and bluffs in the immediate vicinity of the ocean; neighborhood of Santa Barbara, Santa Barbara County, California, to the shores of Magdalena Bay, Lower California, and on the Santa Barbara and Cedros islands; on the mainland usually shrubby, forming close impenetrable thickets; in more sheltered situations and on the islands becoming arborescent; probably of its largest size on the shores of Todos Santos Bay, Lower California.