This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Small trees, shrubs, or climbing vines, with 3-foliolate or pinnate leaves, poisonous to the touch, and axillary panicles of small, greenish or white, polygamous flowers unfolding after the leaves. Calyx 5-cleft; petals and stamens 5; ovary I-ovuled; style terminal. Drupes glabrous or sparingly pubescent when young, the stone striate. [Greek, poison-tree.]
About 20 species, natives of North America and Asia. Type species: Rhus Toxicodendron L.
Leaflets 7-11, glabrous.
Leaflets 3 only.
Glabrate, or somewhat pubescent; leaflets thin, entire or sinuate; fruit not papillose.
Densely pubescent; leaflets firm in texture, deeply 3-7-lobed; fruit papillose.
1. Toxicodendron VÚrnix (L.) Kuntze. Poison or Swamp Sumac. Poison Elder. Fie 2781.
Rhus Vernix L. Sp. Pl. 265. 1753.
Toxicodendron pinnatum Mill. Gard. Dict. Ed. 8, no. 4. 1768.
Rhus venenata DC. Prodr. 2: 68. 1825.
Toxicodendron Vernix Kuntze, Rev. Gen. PL 153. 1891.
A shrub or small tree, with maximum height of 250 and trunk diameter of 6'. Leaves petioled, pinnate, 6'-15' long, glabrous or somewhat puberulent; leaflets 7-13, thin, obovate, oval, or the lowest ovate, 2-4' long, 1'-1 1/2' wide, green both sides, entire, short-acuminate at the apex, narrowed or rounded at the base, short-stalked; rachis terete; flowers green, about 1" broad, in loose axillary panicles 3'-8' long; drupe globose-oblong, 2" in diameter, gray, glabrous.
In swamps. Maine to Vermont, southern Ontario, Florida, Minnesota, Missouri and Louisiana. Very poisonous. Wood soft, yellowish brown; weight per cubic foot 27 lbs. June. Poison ash or tree. Swamp or poison dogwood. Poison-wood.
2. Toxicodendron radicans (L.) Kuntze. Poison, Climbing or Three-leaved
Rhus radicans L. Sp. PI. 266. 1753.
Rhus Toxicodendron of American authors, in part, not L. Toxicodendron vulgare Mill. Gard. Dict. Ed.
8, no. 1. 1768. Rhus microcarpa Steud. Nomencl. 689. 1821. T. radicans Kuntze, Rev. Gen. 153. 1891.
A woody vine, climbing by numerous aerial rootlets, or erect and bushy, the stem sometimes 3'-4' in diameter. Leaves petioled, 3-foliolate, glabrate or somewhat pubescent, especially beneath; leaflets ovate or rhombic, 1'-4' long, entire or sparingly dentate or sinuate, acute or short-acuminate at the apex, the lateral sessile or short-stalked, inequilateral, the terminal one stalked, rounded or narrowed at the base; flowers green, 1 1/2" broad, in loose axillary panicles, 1-3' long; fruit similar to that of the preceding, 1 1/2"-2 1/2" in diameter, glabrous, or sparingly pubescent.
Thickets and along fences, etc., often ascending high trees, Nova Scotia to British Columbia, Florida, Arkansas, Texas and Mexico. Bermuda; Bahamas. Very poisonous. Consists of many races, differing in habit, shape of leaflets and pubescence. Trailing or climbing sumac. Mercury. Black mercury-vine. Markry. Mark-weed. Picry. May-June.