186 AMERICAN MIDLAND NATURALIST 
branches either erect or ascending, or when leaving the stem 
from beneath winding themselves around it in an upward direction, 
2-20 cm. long, striate, lenticillate and more or less tuberculate 
by the marks of leaf-attachment of earlier years, the growth of 
the season represented by the herbaceous top or tops, which are 
1-2 cm. long. These herbaceous tops send forth the leaves and 
racemes and become, after the autumnal shedding of the leaves, 
woody and permanently naked. It is also a not unusual occur- 
rence, that the top remains sterile, and. that the seasonal growth 
originates in one or more secondary branches. Leaves pinnately 
3-foliolate, generally 1-3 from the same top, their petioles 3-10 
cm. long. Leaflets 3-7 cm. long, 2.5—-5 cm. wide, broadly ovate, 
acuminate, thick, shining, pilose on the veins of the lower side, 
margins ciliate, entire or on the upper half wavy or sinuately tooth- 
ed, petioles of the end leaflet 8-15 mm. long and of the lateral ones 
2-5 mm. long. Flowers in small, short and narrow axillary panicles 
on short peduncles. Fruits whitish, shining, globular, 4-5 mm. in 
diameter, remaining after the dropping of the leaves. 
This species has a trailing ally, T. vulgare Mill. (Rhus radicans 
L., in part), which is often a vine climbing by aerial rootlets, has 
a stem often 7—10 cm. in diameter, and a depressed-globose fruit, 
always distinctly broader than high. 
This small-leaved species prefers a bare, deeply gravelly 
prairie-soil, and was collected by the writer on July 13, 1899, in 
Sand Hills, McHenry County. Although he always has been 
handling plants of both species here described “‘fearlessly”’ and 
“with absolute impunity,’ more susceptible individuals are prob- 
ably not altogether immune, when they come in contact with 
this “poison oak.” Still during a medical practice of 23 
years in this state he did never meet with a case of true Poison 
Oak dermatitis, and only a few imaginary cases. 
Toxicodendron fothergilloides sp. nov. 
Caudex horizontalis, subterraneus, ramis erectis supra solum 
crescentibus, quorum quisque plantae singulari similis est, 25 
em. altus, parte infima e tribus subterranea. Qui rami ubi folia 
priora inserta erant subtus protuberantiis magnis vestiti et apicibus 
summis circiter 2 cm. longis exceptis ubi partes herbaceae tem- 
pestivae confertae sunt lignei. Ex contrario progressus tempes- 
tivus interdum in ramo quodam secundo oritur. Folia pinnatim 
