3. Plants glabrous, smooth and shining, without stinging bristles; achene longer 

 than the calyx 4. Pilea 



1. Laportea Gaudich. Wood-nettle 



About 25 species, mostly in the tropics and subtropics of both hemispheres. 

 1. Laportea canadensis (L.) Wedd. 



Monoecious perennial herb to about 1 m. tall, usually much less, beset with 

 stinging hairs; stem often flexuous; leaves alternate, broadly ovate, long-petioled, 

 7-20 cm. long, acuminate-attenuate at apex, rounded to broadly cuneate at base, 

 coarsely serrate, strongly feather-veined; stipule single, 2-cleft; staminate flowers 

 in cymes from the lowest leaf axils, seldom surpassing the subtending petioles; 

 pistillate flowers in loose elongate spreading divaricately branched cymes in the 

 upper leaf axils, usually much-surpassing the petioles; fruiting cymes divergent; 

 achenes flat, crescent-shaped, 3-4 mm. long. 



Low alluvial woodlands and along banks of streams, often forming large 

 colonies, in n.e. Okla., June-Aug.; N. S. to Man., s. to Ga. and Okla. 



2. Boehmeria Jacq. False Nettle 



Herbs, shrubs or small trees, devoid of stinging hairs, monoecious or dioecious; 

 leaves opposite or alternate, stipulate; flowers clustered, axillary; staminate flowers 

 minute, with a 4-parted calyx and 4 stamens; pistillate flowers with a tubular 

 or urceolate entire or 2- to 4-toothed calyx enclosing the ovary; style filiform- 

 subulate, persistent, stigmatic and papillose down one side; fruit formed by the 

 dry accrescent calyx that closely invests the elliptic achene. 



About 100 species mostly in tropical regions of both hemispheres. 



1. Leaf blades thinnish, coarsely serrate; petioles usually about as long as the 

 blades 1. B. cylindrica var. cylindrica. 



1. Leaf blades leathery, finely serrate; petioles much shorter than the blades 



1. B. cylindrica var. Drummondiana. 



1. Boehmeria cylindrica (L.) Sw. Bog-hemp, false nettle, button-hemp. 

 Fig. 396. 



Perennial, usually dioecious, glabrous to pubescent or even scabrous, erect, 

 to about 12 dm. high, the stem simple or rarely branched; leaves mostly long- 

 petioled, opposite or rarely alternate, ovate to ovate-lanceolate or oblong- 

 lanceolate, the blade to about 15 cm. long and 8 cm. wide, rather thin to leathery, 

 smooth to scabrous, acuminate at apex, rounded to somewhat cordate at base, 

 serrate, 3-nerved; stipules distinct; flowers about 2 mm. broad, unisexual, the two 

 kinds sometimes intermixed, the small clusters densely aggregated in simple and 

 elongated axillary spikes, the staminate spikes interrupted, the pistillate spike often 

 continuous and frequently leaf-bearing at apex; fruit ovate to suborbicular, com- 

 pressed, minutely winged, apiculate, hairy, to 1.5 mm. wide. 



In bogs, marshes, swamps, seepage areas and in wet soil and water along rivers 

 and streams in sun or shade, throughout e. Okla., n.w. to Woodward Co., mostly 

 in e. Tex. but extending w. to Val Verde Co. in w. Edwards Plateau and n. to 

 Hemphill Co. in the High Plains, June-Oct.; from Fla. to Tex., n. to Ont. and 

 Que., w. to Minn., Neb. and 111. 



Those plants that are usually in more exposed situations than var. cylindrica 

 and have narrower, oblong-lanceolate, thicker leaves with petioles mostly 2 cm, 

 or less long and harshly scabrous above and pubescent beneath are segregated as 

 var. Drummondiana Wedd. (5. scabra Small). The leaves also are commonly 

 recurved to give the plant a drooping appearance, and the fruiting spikes are 

 more dense and thicker and the fruits larger than in var. cylindrica. 



791 



