URTICACE.^. (nettle FAMILY.) 435 



many as and opposite the sepals. Filaments inflexed in the bud, ex- 

 panding elastically : anthers 2-celled, intvorse. Calyx of the fertile 

 flower 2-4-sepalous. Ovary sessile, free, 1-celled, with a single erect 

 orthotropous ovule. Stigma simple or tufted. Achenium commonly 

 enclosed in the dry persistent calyx. Embryo straight, in the axis of 

 fleshy albumen. 



Synopsis. 



* Plants armed with stinging hairs. 



1. URTICA. Stamens 4. Stigma tufted. Achenium straight. 



2. LAPORTEA. Stamens 5. Stigma subulate. Achenium oblique. 



# # Plants destitute of stinging hairs. 

 •I- Flowers in cymose clusters. 



3. PILEA. Clusters naked. Calyx lobes unequal. Leaves opposite. 



4. PARIETARIA. Clusters involucrate. Calyx lobes equal. Leaves alternate. 



•I- -I- Flowers in spiked clusters. 



5. BOSHMERIA. Stigmas subulate, leaves opposite or alternate. 



1. URTICA, Tourn. Nettle. 



Flowers moncEcious or dioecious. Calyx of the sterile flower 4-parted. 

 Stamens 4, inserted around the abortive ovary. Calyx of the fertile flower 

 4-sepalous, unequal ; the inner sepals dilated in fruit, and enclosing the ache- 

 nium. Stigma ses.'^ile, tufted. Achenium straight, ovate, smooth, compressed. 

 — Herbs, with stinging hairs, opposite leaves, and greenish flowers, in pani- 

 cled spikes or close clusters. 



* Flowers in pam'cled or simple spikes. 



1. U. gracilis, Ait. Stem tall, 4-augled, smoothish, slender; leaves 

 long-petioled, ovate-lauceolate, coarseh' serrate, acute, rounded at the base, 

 3-5-nerved, smootliish, the petioles bristly; spikes very slender, loosely pani- 

 cled. — Low ground in the upper districts. July- Augu.st. ^ — Stem 3°- 

 4° high, mostly simple. Leaves thin, 4' -6' long. 



2. U. dioica, L. Hispid throughout ; stem 4-angled, pubescent above, 

 branching ; leaves rather short-petioled, ovate, cordate, acuminate, coarsely 

 serrate, pubescent beneath ; spikes much branched ; flowers often dice- 

 cious. — "Waste places, Carolina (P«rs/i). Introduced. June -August. "21 — 

 Stem 2° -3° high. Leaves 3' -4' long, thicker than in No. 1, and flowers 

 larger. 



* * Flmcers in simple clusters shorter than the petioles. 



3. U. urens, L. Stem 4 angled, hairy ; leaves ovate, coarsely serrate, 

 .5-nerved, hairy ; clusters J)y pairs in each axil, loose, peduncled. — Waste 

 ground. Litroduced. Dec. -Feb. (l) — Stem 1° high. 



4. U. Chamsedryoides, Pursh. Stem smooth ; leaves .small, nearly 

 sessile, ovate, coarsely .«errate hairy beneath, hairy and l)ristly above ; clus- 

 ters nearly sessile, gloliose, dense; calyx haify. — Georgia (Elliott), and west- 

 ward. Feb. - March. — Stem 4' - 12' high. 



