URTICACEAE. 127 



3 to 7-nerved, serrate, with stipules. Flowers in ours monoecious, clustered, the 

 clusters in axillary often branching spikes. Staminate flowers with 4 sepals, 



4 stamens and the cup-shaped rudiment of a pistil. Pistillate calyx with the 

 sepals unequal, the exterior smaller than the inner and at length enclosing the 

 flattened achene; ovary with sessile tufted or almost feathery stigma. Endo- 

 sperm scanty. (Ancient Latin name.) 



Pistillate and staminate flowers in separate spike-like inflorescences; the pistillate some- 

 what shorter than and in axils above the staminate; perennial. 



Herbage gray; leaves ovate to lanceolate 1. U. gracilis. 



Herbage dark green; leaves broadly ovate, cordate at base 2. U. California*. 



Pistillate and staminate flowers mixed in the same cluster; herbage dark green; annual. 



3. U. urens. 



1. U. gracilis Ait. var. holosericea Jepson. Creek Nettle. Stem strict, 

 unbranched, 4 to 10 ft. high; leaves long ovate to lanceolate, more or less 

 pubescent on both faces or the upper surface green and with scattered bristles 

 and the lower surface gray, 3 to 5 in. long; flowers sessile in small clusters, 

 these disposed in simple or somewhat paniculately branched spikes; spikes often 

 shorter than petioles. — (U. holosericea Nutt.) 



Moist valleys, marshes, damp spots in the hills and along creeks; common and 

 often abundant throughout California. 



2. U. californica Greene. Coast Nettle. Stem often branched from the 

 base, 2 to 4 ft. high, producing stolons; stems and petioles hispid and some- 

 what pubescent; leaves broadly ovate, deeply cordate, coarsely serrate, sub- 

 glabrous above, shortly pubescent below and often gray, 3 to 4 in. long and 

 nearly as broad, or the lower 4 to 7 in. long; spikes simple or paniculately 

 branched, mostly exceeding petioles. — (U. lyallii Wats. var. californica Jepson.) 



Low lands near the coast from San Mateo Co. northward to Marin Co. 



3. U. urens L. Small Nettle. Erect and simple or branching from the 

 base, 1 to 1% ft. high, leafy to the top, very sparingly hispid; leaves elliptic 

 or ovate, coarsely laciniate-serrate, 3 to 5-nerved, % to 1% in. long, slender 

 petioled; stipules short, about 1 line long; flowers more or less pediceled in 

 glomerules, the glomerules in an oblong rather dense spike often shorter than 

 the petioles; fruiting calyx with hispid-ciliate margins. 



Native of Europe, now widely naturalized in central and Southern California. 



2. HESPEROCNIDE Torr. 

 Annual herbs similar to Urtica. Stipules minute. Staminate calyx with 4 

 almost distinct sepals. Pistillate calyx consisting of a membranous flattened 

 oblong-ovate sac with a minutely 2 to 4-toothed orifice. (Greek hespera, west 

 or western, and knide, a nettle.) 



1. H. tenella Torr. Slender, erect or straggling, 1 or 2 ft. high; stems 

 and petioles bristly with scattered hairs, the blades very sparsely hispid; leaves 

 thin, ovate, serrately incised, y 2 to 1% (or 2) in. long on slender petioles; 

 flowers densely glomerate in the axils, the clusters shorter than the petioles; 

 pistillate calyx thin, hispid witli hooked hairs, in fruit \(_> to less than 1 line 

 long; achene with minutely roughened surface. 



Coast Ranges from Napa Valley southward to Southern California. 



Parietakia debills Foist. Annual; leaves alternate, entire, without stip- 

 ules; hairs not stinging; achene ovoid; pistillate calyx tubular, 4-cleft. — 

 Southern California. 



