APETALOUS EXOGENOUS PLANTS. 493 



long-lanceolate, obtuse, roughened with minute elevated 

 dots; clusters dense; flowe?'s shorter than the involucre. 

 Shaded rocks in the upper districts. May-July. Stem 

 4-12' high; leaves 6"-9" long. Annual. 



BOEHMERIA, Jacq. False Nettle. 



Floioers monoecious or dioecious, in spiked clusters; 

 calyx of the sterile flowers 4-5-cleft; stamens 4^5; calyx 

 of the fertile flowers tubular, 4-5-toothed or entire ; stigma 

 subulate, hairy; achejiium elliptical, inclosed in the per- 

 sistent calyx. — Rough lierhSf witli alternate or opposite 

 petioled leaves. 



B. CYLINDRICA, Willd. Pubesceut and rough with 

 straight and hooked hairs; leaves opposite and alternate, 

 ovate and ovate-lanceolate, acuminate, serrate, rounded 

 and 3-nerved at the base, on long or sliorfc petioles ; spikes 

 axillary, mostly leafy at the summit, the fertile ones com- 

 pactly flowered, short, the sterile interrupted, and some- 

 times longer than the leaves. Swampy thickets. July- 

 September. Stem l°-3° high, mostly simple ; leaves 2-5' 

 Ion ST. Perennial. 



115. HEMP FAMILY. Order, Cannabinace^. 



Erect or twining lierhs, with opposite incised or lobed 

 and stipulate leaves, iixid diQ^ciows floioers ; sterile flowers 

 racemose or panicled; calyx 5-sepalous; stamens 5, oppo- 

 site the sepals, not inflexed in the bud; fertile flowers in 

 bracted spikes ; calyx 1-leaved, embracing the 1-celled 

 ovary ; ovule solitary, erect ; stigmas 2, subulate, pubescent ; 

 fruit indehiscent ; albumen none ; embryo coiled or curved. 



HUMULUS, L. Hop. 



Sterile floivers 'po.moled; fertile flotvers in short axillary 

 and solitary spikes; bracts leafy, imbricated, 2-flowered, 



