446 URTICACE^E. (NETTLE FAMILY.) 



9. PARIETARIA, Tourn. PELHTORY. 



Flowers monceciously polygamous ; the staminate, pistillate, and perfect in- 

 termixed in the same involucrate-bracted cymose axillary clusters ; the sterile 

 much as in the last ; the fertile with a tubular or bell-shaped 4-lobed and nerved 

 calyx, enclosing the ovary and the ovoid achenium. Style slender or none : 

 stigma pencil-tufted. Homely, diffuse or tufted herbs, not stinging, with alter- 

 nate entire 3-ribbed leaves, and no stipules. (The ancient Latin name, because 

 growing on old walls.) 



1 . P. Pennsylvnica, Muhl. Low, annual, simple or sparingly branched, 

 minutely downy ; leaves oblong-lanceolate, thin, veiny, roughish with opaque 

 dots ; flowers shorter than the leaves of the involucre ^ stigma sessile. Shaded 

 rocky banks, Vermont to Wisconsin and southward. June - Aug. 



10. CANNABIS, Tourn. HEMP. 



Flowers dioecious ; the sterile in axillary compound racemes or panicles, with 

 5 sepals and 5 drooping stamens. Fertile flowers spiked-clustered, 1-bracted: 

 the calyx of a single sepal enlarging at the base and folded round the ovary. 

 Embryo simply curved. A tall roughish annual, with digitate leaves of 5-7 

 linear-lanceolate coarsely toothed leaflets, the upper alternate ; the inner bark 

 of very tough fibres. (The ancient name, of obscure etymology.) 



1. C. SATIVA, L. (HEMP.) Waste and cultivated ground. (Adv. from 

 Eu.) 



11. HUMULUS, L. HOP. 



Flowers dioacious ; the sterile in loose axillary panicles, with 5 sepals and 5 

 erect stamens. Fertile flowers in short axillary and solitary spikes or catkins : 

 bracts foliaceous, imbricated, each 2-flowered, in fruit forming a sort of mem- 

 branaceous strobile. Calyx of a single sepal, embracing the ovary. Achenia 

 invested with the enlarged scale-like calyx. Embryo coiled in a flat spiral. 

 Twining rough perennials, with stems almost prickly downwards, mostly oppo- 

 site heart-shaped and palmately 3 - 7-lobed leaves, with persistent ovate stipules 

 between the petioles. (Name thought to be a diminutive of humus, moist earth, 

 from the alluvial soil where the Hop spontaneously grows.) 



1. H. Ltlpulus, L. (COMMON HOP.) Leaves mostly 3-5-lobed, and 

 commonly longer than the petioles; bracts, &c., smoothish; the fruiting calyx, 

 achenium, &c., sprinkled with yellow resinous grains, giving the bitterness and 

 aroma of the hop. Alluvial banks : common northward and westward, where 

 it is clearly indigenous, July. (Eu.) 



ORDER 100. PL.ATANACE^E. (PLANE-TREE FAMILY.) 



Trees, with watery juice, alternate palmately-lobed leaves, sheathing stip- 

 ules, and monoecious flowers in separate and naked spherical heads, destitute 

 of calyx or corolla; the fruit merely club-shaped l-seeded nutlets, furnished 

 with bristly down along the base : consists only of the following genus (of 

 uncertain relationship). 



