URTICACEAE (NETTLE FAMILY) 345 



achene in fruit. Embryo curved or coiled. — Herbs with watery juice, mostly opposite lobed 

 or divided leaves and persistent stipules. 



4. Cannabis. Fertile flowers spiked-clustered. Leaves 5-7 -divided. Erect. 



5. Hamulus. Fertile flowers in a short spike forming a membranaceous catkin In fruit. 



Leaves 3-5-lobed. Climbing. 



Tribe IV. m6rEAE. Flowers unisexual ; calyx becoming fleshy or juicy in fruit. Anthers in- 

 flexed in the bud. Ovule pendulous. Fruit an achene. Embryo curved. — Trees or shi-ubs, 

 with milky juice, alternate leaves, and fugacious stipules. 



6. Madura. Sterile flowers in loose racemes ; fertile in globose heads. Leaves entu-e. 



T. Broussonetia. Sterile flowers in dense catkins ; the fertile in globose heads. Leaves serrate, 

 often lobed. 



8. Morus. Fertile and sterile flowers in separate spikes. Leaves dentate, 3-nerved. 



Tribe v. URXfCEAE. Flowers unisexual. Filaments inflexed in the bud. Style or stigma 

 simple. Ovary 1-celled, -with an erect ovule, forming an achene in fruit. Embryo straight. — 

 Herbs with watery juice. 



* Calyx in the fertile flowers of 2-5 separate or nearly separate sepals. 

 ■»- Plant beset with stinging bristles. 



9. Urtica. Sepals 4 in both fertile and sterile flowers. Achene straight and erect, inclosed by 



the 2 inner and larger sepals. Stigma capitate-tufted. Leaves opposite. 



10. Laportea. Sepals 5 in the sterile flowers, 4 in the fertile, or apparently only 2. Stigma long- 



subulate. Achene very oblique, deflexed, nearly naked. Leaves alternate. 



-J- +- Plant whoUy destitute of stinging bristles ; leaves opposite. 



11. Pilea. Sepals 3 or 4, those of the fertile flowers unequal, all or all but one small, Achene 



partly naked, straight and erect. Stigma pencil-tufted. Smooth and shining, 



* * Fertile calyx tubular or cup- shaped, inclosing the achene ; unarmed. 



12. Boehmeria, Flower-clusters spiked, not involucrate. Style long and thread-shaped, stig- 



matic down one side. Leaves opposite, serrate. 



13. Parietaria. Flowers in involucrate-bracted clusters. Stigma tufted. Leaves alternate, 



entire. 



1. ULMUS [Tourn.] L, Elm 



Calyx 'bell-shapecl. 4-0-cleft. Stamens 4-9, with lono; and slender filaments. 

 Ovary 1-2-celled, with a single anatropous ovule suspended from the summit of 

 each cell; styles 2, short, diverging, stigmatic along the inner edge. Fruit a 

 l-celled and 1-seeded membranaceous samara. Albumen none ; cotyledons large. 

 — Flowers purplish or yellowish, in lateral clusters. Leaves strongly straight- 

 veined, short-petioled, and oblique or unequally somewhat heart-shaped at base. 

 Stipules small, caducous, (The classical Latin name.) 



* Flowers nearly sessile; fruit orbicular^ not ciliate ; leaves very rotigh above. 



\. U. fulva Michx. (Slippery or Red E.) Buds before expansion soft- 

 downy with rusty hairs ; leaves ovate-oblong, taper-pointed, doubly serrate, 1-2 

 dm. long, sweet-scented in drying, soft-downy beneath or slightly rough down- 

 ward ; branchlets and pedicels downy ; calyx-lobes and stamens 5-9; frnit {1.6- 

 1.8 cm. wide) with the cell pubescent. —Rich soil, w. Que. and N. E. to L. Huron, 

 the Dakotas, and soutliw. Mar., Apr. — A small or middle-sized tree (15-20 m. 

 high), with tough reddi.sh wood, and a very mucilaginous inner bark. 



2. U. CAMPESTRis L. (English E.) A large irregularly branched tree with 

 glabrous pedicels and large suborbicular glabrous fruit. — Commonly planted for 

 shade, and tending to e.scape. —Variable; some forms with corky-winged 

 branchlets. (Introd. from Eu,) 



* * Flowers on slender drooping pedicels, which are jointed above the middle; 



fruit ovate or oval, fringed-ciliate ; leaves smooth above or nearly so. 

 -*- Floioers vernal, appearing before the leaves. 



3. U. americana L. (American or White E.) Buds glabrous; branches 

 not corky ; leaves obovate-oblong or oval, abruptly pointed, sharply and often 



