462 URTICACE^E. (NETTLE FAMILY.) 



9. 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. 

 t- H- Plant wholly destitute of stinging bristles. Leaves opposite 



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



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

 * * Fertile calyx tubular or cup-shaped, enclosing the achene. Unarmed. 



11. Boehmeria. Flower-clusters spiked, not iuvolucrate. Style long and thread-shaped, 



stigmatic down one side. Leaves opposite, serrate. 



12. Parietaria. Flowers in involucrate-bracted clusters. Stigma tufted. Leaves alter- 



nate, entire. 



1. ULMUS, L. ELM. 



Calyx bell-shaped, 4-9-cleft. Stamens 4-9, with long and slender fila- 

 ments. 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 1 -celled and 1 -seeded membranaceous samara, winged all around. 

 Albumen none ; embryo straight ; the cotyledons large. Flowers polyga- 

 mous, purplish or yellowish, in lateral clusters, in our species preceding the 

 leaves, which are strongly straight-veined, short-petioled, and oblique or un- 

 equally somewhat heart-shaped at base. Stipules small, caducous. (The 

 classical Latin name.) 



* Flowers nearly sessile ; fruit orbicular, not ciliate ; leaves very rough above. 



1. IT. flilva, Michx. (SLIPPERY or RED ELM.) Buds before expansion 

 soft-downy with rusty hairs (large) ; leaves ovate-oblong, taper-pointed, doubly 

 serrate (4 - 8' long, sweet-scented in drying), soft-downy beneath or slightly 

 rough downward ; branchlets downy ; calyx-lobes and stamens 5 - 9 ; fruit 

 (8-9" wide) with the cell pubescent. Rich soil, N. Eng. to the Dakotas, and 

 southward. March, April. A small or middle-sized tree (45-60 high), with 

 tough, reddish wood, and a very mucilaginous inner bark. 



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

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



2. U. Americana, L. (AMERICAN or WHITE ELM.) Buds and branch- 

 lets glabrous; branches not corky; leaves obovate-oblong or oval, abruptly 

 pointed, sharply and often doubly serrate (2-4' long), soft-pubescent beneath, 

 or soon glabrous ; flowers in close fascicles ; calyx with 7-9 roundish lobes ; 

 fruit glabrous except the margins (' long), its sharp points incurved and clos- 

 ing the notch. Moist woods, especially along rivers, in rich soil. April. A 

 large and well-known ornamental tree, variable in habit, usually with spread- 

 ing branches and drooping branchlets. 



3. U. racembsa, Thomas. (CORK or ROCK ELM.) Bud-scales downy 

 ciliate and somewhat pubescent, as are the young branchlets ; branches often 

 with corky ridges ; leaves nearly as in the last, but with veins more simple and 

 straight ; flowers racemed ; fruit much as in the last, but rather larger. River- 

 banks, S. W. Vt. to Ont. and central Minn., south to Mo. and Ky. A large 

 and very valuable tree. 



4. U. alata, Michx. (WAHOO or WINGED ELM.) Bud-scales and branch- 

 lets nearly glabrous ; branches corky-winged, at least some of them ; leaves 

 downy beneath, ovate-oblong and oblong-lanceolate, acute, thickish, small 



