14 



THE KINDS OF PLANTS 



families. More than 100 genera and 1500 species. Eepresentatives 

 are elm, hackberry, mulberry, osage orange, nettle, hop, hemp. 



A. Trees. 



B. Fruit a samara 1 . Ulmus 



BB. Fruit a small drupe 2. Celtis 



BBB. Fruit as large as an orange, formed of the whole mass of 



the pistillate flower-cluster 3. ToxyJon 



BBBB. Fruit resembling a blackberry, formed of the pistillate 



flower-cluster 4. Morus 



AA. Herbs. 



B. Leaves digitately lobed or divided. 



C. Plant standing erect 5. Cannabis 



cc. Plant twining 6. ffumulus 



Bb. Leaves not lobed : plant with stinging hairs 7. Urtica 



\. tLMUS. Elm. 



Trees, mostly large and valuable for timber, with rough-furrowed bark: 

 leaves alternate (2-ranked), ovate and straight-veined, dentate: flowers small 

 and not showy, appearing in earliest spring, sometimes diclinous, the calyx 

 4-9-parted, the anthers 4-9 on long filaments: ovary generally 2-loculed, 

 ripening into a 1-seeded wing-fruit. 



a Leaves large, roitgh on the upper surface: fruit large, nearly orbicular. 



U. fiilva, Michx. Slippery elm. Fig. 448. Middle-sized or small tree 



with inner bark mucilaginous or " slippery " in spring: leaves 6-8 in. long 



and half or more as broad, ovate elliptic and unequal-sided, doubly serrate, 



448. Ubnus fulva. 



449. Ulmus Americana. 



450. Ulmus racemosa. 



very rough above and softer beneath: samara ]4-% in. long, orbicular or 

 nearly so, with the seed in the center: flowers in dense clusters. Common, 

 aa. Leaves not very rough above: fruit oval, deeply notched at the apex. 

 IT. Americd,na, Linn. Common or white elm . Figs. 91-95, 146, 449. Tall and 

 graceful tree: leaves elliptic-oval, serrate: samara small, more or less hairy 

 on the thin wing, the notch in the apex extending nearly to the seed: flowers 

 banging on slender stalks. One of the finest of American trees. 



