346 



THE KINDS OF PLANTS 



as the lobes of the calyx and opposite them: ovary superior, ripening 

 into a 1-seeded indehiscent, often winged fruit. A very polymorphous 

 association, by some botanists divided into two or three coordinate 

 families. More than 100 genera and 1,500 species. Representatives 

 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. Madura 



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. Humulus 



BB. L.eaves not lobed: plant with stinging hairs 7. Urtica 



507. Ulmus fulva. 



508. Ulmus americana. 



509. Ulmus racemosa. 



1. tfLMUS. 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, rough on the upper surface: fruit large, nearly orbicular. 



U. fulva, Michx. Slippery elm. Fig. 507. 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, very rough above and softer beneath: samara %-% in. long, 

 orbicular or nearly so, with the seed in the center: flowers in dense 

 clusters. Common. 



