KEY, BASED UPON FLOWERS. 3 



3 . Apetalous without petals. 

 c. Flowers not in catkins; pistil one, simple or compound, and the cells of the 



ovary containing 1-2 seeds each. 



d. Ovary inferior aduate its whole length to the calyx-tube 1 -celled and 

 1-seeded; style 1, stigraatic down the side (Nyssa); fertile peduncles bear- 

 ing each two or more flowers 9. N. MULTIFLORA. 



d-. Ovary superior free from the calyx. 



e. Stipules sheathing the stem; trees with naked monoecious flowers ar- 

 ranged in heads 13. PLAT ANUS OCCIDKNTALIS. 



'. Stipulates not sheathing the stem or none. 

 /. Ovules a pair in each cell of the ovary which becomes in 

 ff. Fruit a double samara (Acer). 



h. Leaves simple and palmately veined; flowers appearing 



i. With the leaves in pendulous corymbs 7. A. SACCHARINUM. 



i*. Before the leaves in short umbels, and 



Apetalous; young fruit wooly 26. A. DASYCARPUM. 



Petals present, linear-oblong; fruit smooth. .53. A. RUBRUM. 

 i 3 . After the leaves in drooping racemes 



79. ACER PENNSYLVANICUM. 



h-. Leaves compound 54. A. NEGUNDO. 



f/ 2 . Fruit a 1-celled and 1-seeded samara (Fraxinu*). 

 h. Samara terete at base; leaflets petiolate 



New growth smooth 10. F. AMERICANA. 



Xew growth pubsecent 31. F. PUBESCENS. 



7i 2 . Samara broad at base 62. F. SAMBUCIFOLIA. 



f*. Ovules single in each of the 1 or 2 cells of the ovary. 



f/. Anthers opening by uplifted valves ; stigma single and entire; flowers 



dio3cious ; stamens 9 ; anthers 4-celled ; involucre none ; fruit an 



ovoid, blue drupe with reddish pedicel. .32. SASSAFRAS OFFICINALE. 



</-. Anthers extrorse ; stigma 2-cleft ; fruit a 1-celled samara winged 



all round (Ulmus). 

 h. Flowers nearly sessile ; samara not fringed ; ciliate ; leaves very 



rough above 11. U. FULVA. 



7* 2 . Flowers on drooping pedicels ; samara ciliate-fringed ; leaves 



smooth. 



Bud-scales glabrous ; flowers fascicled ; branches not corky- 

 winged 33. U. AMERICANA. 



Bud-scales downy-ciliate ; flowers racemed ; branches corky- 

 winged 34. U. RACEMOSA. 



gr 3 . Anthers introrse ; fruit a dark-purple drupe ; leaves long-taper- 

 pointed 12. CELTIS OCCIDENTALIS. 



C 2 . Flowers diclinous and one or both sorts in catkins. 

 d. Only one sort (the staminate flowers) in catkins. 



e. Fertile flowers single or clustered ; fruit naked ; leaves pinnately com- 

 pound (Juglandacece). 



/. Corolla present in the fertile flowers ; fruit with valveless epicarp 

 (Juglins). 



ff. Fruit ovate, oblong and viscid-hairy 14. J. CINEREA. 



g*. Fruit globose, roughly dotted (not viscid-hairy) 35. J. NIQRA. 



