A KEY, BASED UPON THE FRUIT 



Designed as an Aid in identifying the Species represented in Parts I-VII 

 inclusive, when in Season for procuring the Fruit. 



N. B. The remarks concerning the use of the Key based upon the Leaves are 

 equally true with reference to this. 



a. Free Fruit. formed by the ripening of a single pistil either simple or com- 

 pound. 



b. Indehiscent pericarp. 



c. Samara dry, usually 1-celled, 1-seeded and with 1-2 membranous wings. 

 d. In terminal panicles; wing somewhat oblong-lanceolate, with a lenticu- 

 lar seed at about its center, and beyond which the wing is twisted 



(Ailanthus) 4. A. GLANDULOSUS. 



e? 2 . In terminal cymes, a 2-seeded suborbicular samara, winged all around. 



77. PTELEA TRIFOLIATA. 



d\ In umbellate corymbs, each pedicel supporting a pair of samarae with 

 oblanceolate wings, obtuse at the apex and with main rib on outer 

 margin (Acer). 

 e. Fruit maturing in the fall, wings slightly divergent. 



7. A. SACCHARINUM. 



e. 2 Fruit maturing in early summer. 



/. Large, 1 in. or more, downy when young 26. A. DASYCARPUM. 



f 1 . Smaller, smooth, pendulous and 



Red, in umbels 53. A. RUBRUM. 



Greenish, in racemes, wings incurved 54. A. NEQUNDO. 



d*. In terminal racemes, 2 samarae on a single pedicel with main rib on 

 outer margin ; seed- bearing portion. 



Glabrous 79. ACER PENNSYLVANICUM. 



Densely hairy 152. ACER MACROPH YLLUM. 



d*. In axillary racemes or panicles, winged at the apex with a more or less 



lanceolate obtuse wing (Fraxinus). 

 e. Terete at base (seed- bearing portion) ; branchlets and petioles 



Smooth 10. F. AMERICANA. 



. Velvety pubescent 31. F. PUBESCENS. 



e 2 . Flat wing extending along the seed-bearing portion. 



62. F. SAMBUCIFOLIA. 



d 6 . In lateral fascicles or clusters, winged all round ( Ulmus). 



Sessile or nearly so, cell pubescent and margin not ciliate. 



11. U. FULVA. 

 In fascicles, cell smooth, margin densely ciliate. .33. U. AMERICANA. 



In racemes, cell pubescent, margin ciliate 34. U. RACEMOSA. 



C. 2 Drupe or drupe-like and with a single seed. 

 d. Fibro-neshy and dryish pericarp. 

 e. Small, subglobose (Rhuft). in terminal. 



Thyrses and clothed with crimson hairs 5. R. TYPHINA. 



Spikes and clothed with viscid gray hairs 153. R. OVATA. 



e 2 . Large, about 2 in. in length, with edible embryo (Juglans) 



Ovoid or oblong and clothed with brownish fragrant-viscid hairs. 



14. J. CINEREA. 

 Globose, roughly dotted (not viscid hairy) 35 J. NIGRA. 



