/. 



KEY, BASED UPON FLOWERS. 

 i 2 . Before the leaves in short umbels ; young fruit wooly 



26. A. DASYCARPUM. 



7* 2 . Leaves compound ............... ..... ....... 54. A. NEGUNDO. 



gr 2 . Single 1-celled and 1-seeded samara (Fraxinus), which is 

 h. Terete at base ; lateral leaflets 

 *. Petiolulate and new growth 



Smooth ................................. . . 10. F. AMERICANA. 



Pubescent ................ ............. . ....... 31. F. PUBESCENS. 



i" 2 . Sessile or nearly so ; leaves tomentose ............ 167. F. OREGONA. 



Broad at base .................................... 62. F. SAMBUCIFOLIA. 



Capsule 3-celled each cell with a single seed ____ 189. RICINUS COMMUNIS. 



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

 (j. Anthers opening by uplifted valves ; stigma single and entire (Laitracece) ; 



flowers 

 h. Perfect ; leaves evergreen ; calyx lobes 



Persistent (Persea) ......................... 113. P. CAROLINENSIS. 



Deciduous ( Umbellularia] .................. 159. U. CALIFORNICA. 



7t 2 . Dioecious, calyx deciduous, leaves deciduous; involucre none 



(Sassafras) ............................... 32. S. OFFICINALE. 



</. 2 Anthers extrorse ; stigma 2-cleft ; fruit a 

 h. Samara, 1-celled and winged all round (Ulmus). 



i. Flowers nearly sessile ; samara not ciliate-fringed ; leaves very rough 

 above ____ " .................................. 11. U. FULVA. 



i 2 . Flowers on drooping pedicels ; samara ciliate-fringed ; leaves smooth. 

 Bud-scales glabrous ; flo\vers fascicled ; branches not corky-winged 



33. U. AMERICANA. 



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



34. U. RACEMOSA. 

 /t 2 . Capsule, dry, nut- like, not winged (Planera) ....... 114. P. AQUATICA. 



# 3 . Anthers introrse ; fruit a dark-purple drupe, leaves long-taper-pointed 



12. CELTIS OCCIDENTALS. 

 <y 4 . Anthers laterally dehiscent ; fruit a drupe. 



111. FORESTIERA ACUMINATA. 



1 . One or both sorts of flowers in catkins, diclinous. 

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

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



(Juglandacece) . 

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



(Juglans) . 

 (j. Fruit ovoid-oblong and viscid-hairy ................... 14. J. CINEREA. 



</ 2 . Fruit subglobose 



li in. or more in thickness, roughly dotted ........... 35. J. NIGRA. 



l| in. or less in thickness, pubescent .......... 190. J. CALIFORNICA. 



/-. Corolla not present in the fertile flower ; fruit with usually 4-valved 



epicarp (Carya) which is 

 </. Thick ; valves separating to base ; bark 

 h. In loose plates ; leaflets 



5, smoothish ; nut small .............................. 36. C. ALBA. 



7-9 ; nut large .................................. 64. C. SULCATA. 



7* 2 . Close, leaflets 7-9, tomentose ...................... 90. C. TOMENTOSA. 



g*-. Thin ; bark close ; nut 

 h. Quite smooth, small, thin-shelled, leaflets 



5-7 ; kernel edible .......................... 91. C. MICROCARPA. 



7-9 ; kernel very bitter ........................... 37. C. AMARA. 



7i, 2 . More ridged, larger, thicker-shelled ; leaflets 5-9 ...... 65. C. PORCINA. 



/i 3 . Rugose, angular ; leaflets 11-13 .................... 115. C. AQUATICA. 



e 2 . Fertile flowers 1-3 together, invested wholly or partly with an involucral 



covering ; leaves simple (Ctipuliferce). 

 f. Involucre valveless, cup-like, composed of many scales and only partly 



inclosing the one nut, i. e., acorn (Quercus); staminate aments 

 (j. Pendulous (section Lepidobalanus) , stigmas 



h. Sessile or nearly so and dilated ; stamens 6-8; abortive ovules mostly 

 basal (subsec. Leucobalanus, WHITE OAKS) ; maturation 



