354 Tlie Neiv York State College of Forestry 



WALNUT FAMILY. JUGLANDACEAE 



The walnut family consists of aromatic trees with watery juice, 

 alternate, estipulate, odd-piniiately compound, deciduous leaves, 

 monoecious flowers, and a fruit which is a nut. They are chiefly 

 confined to the warmer parts of the north temperate zone. Two 

 genera occur in North America, each of which is represented in 

 New York State. 



Leaves alternate, deciduous, odd-xjiunate, estipulate, with long, grooved 

 petioles; leaflets sessile or subsessile aside from the terminal, arranged in 

 pairs along the rachis. Flotvers monoecious, appearing after the leaves; 

 staminate flowers in elongated drooping aments on the growth of the previous 

 season or at the base of the growth of the season, each flower in the axil of 

 a bract; calyx 3-6 lobed adnata to the subtending bract; pistillate flowers 

 :in terminal spikes or terminal and solitary, generally subtended by a bract 

 and 2 bracteoles; calyx 3-5 lobed, adnate to the ovary; pistil consisting of a 

 1-eelled or incompletely 3-4 celled, 1-ovuled ovary terndnated by a short 

 style and 2 plumose stigmas. Fruit a bony nut, indehiscent or dehiscent with a 

 4-valved exocarp; seed large, solitary, 2-lobed, oily, exalbuminous; cotyledons 

 fleshy. 



KEY TO THE GENERA page 



1. Staminate aments simple, sessile or short stalked; husk of the nut indehiscent; 



pith diaphragmed Juglans 354 



1. Staminate aments branched, long stalked; husk of the nut 4-valved; pith 



homogeneous Carya 355 



THE WALNUTS AND BUTTERNUTS. Genus JUGLANS L. 

 Trees with spreading crowns, stout branches, superposed buds, 

 diaphragmed pith, and alternate, odd-pinnate leaves with sessile 

 or nearly sessile leaflets. About ten species are known, four of 

 Avhich occur in the United States, two in the eastern states, one 

 in the Pacific Coast region and one in the southwest. 



Leaves alternate, odd-pinnately compound, consisting of 11-17 sessile or 

 nearly sessile leaflets; leaflets oblong-lanceolate, acute at the apex, inequi- 

 lateral at the base, finely serrate except at the base, arranged aside from the 

 terminal in pairs along a stout pubescent xDetiole. Flowers monoecious, vernal^ 

 staminate flowers in drooping, cylindric aments 3-6 inches long borne on the 

 twigs of the previous season; perianth 3-6 lobed; stamens 8-40 in 2 or more 

 series; pistillate flowers in few-flowered spikes terminating the growth of 

 the season; perianth adnato to the ovary, 4-lobed; petals 4, small, adnate to 

 the ovary at the sinuses; pistil consisting of a usually 2-celled ovary, a short 

 style and 2 plumose stigmas. Fruit a globose or ovoid nut with fibrous, 

 somewhat fleshy, indehiscent exocarp and thick-walled, bony, rugose or sculp- 

 tured, indehiscent endocarp; seed exalbuminous, deeply lobed, oily, edible. 



KEY TO THE SPECIES page 



1. Leaflets 1.5-23; fruit subglobose, not viscid I. nigra 143 



1 . Leaflets 11 17; fruit ovoid and pointed, viscid J. cinerea 141 



