JUGLANDACEAE 59 



6 genera in the N. temperate zone. The largest genus is Hicoria 

 with 11 species, at one time thought to be pure]}- American, but 1 species 

 has been described from Chekiang. 



KEY TO GENERA 



A. Branches with chambered pith. 



I. Fruit a large drupe with a fleshy indehiscent husk Juglans m 



II. Fruit a winged nutlet Pterocai-ya. 



B. Branches with solid pith. 



I. Fruit a large nut enclosed in a woody dehiscent husk. . . .Hicoria. 

 II. Fruit a nutlet, many together 



a. Nutlets winged, borne in a scaly cone Platiicarya. 



b. Nutlets not winged, embraced at the base by a 3-lobed 

 bract Englehardtia. 



JUGLANS 



Trees with pith in horizontal plates. Leaves deciduous, alternate, 

 compound, aromatic, without stipules. Leaflets opposite, sessile or 

 subsessile, entire or serrate. Flowers monoecious. Staminate flowers in 

 slender, drooping catkins borne on the twigs of the previous year's 

 growth; perianth 2-5 lobed ; stamens 6-30, in several series. Pistillate 

 flowers few to many in a terminal erect spike, on the twigs of the current 

 year's growth; calyx 4 lobed; involucre 2-5 parted, adnate to the ovary; 

 ovarj* inferior, 1 celled, 1 ovuled. Fiuit a large drupe with a thick, 

 flesh}', indehiscent husk enclosing a hard-shelled, bony, sculptured nut. 

 Nut 2-4 celled at the base, indehiscent, or splitting into 2 valves. Seeds 

 solitary, lobed, exalbuminous, filling the cavity of the nut. The 

 cotyledons remain in the ground at germination. 



About 15 species scattered through N. and S. America, Europe and 

 Asia. 



Juglans regia Linnaeus. 

 Walnut. 



Trees to 25 m. tall. Leaves large up to 25 cm. long; leaflets 5-13, 

 the terminal one stalked, others subsessile, oblong-ovate or elliptic-oblong, 

 acute or acuminate, entire or sinuate, glabrous, dark green above, pale 

 green beneath, 5-15 cm. long. Pistillate flowers 1-4, usually green with 



