58 



There are now recognized 1 fifteen species and several varieties of 

 hickory, all of which grow in the United States east of the Rocky 

 Mountains. Hickory grows in no other place in the world, except one 

 species in northern Mexico. The wood of the different species of hickory 

 is not of equal commercial vajue, but the wood of the commercial 

 species heads the list of Indiana woods for strength, toughness and 

 resiliency. 



The individuals of the several species vary much in respect to their 

 bark, size and pubescence of the twigs, number and size of the leaflets, 

 size and shape of the nuts. No attempt will be made to deal with all 

 of the extreme forms, and only those reported by Heimlich 2 and Sar- 

 gent 3 will be discussed. 



Bud scales 4-6, valvate (in pairs), leaflets generally curved 



backward. 

 Leaflets 9-17, generally about 13; nut elongated, circular in 



cross-section; kernel sweet 1 C. illinoensis. 



Leaflets 5-9, generally 5-7; nut about as broad as long, 



compressed in cross-section; kernel bitter 2 C. cordiformis. 



Bud scales more than 6, imbricated (not in pairs) ; leaflets not 



curved backward. 



Branchlets usually stout; terminal buds large, 7-25 mm. 

 long; the year's growth usually more or less hairy; dry 

 husks 4-10 mm. thick. 



Prevailing number of leaflets 5 3 C. ovata. 



Prevailing number of leaflets more than 5. 



Trees of low ground; bark of young trees tight and 

 light, of older trees scaly, separating into long thin 

 plates; branchlets usually light orange color; 

 nuts usually large, compressed, 3-6 cm. long, 



pointed at base 4 C. laciniosa. 



Trees of high ground; bark of young trees tight and 

 dark, of older trees tight and deeply furrowed, the 

 thick ridges broken into short lengths which on 

 very old trees loosen at the base; branchlets red- 

 dish-brown; nuts usually about half as large as 

 the preceding and usually with a rounded base. . . 5 C. alba. 

 Branchlets usually slender; terminal buds small, 5-12 mm. 

 long; the year's growth usually glabrous, rarely hairy; 

 dried husk 1-2.5 mm. thick. 



Branchlets and leaves not covered when they first appear 

 with rusty-brown pubescence. 



iSargent in Bot. Gaz. Vol. 64: 58:1918. 



2 Heimlich in Proc. Ind. Acad. Sci. 1917:437:439:1918 credits most of my records 

 jointly with Prof. G. N. Hoffer. This is an error. On my invitation Prof. Hoffer accompanied 

 me nine days in the field doing mycological work. While he gave me valuable assistance in 

 collecting during these days, his assistance and responsibility stopped there and he never 

 asked or expected to be considered joint author. Again on our trip we collected only in 

 Daviess, Gibson, Fountain, Knox, Lawrence, Martin, Pike and Sullivan Counties. 



sSargent I.e. 



