54 KANSAS UNIVERSITY SCIENCE BULLETIN. 



The four oaks may be distinguished by the thickness of the 

 bark in the current year's growth, and by the tissues of the 

 bark. 



There is a distinguishing difference in the number and size 

 of the medullary rays in the wood. 



CONCLUSIONS. 



No. 1 is the species described as Q. muhlenbergii and may 

 be identified macroscopically by its narrow leaves with sharply 

 acuminate, serrate teeth. The shell of the nut is twice as 

 thick in No. 1 as in Nos. 2, 3, and 4. Nos. 2 and 3 are possible 

 hybrid muhlenbergiis. They may be distinguished from No. 1 

 by their broader and more irregular leaves. No. 2 has large 

 acorns, and has a smooth bark for several years, while the 

 epidermis is broken up on Nos. 1 and 3 in the current year's 

 growth. The acorns of No. 3 are very small and the nut is 

 almost overgrown by the cup. A hand lens will reveal the 

 unusual number of epidermal hairs on the lower epidermis 

 of No. 3, which might well give it the variety name of 

 "hirsuta." 



No. 4 is enough different from the others to be classed as 

 a distinct species. It may be identified macroscopically by its 

 slightly paler leaves, smooth-barked twigs and a marked dif- 

 ference in the acorn cup, which is shallow, thin, and covered 

 with thin tightly appressed bracts, while those of Nos. 1, 2, 

 and 3 are generally deeper, thicker and covered with thick 

 bracts which make the cups irregular and rough. Either No. 4 

 or No. 2 is probably Quercus aleocanderi of Britton and I would 

 suggest that name be retained for No. 4. 



BIBLIOGRAPHY. 



Copeland, Mechanism of Stomata, Ann. of Bot. XVI, 1902, p. 327. 

 Schwendener, Bau u. Mechanism, d. Spaltoffn., Berliner Akad., 1881, 

 p. 833. 



