72 



PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



The following specimens of Uhnus americana have been measured by 

 me : 



Flowers March 10 to 20, and begins to leaf the last week in April. 



49.(179.) Ubnusfulva. " Slippery Elm." 



A common tree in rich woods, but much less abundant than U. amer- 

 icana. Grows commonly from 50 to 70 feet high, and 1^ to 2 feet in 

 diameter, although much larger specimens undoubtedly occur. No 

 measurements, however, have been taken. 



50. (183.) Celtis mississippiensis. Mississippi Hackberry. 



A very common tree, though less numerous than C. occidentalism with 

 which it is found associated in very rich bottoms. It is usually a 

 smaller tree than that species, commonly 60 to 80 feet high, the branches 

 growing lower down, the bark of the trunk covered with prominent 

 warty excrescences, and the leaves smaller, more coriaceous, and entire. 

 The only specimen measured was 60 feet high and 11 in circumference. 



51. (184.) Celtis occidentalis. Hackberry. 



A very tall and beautiful tree in rich bottoms, growing frequently 120 

 to 130 feet high and 3 feet in diameter, with a tall, straight trunk of 60 

 to 70, or even 80, feet to the first limb. When growing to its full per- 

 fection iu a dense forest, there is an individuality in the aspect of this 

 tree which it is difficult to describe. It does not excel either in height 

 or girth, yet it has the appearance of being one of the very tallest trees 

 in this lofty forest, this illusion being doubtless due to the extreme slen- 

 derness and great length of the trunk, which not unfrequently comprises 

 three fourths of the total height of the tree, the smooth, gray bark con- 

 spicuously clouded on the north side, with blackish moss or lichen for 

 tiie entire length. This striking api)earance is sometimes still further 

 increased by vines of the Virginia Creei^er ascending to the topmost 

 branches, which are wreathed and matted with its foliage. Although 

 83 feet is the greatest length of the tape-line actually stretched along a 



