1904.] LECTURE. 55 



(leptli of several IVet, llic roots, of course, must have air. Tins 

 is conveyed through the hollow projections wliich grow on the 

 roots and rise at least high enougli to he above the usual high- 

 water mark. If the water rises so high as to cover these for 

 many weeks, the trees die. 



This is the generally accepted theory of the knees, still they 

 have beeii a matter of six'culation to the botanists. Michaux 

 writes, "no caus(> can be assigned for their existence." Dr. 

 Gray writ(>s, ''the use to the trees of the knees is unknown." 

 Som(> authorities believe that their purpose is to strengthen 

 the root system. Mr. Lamborn writes, "I am convinced that 

 the most important function of the cypress knee is to stiffen 

 and strengthen the root, in order that a great tree may anchor 

 itself safely in a yielding material. When the trees grow in 

 firm grountl or where the roots can obtain a hold in the ordinary 

 way knees seldom if ever develop." 



The wood of the cypress is very valual)le for lumber, being 

 used for a great variety of purposes, and varying in color with 

 different localities. In the last twenty years it has largely 

 taken the place of white pine, which has become more and 

 more scarce in the market. In the vicinity of the Gulf of 

 Mexico, the largest trees are found. 



No other trees grow surrounded by so much water, and for 

 centuries they have stood in marshes, apparently undisturbed 

 by storm or flood. On the Ashley river, near Charleston, 

 TiUandria, or southern moss, grows upon its branches. This 

 I)lant loves moisture and in the damp woods of the South 

 often veils these trees with its abundant growth. 



As we left the lowdands for the mountainous district we found 

 coniferous trees fewer and the deciduous trees more and more 

 apparent. Red birches (Betida nigra) grow along the banks 

 of the Swananoa river at Biltmore, where they attain great 

 size. These trees are estimated to be one hundred and fifty 

 j'^ears old or more. Beneath their shade along the banks 

 grows a tall reed or cane, resembling bamboo. 



A short distance from Biltmore, the estate of W. K. Vander- 

 bilt, we saw the Carolina hemlock {Tsiiga Caroliniana), and 



