GENHRAL ASPHCT OF TllH FLORA. 



The boundaries of Tennessee are embraced within the j^reat 

 Atlantic forest region. The whole of it was in its virgin state, 

 a congeries of varied woodlands, being in the lowlands of dense 

 and massive growth, filled with ])athless jungles of cane and 

 shrub, or, away from the watercourses, on the uplands, reduced 

 to open and airy groves, the barrens. Here a dense sward covers 

 the ground and herbaceous growth prevails. Mountain forests 

 have always been of greater uniformity in distribution of timber. 



Nearly one-third of the entire area is now reduced to fields 

 or occupied by buildings or roads. Canebrakes have well nigh 

 disappeared, and the forest is in all accessible regions de[)leted 

 of valuable timber. 



Immigration of foreign and retirement ot native species con- 

 tinually modify the aboriginal flora a. id tend to weaken charac- 

 teristics due to presence of peculiar plantforms, or eollocati(>n of 

 >?pecies, by the intricacies of mutual })redileetion and adaptation 

 to surroundings. 



Such area-^, wdiich diifer amongst themselves conspicuously in 

 such properties, admit of the establishment of natural flora! 

 ar ro n disc men ts. 



Differences of elevation, diversity in elementary constitution 

 of the soil, and inequality in distribution of atmospheric humid- 

 ity are, in our territory, sufficiently pt)tent to mark out four dis- 

 tinct regions. 



I. The high crests of the Alleghany Mountains, formed of 

 gneiss or mica-shists, with an elevation tVom. 1,()(H) lo (ijiOO feet. 

 Snbalpine region. 



II. The western slopes of the Alleghanies an<l their outlying 

 spurs, and the Cumberland Mountains. Sandstones and slates. 

 Mountain-flora. Elevation "2-4,000 feet. 



III. Valley-flora, the lower division of wiiich i> coextensive 

 with the limestones (silurian) of Ea>l and Middl-' Tennessee. 

 Elevation 350-500 feet. The upi)er division or highlands has 

 siliceous and argillaceous soils, sometimes limestones of the sub- 

 ■carboniferous formation. l^lcvation ai)oni I .niMi - 1 /joo feet. 



