82 PLANT LIFE OF ALABAMA. 



On the rugged foothills and mountain slopes, and particularly on the 

 broad, barren, limestone flats of the uplands in the eastern part of the 

 valley north and east of the Tennessee River the red cedar forms 

 extensive woods, of pure growth, interrupted only by bare openings 

 where the rocky ground scarcely affords a foothold to shrub or herb. 

 The trees in the cedar glades or cedar brakes are closely set and attain 

 a height of from 50 to 75 feet, the trunk from 15 to rarely 24 inches 

 in diameter, breast-high, frequently deeply ridged toward the base, 

 knotty, and with the crown from 30 to 50 feet or more above the ground. 

 Under these severe soil conditions the growth of the trees is exceed- 

 ingly slow, particularly during the later stages of life. By counting 

 the annual rings trees of the dimensions mentioned were found to be 

 from MO to 175 years old. Large supplies of the valuable timber of 

 the cedar, used for piling and for telegraph and telephone poles, are 

 drawn every year from the cedar glades. On the gentler slopes with 

 a deeper soil covering, and in the narrow valleys with a damp and rich 

 soil, red cedar occurs scattered among the hard woods and here reaches 

 its greatest perfection. The trunk is smooth from the base and free 

 from knots and limbs for the greater part of its height; the wood is 

 straight-grained, soft, and easily worked, and possesses all the quali- 

 ties for which it is so eagerly sought in the manufacture of pencil 

 casings and the best qualities of hollow ware. Not long since this tree 

 was abundant in the narrow valleys and rich coves south of the Ten- 

 nessee River, but these resources are now becoming rapidly exhausted. 



On the sunny exposures, in the openings and borders of the forest 

 which covers the calcareous hills, where the soil is deeper, a variety of 

 xerophile trees of small size and of shrubs of the lower belt of the 

 Carolinian area are found mingled with the red cedar. Examples are: 



Rhamnus caroliniana (buckthorn) . Crataegus cocdnea (red haw) . 



Bumelia lycioides (bumelia) . Cornus asperifolia (rough-leaf dogwood) . 



Bumelia lanuginosa (shittimwood) . Viburnum prunifolium (black haw) . 

 Ostrya virginiana (hop hornbeam) . 



Xerophile herbaceous plant associations. The herbaceous associations 

 are naturally, in the main, of xerophile character. On the exposed 

 rocky flats tiny cruciferous winter annuals fill every crevice. Leaven- 

 worthia aurea, L. uniftora, and L. torulosa, the first harbingers of 

 spring, are followed by Draba caroliniana and D. Irrachycarpa. With 

 the advent of warmer weather all herbaceous vegetation withers on 

 these arid cedar glades, which then continue to present the aspect of 

 absolute barrens. 



On the rocky banks and shelves of the sunny hillsides a varied array 

 of characteristic herbs makes its flowery display. In the height of 

 springtime, as observed on the southern slopes of Monte Sano(near 

 Huntsville) and on the northern declivity of the Warrior table-land 



