216 JOURNAL OF THE ARNOLD ARBORETUM [vol. ii 



Orleans; near Lake Charles, Calcasieu Parish, and near Natchitoches, 

 Natchitoches Parish. 



CAPRIFOLIACEAE 



Sambucus canadensis L. Frequently arborescent, with a height of 30 

 feet and a trunk 2 feet in diameter. Flowers March 28 to April 15. 



Sambucus Simpsonii Rehd, A tall shrub or small tree; rich woods near 

 Opelousas. Flowers April 15, 



Viburnum rufidulum Raf. On rolling hills over the State. Flowers 



April 15. Fruit x\ugust. 

 New Orleans, March, 1921. 



THE FOREST FLORA OF THE OZARK REGION 



Ernest J. Palmer 



A GLANCE at a relief map of North America will serve to show the unique 

 and interesting position occupied by the Ozark uplift with relation to the 

 surrounding regions and the other great physiographic features of the 

 continent. Between the foot hills of the Appalachians on the east and 

 the Rocky Mountahis on the west extends a vast almost unbroken plain, 

 its surface conforming generally to the horizontal or gently tilted strata 

 that underh'e it, and modified only superficially by the forces of erosion, 

 glaciation and similar agencies. The only place at which these wide 

 spread rocky beds have been extensively disturbed by orogenic forces 

 and thrust up conspicuously above the surrounding areas is in the Ozark 

 region, situated approximately midway between the two great mountain 

 systems and between the Great Lakes and the Gulf of Mexico. It is 

 thus isolated and remote from both coast-line and other mountainous 

 areas, and is completely surrounded by wide, fertile plains, that have 

 for ages been the breeding groimds and battlefields of successive races 

 of plants and animals, many of which, we may safely assume, have from 

 time to time invaded the highlands or been forced to lake refuge there 

 from the pressure of aggressive competitors or ruthless enemies: For 

 geological evidence proves that the Ozark region is one of the oldest land 

 areas on the continent; and although portions of it have been subjected 

 to various uplifts and depressions before the beginning of the cycle that 

 gave it its present form, most of it has remained above sea level since very 

 early linies. 



To the south of it lies the low, humid plain of the Gulf coast, with its 

 rich forests of coniferous and deciduous trees, a region of deep swamps, 

 dense cane brakes and impenetrable tangles of vines and herbage, alter- 

 nating with low lulls, sandy ridges and broad savannas, formerly teeming 

 and still abounding in parts with a profusion of bird, reptile, mammal and 

 lower animal forms; on the east is the broad, fertile valley of the Miss- 



