K. W. Berry — Pleistocene Plants. 219 



Taxodium distichum (L.) Rich. Figs. 1, 2. 



Holmes, Jcmrn. Elisha Mitchell Soc, p. 92, 1885. 



Hollick, Md. Geol. Surv., Pliocene and Pleistocene, pp. 218, 237, pi. 68, 1906. 



Berry, Torreya, vol. vi, p. 89, 1906. 



Jonrn. Geol., vol. xv, p. 339, 1907. 



Amer. Nat., vol. xliii, pp. 432-434, f. 1, 2, 1909. 



This Jour. (4), vol. xxix, p. 391, 1910. 



Torreya, vol. x, p. 263, 1910. 



Plant World, vol. xvi, pp. 39-45, f. 1, 2, 1911. 



The deciduous twigs of the bald cypress, indistinguishable 

 from the existing species, are very abundant in the deposits. 

 This is an abundant species in the Pleistocene deposits of the 

 Atlantic coastal plain and it has been recorded from a large 

 number of localities distributed from New Jersey to Alabama. 

 The fact that several of these localities are north of, or inland 

 from, the present limits of distribution, together with abundant 

 sub-fossil evidence of restriction of range, indicates that the 

 species is slowly retreating southward as a result of gradual 

 and but little understood climatic change. None of the known 

 occurrences either recent or fossil are from an elevation as 

 high as this or as far removed from the ocean except where the 

 distribution has followed up river valleys like the Mississippi 

 and Ohio rivers as far as southern Indiana. The Blue Ridge 

 in central Virginia is about 150 miles in an air line from the 

 Atlantic ocean, with an average elevation of perhaps 2,000 

 feet, while numerous knobs are considerably higher. The 

 climatological station nearest Buena Vista is at Staunton about 

 35 miles to the northeast, where the elevation and topography 

 are similar.* As regards temperatures the annual mean is 

 55° with absolute maximum of 103° and absolute minimum of 

 — 13° and mean maximum of 66° and mean minimum of 44.° 

 The growing season extends from about April 15 to October 22 

 and the mean annual rainfall is 39*7 inches (spring mean 10*6, 

 summer mean ll - 6, fall mean 94, w T inter mean 8 - 4). 



A rough estimate of the climatic requirements deduced from 

 the present distribution of the bald cypress shows that the 

 mean annual temperature of its habitat ranges from 55° in 

 southern Delaware to between 65° and 70° , in Georgia, 

 Alabama, Louisiana and eastern Texas. The precipitation 

 varies from 40 to 60 inches per annum and is between 45 and 

 55 inches over a large part of the area. Hence it may be in- 

 ferred that optimum conditions for the Cypress are furnished 

 by somewhat higher temperatures and more abundant rainfall 

 than obtain at the present time in the Shenandoah valley. 

 Other undoubted factors of importance are humidity and 

 ground water level, data for which are not available. It seems 

 evident, however, that present conditions in the Shenandoah 

 * IT. S. Weather Bureau, Bull. Q, p. 255. 



