202 Rhodora [September 



A minor point in his discussion may as well be disposed of first. 

 Assuming that the plants at the top of the railroad cut nearest the 

 crock arc indigenous, it probably matters little whether the soil of the 

 neighboring embankment where they grow more luxuriantly came from 

 that cut or a thousand miles away, for the seeds are just as likely to 

 have been transported to that spot by birds or other animals as in the 

 ears that hauled the earth many years ago. 



Mr. Long did not seem to grasp the significance of the location of 

 his plants with reference to the creek swamp. The typical pine- 

 barrens of New Jersey, as is well known, are burned over every few 

 years; but the edge of a swamp, being protected on one side, is less 

 subject to fire, especially on the side away from the main both/ of pinc- 

 barreru, as in the present instance; and a gravelly embankment in a 

 swamp ought to be almost wholly exempt from fire. 



Plants not provided with thick bark or subterranean stems cannot 

 endure frequent fires, and no species of Prunna (including the sections 

 or subgenera Padvs, Ccraxus, etc.), in eastern North America at least, 

 seems to be very well protected in either of these ways. Of those the 

 writer is acquainted with, P. aerotina, P. unibeUata, P. Americana, P. 

 Carol iniana and P. sphaerocarpa grow mostly in rich woods, where 

 there is too little undergrowth to make much of a blaze. P. antjusti- 

 fo/ia is a weed of old fields and fence-rows, and P. scroti na is found in 

 such situations about as often as in natural habitats. P. Pennsyl- 

 raniea is one of the characteristic "fireweeds," that spring up in the 

 intervals between fire in the northern coniferous forests, and P. pumila 

 and P. maritima prefer sandy and rocky shores, where the vegetation 

 is too sparse to carry fire and the water affords protection on one side. 

 P. Besseyi grows in the barrenest places on the sand-hills of Nebraska. 

 and neighboring states, where the vegetation is sparsest, 1 and P. 

 t/cniculata on high sandy hills in the lake region of central Florida, 

 where fire is less frequent than in the more grassy typical pine-barrens. 2 



Possibly some reader may recall seeing some species of Prunus 

 touched by fire and not killed ; but a few exceptions will not materially 

 affect the truth of the assertion now made that fire, whether of natural 

 or artificial origin, is much less frequent in the habitats affected by 



1 See Pool, Minn. But. Stud. 4: 230, 23(>, 239. 1914; and review in Hull. Am. (JeoK- Sor. 47: 

 873-874. 191"). The writer made the arqiiainlanee of this shrub in northeastern Colorado 

 afler thai re\iew was written. 



2 See Torreya 11: <14-(i7. 1911. 



