3 
regions or habitats where fire is a negligible factor of the environ- 
ment and are chiefly confined to fields, pastures, roadsides, etc. 
Of course a single fire sweeping a weedy roadside would not ex- 
terminate the weeds, but fires repeated every year on the same 
spot would be likely to prevent the reproduction of some, es- 
pecially annuals, and those with barbed or fleshy fruits. 
We have however a few weeds and other exotics which seem 
to be able to thrive in forests, either shady forests with abun- 
dant humus, or open forests frequently burned over. 
In and near New York City Prunus Avium, a European 
fruit tree, can be seen in many forests which appear almost prim- 
eval, or as nearly so as could be expected with such a dense popu- 
lation around them, and in such situations one sometimes has 
to look twice to distinguish it from Betula lenta, which is native 
in the same forests.* 
Ailanthus altissima (A. glandulosus), a coarse and usually 
crooked Asiatic tree with dry samara-like fruits, commonly cul- 
tivated for shade because it grows rapidly (though hardly any- 
thing else good can be said about it), often escapes to the woods 
around New York and farther south, though it is usually found 
in such unnatural habitats as not to deceive any one. However, 
on the north side of Bear Swamp, in Autauga County, Alabama, 
it grows tall and straight among native forest trees, in woods 
that have been altered a little by pasturing and the washing 
in of sand from the neighboring uplands.’ A botanist seeing it 
there in winter and not suspecting the presence of any exotic 
trees might have difficulty in identifying it. 
Melia Azedarach, the chinaberry, another Asiatic shade-tree 
common in the South (and westward to Mexico and California), 
often comes up from seeds dropped by birds along fences and 
around fields, and occasionally invades rich woods with native 
vegetation in the southeastern states, much as Prunus Avium 
does farther north. Almost the same could be said of Albizzia 
Julibrissin (commonly known as mimosa), another small Asiatic 
shade-tree, except that its seeds are in thin flat pods which are 
doubtless disseminated by the wind. 
Lagerstroemia Indica, the crepe myrtle, a small ornamental 
tree, likewise of Asiatic origin, is commonly cultivated in the 
uth, and may persist for many years after the house near 
ao 17: 135, 138, August, 1917. 
l. Surv. Ala. Monog. 9, p. 226, 1928. 
