180 
to the commonly known one on the serpentine ranges of Chester 
County, Pennsylvania. 
1. Dunn’s Mt. and Roan Mountain, N.C. (Small.) 
2. Sapulpa, Indian Terr. (B. F. Bush.) 
3. Summit, Yonah Mt., Ga. (T. C. Porter.) 
4. Sandy Barren, Oquaka, Ill. 
5. Arena, Wisconsin. 
6. Little-Stone Mt., De Kalb Co., Ga. 
7. Rocky Knob, Caldwell Co., N. C. 
The following observation by Mr. E. J. Hillis to the point.* 
Talinum teretifolium was found in 1832 on rocks above Taylor's 
Falls. “It is occasionally met with from Pennsylvania westward 
to Minnesota in our northern flora, being more common in Min- 
nesota than elsewhere in this range of States.” It has also been 
found at Miller’s, Lake County, Indiana. In Illinois, it is found 
in sandy prairies and barrens. This disconnected distribution in 
isolated patches of country is hard to explain, unless we accept 
two propositions, both of which, or either of which may suffice as 
an explanation. 1. That its distribution as a species is due to the 
lightness of its seeds. 2. That being at one time a wide spread 
plant, it has been destroyed over the greater part of its range with 
the exception of a few localities, where it is still pretty abundant. 
It is important also to draw attention to the distribution of the 
plant as influenced by the soil or rock formations. It is found 
abundantly in some places on the serpentine outcrops in Chester 
County, where I. have observed its growth. These serpentine 
outcrops trend in a general southwesterly direction through 
Delaware and Chester counties, reaching their greatest extent in 
Pennsylvania on the Maryland line. These serpentine outcrops 
are essentially rocky oases, which have in some respects a peculiar 
flora. These barrens are characterized by the presence of the Red 
Cedar, Juniperus Virginiana, which, although scattered elsewhere - 
in the neighborhood, is never so abundant, nor so closely grouped, 
as on these stony places. Not all of the serpentine barrens have 
the same association of species, for instance, Cerastinm oblongifolium 
and Zalinum teretifolium are not found on all of the serpentine 
ledges, but are localized to particular ones. So it is with other 
* 1891. E. J. Hill, Botan. Gaz.16 : 112, Notes on Flora of St. Croix Region. 
