204 THE CORRESPONDENCE OF SCHWEINITZ AND TORREY 
tions & advice respecting that part of the work which yet remains 
to be printed. Descriptions or localities of new, rare or doubtful 
species will be most precious to me; and I may add, will make 
my book more valuable to others. 
I will here make some observations on a number of plants which 
will soon come in order for publication. Please answer my queries 
as far as you are able. 
1. Arenaria canadensis Pers. Is this more than a variety of A. 
rubra altered by its maritime situation? At any rate 
can it be distinct from A. maritima of Smith? 
How shall I distinguish the caulescent species of Oxalis? 
Surely Elliott has made too many species. The charac- 
ters of O. stricta & corniculata given in the books apply 
nearly as well to one as the other. 
Is the Cerastium glutinosum of Nuttall the C. longepeduncu- 
latum (!!) of Muhlenberg? 
. Is C. tenuifolium of Pursh distinct from C. arvense of Europe? 
. Can Lythrum verticillatum be a congener with L. hyssopi- 
folium & some Europ. specs. ? 
. What is the Euphorbia portulaccoides of Muhlenberg’s Cata- 
logue [52]? 
Is Talinum teretifolium as Mr. Rafinesque asserts, a peculiar 
genus? 
. What species of Prunus have you found in Pennsylvania? 
There are several mentioned by Pursh which I never saw. 
Indeed, I think he has made considerable confusion among 
many of the species. His P. depressa can scarcely be 
the straggling prostrate bush so common on Long Island 
& known by the name of sand cherries. 
Crataegus also puzzles me. I want your list of northern 
species, with your synonyms. C. elliptica & viridis I am 
curious to see. 
10. Sorbus microcarpa. Can you let me have a specimen of this? 
11. Pyrus ovalis. Is this a good species? 
Thus far I will go at this time, & as soon as I hear from you will 
furnish another list of such plants as I wish your opinion respecting. 
It is well your package for Dr. Hooker did not come a few days 
sooner for the vessel by which I sent some things was wrecked be- 
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