NOTES ON. THE EUPHORBIAS .OF. DR. EDWARD 
PALMER’S DURANGO (MEXICO) COLLECTION 
OF 1896. 
CHARLES F. MILLSPAUGH. 
Tue following notes, based upon Dr. Edward Palmer’s 1896 
collection from the neighborhood of the city of Durango, Mex- 
ico, while offering but little in the line of novelties, will serve to 
emphasize the necessity of closer study into the relationship of 
species in the extensive and intricate genus Euphorbia. 
Upon continual comparison of the various species, I have 
become more than ever convinced that the general habit gives 
but little insight to true specific character, especially in the 
Anisophyllz, and that it is in the seeds only that absolute con- 
stancy of character exists. These seeds, minute as they are, 
retain their specific character even when the general characters 
of the plant become radically changed by the environment. In 
regard to the involucres, little can be determined by them 
except by careful and complete dissection and evisceration of 
the tubal envelope, the walls and appendages of which only then 
exhibit their true characters. It would appear that in the typ- 
ical Euphorbia there are five glands in alternation with five 
involucral lobes; thus wherever one or more glands are absent 
in a species some rudiment of these organs remains. This is 
indicated by the five heavier veins or bands of thickened tissue 
that lead up from the pedicel to these appendages. While the 
lobes of the involucre, that play so serious a part in the fructifi- 
cation of the ovule, are constant in their character, the glands 
and their rudiments, being accessories only, vary much with the 
habitat and environment of the individual. 
In any series of species the size variation is so great that no 
specific scale of drawing can be profitably maintained, nor would 
the invariable application of such scale be of practical value. 
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