ON THE AFFINITIES OF CERTAIN ANOMALOUS 
DICOTYLEDONS. 
DOUGLAS HOUGHTON CAMPBELL. 
THERE is still a difference of opinion among botanists as to 
the relationship between the two great divisions of angio- 
spermous plants, monocotyledons and dicotyledons. The two 
groups have evidently been derived from a common stock, but 
which branch is the older is still somewhat doubtful. 
Among the genera commonly referred to the dicotyledons 
are several which differ from the typical forms both in the 
structure of the flowers and in the character of the tissues, 
especially the structure and distribution of the vascular bundles. 
Among these anomalous dicotyledons may be mentioned the 
Nymphaacez, certain Ranunculacez (Actaa, Thalictrum), 
and among the Berberidacez, Podophyllum, Diphylleia, and 
Caulophyllum. 
A recent paper! on the embryo of Nelumbo has called atten- 
tion to the importance of a thorough study of these anomalous 
genera, whose embryogeny is almost completely unknown. 
The result of Lyon's examination of Nelumbo was the dis- 
covery that the apparently dicotyledonous embryo has really 
but a single cotyledón and resembles that of the aquatic Alis- 
males, an order of monocotyledons that shows numerous analo- 
gies with the Nymphzacez. 
This interesting discovery suggested to the writer the advis- 
ability of looking up what had been already done with the 
. study of the embryos of some of the other forms referred to, 
and although the results of these inquiries have been very 
incomplete, they have revealed a number of “extremely sugges- 
tive facts, which are here given, and which emphasize the 
desirability of more thorough work in the same direction. 
1 Lyon, H. L. Minnesota Botanical Studies, Ser. 2, pt. v, 1901. 
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