STUDIES ON SOME ANOMALOUS DICOTYLEDONOUS 
PLANTS. 
CHARLEs E, Lewis. 5) 
(WITH PLATES VII AND VII!) 
HISTORICAL. 
SEVERAL genera commonly referred to the dicotyledons differ 
from the typical ones both in the structure of the flower and in 
the form and arrangement of the vascular bundles. Among 
these anomalous dicotyledons are certain Nymphaeaceae, Ranun- 
culaceae, and Berberidaceae, which have been referred to dicoty- 
ledons chiefly on account of the structure of the mature embryo. 
The striking resemblance of the Nymphaeceae to the Alis- 
males, which are typical monocotyledons, has led to the study 
of the development of the embryo in certain genera of the 
former in order to determine the origin of the structures found 
in the mature embryo. The first work of this kind was done by 
Lyon (1901), who investigated the development of the embryo 
of Nelumbo. He found that the two large fleshy bodies of the 
mature seed seemed to be lobes of a single cotyledon which has 
its origin as a crescentic ridge of tissue, partly surrounding the 
plumule and later bifurcating to form what appears as two 
a ee eee ee et ae ee A ey ae 
Sei Say ETE ee 
Bie as” 
cotyledons. 
Cook (1902) published the results of a study of the embryo 
sac and embryo of Nymphaea advena and Castalia odorata. He 
describes the embryo as monocotyledonous and agrees with Lyon 
that the Nymphaeaceae should be regarded as monocotyle- 
donous. 
In a paper which appeared a short time after that of Lyon, 
Campbell (1902) calls attention to the affinities of certain anom- 
alous dicotyledons. It is pointed out that the embryo of the 
mature seed and the seedlings of certain Ranunculaceae and 
Berberidaceae, as observed by Lubbock and Holm, show the 
petioles of the cotyledons grown together where the edges are 
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