IOWA ACADEMY OF SCIENCE 
129 
SOME POINTS ON THE FLORAL DEVELOPMENT OP RED CLOVER 
( TRI FOLIUM PR ATEN 8E). 
BY J. N. MARTIN. 
The approximate lengths 6f the different floral parts at the time the pollen 
mother cells are beginning to form pollen grains are as follows: Calyx, 1 mm.; 
corolla, % mm.; longer stamens, % mm.; shorter stamens, % mm.; pistil, 
% mm. 
The stamens do not develop simultaneously. Some anthers are in the pollen 
mother cell stage, while others are in the tetrad stage. The longer stamens 
are usually more advanced in development. The elongation of the filaments 
keeps pace with that of the style, so that the anthers maintain about the same 
relative position in refenence to the stigma throughout their development. 
The development of the pistil is much slov/er than that of the stamens. At 
the time the pollen grains are being formed, the ovules are very small, the 
integuments barely evident, and it is not until much later, that a megaspore 
mother cell appears. The style is characterized by a cavity which leads from 
the interior of the ovary up to the base of the stigma. 
The ovules arise from a cushion of tissue on the standard side of the ovary. 
Two ovules are present and both develop equally up to stage of fertilization. 
After fertilization, one ovule aborts and only one seed is present in the mature 
pod. 
The ovule is campylotropous and has two integuments. There are 3 rows 
of cells in the outer integument, 2 rows in the inner integument, and 5 in 
the nucellus. 
The nucellus is rapidly destroyed by the developing embryo sac, so that only 
about one-fourth of the nucellus remains at the time of fertilization. As this 
remnant is at the antipodal end, the embryo sac is in direct contact with the 
inner integument on the sides and at the micropylar end. 
Pistils self-pollinated and killed 16 hours afterward, show pollen tubes which 
have traversed more than one-fourth the length of the style, but none have 
been found to reach the embryo sac. 
A more detailed account is to follow. 
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