DEVELOPMENT OF SEED IN POLYGONACEAE 46 1 
Rumex 
In this genus, the two species studied, Rumex crispus and Rumex 
Acetosella, are essentially alike in their development, and follow to 
maturity the same plan as that described for Polygonum Persicaria. 
Some interesting differences from the type appear in the mature seeds. 
The embryo of R. crispus, in its development to maturity, comes to 
lie usually at one side of the seed {figs, ii, E, and 13, C) with the back 
of the outer cotyledon pressed against a flat surface of the seed and the 
chalazal region. The massive, somewhat flattened hyocotyl is the 
same width as the cotyledons which are semicircular in section. The 
mature seed is 2.45 mm. long and 1.55 mm. wide. 
In Rumex Acetosella the mature embryo {fig. 12, E) usually 
occupies the same relative position at one side of the seed as in R, 
crispus. The embryo is very much more curved, corresponding with 
the shorter and relatively broader seed, which is 1.2 mm. long and .9 
mm. wide. The cotyledons, similar in section to those of R. crispus 
{fig. 13, C), extend across the chalazal region almost to the angle 
opposite. 
The position of the embryo against a flat surface of the seed is 
apparently not a fixed character in Rumex, for the writer in examining 
a number of seeds of both the above species, found, in several cases, 
the embryo situated in an angle of the seed. This is a marked contrast 
to the conditions found in the genus Polygonum, for there the position 
of the embryo seems to be a fairly fixed character. 
Polygonella 
The single species studied, Polygonella articulata, showed some very 
marked differences from the selected type. Polygonum Persicaria, 
although some stages in the development correspond very closely. 
The early development up to the octant stage agrees with the type, 
except in the length and structure of the suspensor. At this stage, 
shown in figure 14, the suspensor, T, is about two thirds the length 
of the embryo sac, and is made up of large inflated cells. The lower 
two thirds consists of two rows of cells, while the upper micropylar 
portion is made up of a single chain of four or five cells. 
As development proceeds growth and nuclear division in the endo- 
sperm is uniform in the micropylar region, and about the periphery 
of the embryo sac. At about the time that the meristematic regions 
