i88 
O. A. STEVENS 
to have come from Pierre, S. D. In this sample there were about 
300 Cuscuta seeds per ounce. A number of seed samples have in- 
dicated the presence of this species in alfalfa fields along the Missouri 
river in this state. Some search of such fields in 1914 and 1915 dis- 
closed only an occasional plant. The economic status of C. coryli 
is therefore open to further investigation. One plant in the garden 
produced about 7,000 seeds, although the species does not seem to 
produce as much seed as C. arvensis. The seeds are quite similar 
to those of C. indecora, plattensis, and gronovii. In cleaning the seed 
grown from the South Dakota sample it was found that about half 
of the Cuscuta could be screened from the alfalfa seed on account of 
the larger size of the former. The following measurements were 
made with a binocular microscope at 50 diameters. 
Size of seeds of Cuscuta 
Species 
Minimum 
Maximum 
Av. of 50 
.9 X .6 mm. 
1.2 X .8 mm. 
1. 00 X .73 mm. 
C. arvensis 
.9 X .9 
1.6 X 1.3 
1.33 X 1. 15 
C. coryli 
1.4 X 1.3 
2.6 X 2.1 
1.80 X 1.50 
C. gronovii 
1.4 X 1.4 
2.4 X 1.8 
1.90 X 1.60 
C. plattensis 
1.6 X 1.3 
2.5 X 2.1 
2.10 X 1.70 
From plots in the garden the germination of scattered Cuscuta 
seeds was observed as early as April 30, but little growth was made 
until the last of June and flowering began about the second week in 
August. Cuscuta coryli was killed by frost a little earlier than the 
C. arvensis in the same plot. 
Seed Laboratory, 
North Dakota Agricultural Experiment Station 
