IOWA ACADEMY OF SCIENCE 
29 
PERCENTAGES BY MONTHS AND YEARS. 
Name of Weed 
Nov. 
Dec. 
Jan. 
March 
April 
April is ^ 
Subject- 
ed to 
Freez- 
ing 
1905 1 
1906 
o 
05 
1908 1 
iO 
O 
CO 
o 
o 
05 
00 
o 
s 
O 
05 
1 9061 
1907 
1908 
§ 
05 
1906 
1907 
00 
0 
'S 
10 
§ 
CO 
05 
c- 
0 
05 
00 
0 
05 
1905 1 
1906 
0 
05 
00 
0 
05 
Amarantlius retroflexus 
32 
6 
12 
0 
38 
10 
2 
2 
4 
12 
0 
0 
6 
26 
4 
12 
28 
10 
0 
26 
22 
62 
30 
Bidens' frondosa 
8 
4 
-4 
0 
2 
0 
6 
0 
0 
2 
0 
0 
0 
0 
8 
'0 
0 
6 
0 
2 
86 
68 
2 
Datura stramonium 
0 
22 
100 
__ 
0 
50 
70 
__ 
0 
32 
20 
__ 
0 
22 
40 
0 
26 
46 
__ 
28 
70 
__ 
■Rplpninm fintninnnlp 
2 
0 
6 
0 
6 
0 
0 
4 
4 
Lepidium apetalum 
32 
14 
22 
32 
64 
24 
40 
56 
2' 
28 
94 
54 
94 
58 
0 
86 
32 
Pnstinnpn satiysi 
2 
30 
16 
10 
68 
20 
6 
0! 
8 
8 
52 
20 
72 
32 
14 
48 
92 
98 
Setaria viridis 
42 
14 
10 
0 
66 
34 
0^ 
18 
28 
2 
'e 
50 
0 
8 
82 
70 
4 
0 
38 
66 
6 
0 
Sonchus oleraceus 
52 
2 
2 
— 
42 
26 
'e 
— 
— 
2 
;1 
— 
-- 
0 
2 
— 
8 
6 
2 
— 
” 
38 
8 
" 
The results of these tests seem to indicate the uncertainty with refer- 
ence to the germination of these various specis of plants. It has been 
shown by Dr. BeaT® that certain seeds when buried soon lose their 
vitality. This was true of Bromus secaliniis and DuveF has shown this 
to be true also for some seeds studied by him. The average germination 
in buried seeds was as follows: Original tests, 63.2 per cetit; control in 
chamber, 57.5 per cent; control in greenhouse, 53.2 per cent; buried 6-8 
inches, 20.5 per cent; buried 18-22 inches 26.5 per cent; buried 36-42 
inches, 31 per cent. This writer also indicates that there was a con- 
siderable loss in the vitality of seeds with hard coats like Lespedeza and 
Medicago. For instance, in the case of red clover, seed harvested in 
the same year was planted in 1902, germinated 2. 4, and 4 per cent for 
the three different depths of 6-8, 18-22 and 36-42 inches'. The hard seed 
in the clover remained over in the soil. He concludes that the seeds 
of cultivated plants with but few exceptions lose their vitality when 
buried in the soil. That seeds of the plants commonly designated as 
weeds retain their vitality remarkably well when buried in the soil. 
Wiesneff'^ states that the seeds of Pontederia crassipes, Mayacca fliivi- 
atilis, Heteranthera will germinate in water if previously dried out in 
the air, according to F. Muller^^ and according to Bohm^^ Pkaseolus 
midtiflorus will not germinate in the absence of lime salts. 
2«Bull. Mich. Agrl. Col. 5:1884. 
^The Vitality of Buried Seeds, Bull. B. P. I. U. S. Dept, of Agrl. 83. 
^“Biol. der Pflanz. 45. 
^^Cosmos. 7:183. 
^-Sitzungab. d. Kais. Akad. d. Wis. Wien. 71. 
See also Stohman Ann. d. Chem. u. Pharm. 1862. 121:319. 
