28 
IOWA ACADEMY OF SCIENCE 
nection. The germination of a few typical illustrations may be brought 
together in the following table. 
PERCENTAGE OF SEEDS GERMINATED BY MONTHS. 
Name of Weed 
Nov. 
Dec. 
Jan. 
Feb. 
Mch. 
April 
Fr’z’n 
April 
1. 
Abutilon Theophrasti 
9. 
37.3 
11.3 
28.6 
27.7 
37.3 
36. 
2. 
Amaranthus graecizans 
9.3 
2.6 
1 .66 
0 
1 10. 
7.3 
32. 
3. 
Ambrosia artemisisefolia 
9.2 
8. 
I 8. 
7. 
7. 
26. 
21.5 
4. 
Arctium Lappa 
10. 
6. 
1 1.5 
1.33 
2. 
‘ 2.6 
.42 
5. 
Apocynum cannabinum 
54. 
12.25 
! 4. 
2. 
46. 
54. 
6. 
7. 
Brassica arvensis 
*Cicuta maculata 
25.5 
39. 
34. 
33. 
19. 
52. 
44. 
8. 
Cassia Chamsecrista 
, 16.3 
13.6 
15.3 
3. 
i 2. 
8.6 
CO 
CO 
9. 
Chenopodium album 
22.6 
20.6 
2.6 
19 .‘3 
! 15.3 
1 3- 
44.6 
10. 
Cirsium lanceolatum 
1 14. 
13.3 
9. 
1. 
1 20.6 
16. 
34.6 
11. 
Echinochloa crusgalli 
4.6 
17. 
4. 
3. 
1 8.5 
! 13.6 
57. 
12. 
Lactuca Canadensis 
0 
2.6 
.50 
7. 
2. 
2. 
39.3 
13. 
Melilotus alba 
2.5 
4. 
2.6 
6.6 i 
2.5 
6. 
11.3 
14. 
Plantago major 
4. 
9.5 
.50 
1.3 
1.5 
5.5 
32. 
15. 
Polygonum pennsylvanicum . . 
3. 
5.5 
8.5 
0 i 
1. 
0 
45. 
16. 
Panicum capillare 
4.5 
8.6 
2.6 
1. 
8.5 
28. 
17. 
Rumex crispus 
15.3 
18.5 
1.5 
12. 
15.4 
12. 
36. 
18. 
Setaria glauca 
5.5 
10. 
7 .5 
.66 
50.5 
32. 
35.7 
19. 
Verbena urticsefolia 
5.5 
5. 
i 
± . 
.66 
4.5 
5.3 
31.5 
The foregoing table further illustrates the differences caused by freez- 
ing in the germination of weed seeds; for in the most cases, the germi- 
nation was greater after the seeds had been subjected to thawing and 
freezing than when kept in packages in a dry room. Of the November 
planting, November, 1908, of a total number of 65 species, four species 
failed to germinate ; of 60 species in December, 48 ; of 63 species in 
January, 44; of 62 species in March, 27; of 59 species in April, 46; of 
the seeds exposed to the weather, 64 species, 24 failed to germinate. 
The seeds of many of the weeds germinate in a very irregular man- 
ner. A few may be given to illustrate this : 
*No results. 
