Ikki(;ati()n Water 
15 
No. of samples in 
SjiecMes wliich occurred 
Verbena stricta — Hoary vervain (5 
Verbena bracteosa — Bracted vervain 34 
Verbena bipinnatifida — Bipinnate vervain j 
Veronica species — Speedwell I 
Avena sativa — Oats 41 
Secale cereale — Rye .. 
Andropogon sorghum — Amber cane ’ ] 
From the above table it will be seen that the weed seeds 
most frequently met with in the irrigation waters examined 
are: 
Prostrate pigweed (Amaronthus hlitoides). 
Tall pigweed (Amaranthus retroflexus). 
Sedge ( Cavpx s-p.). 
Lamb ’s quarters (Chenopodiwm alhmn). 
Tall marsh elder (Iva xantliifoUa). 
Door-weed (Polygonum aviculare). 
Black bindweed (Polygonum convolvulus) . 
Curled dock (Buimex crispus). 
Dandelion (Taraxacum officinale). 
TABLE II.— SHOWING THE ESTIMATED NUMBER OF SEEDS, OF A FEW 
REPRESENTATIVE SPECIES, WHICH PASSED A GIVEN POINT ON A 
12-FOOT DITCH DURING A PERIOD OF 24 HOURS 
Caught on 
Floating on 

3t4" surface 
12' surface 
Cross-section 
(’ross-section 
KIND OF SEED 
1.14 Sq. In. 
Time 
231.no Sq. In. 
Time 
Date 
Dandelion (Taraxacum offi- 
cinale) 
Lamb’s quarters (Chenopo- 
461 
15 min. 
1 0,355,904 
24 hrs. 
5/24/19 
dium album) 
Pigweed (Amaranthus retro- 
58 
15 miM. 
1,302,912 
2 4 hrs. 
5/24/19 
flexus) 
Wild buckwheat or field 
57 
15 min. 
1,280,448 
24 hrs. 
5/20/19 
bindweed (Polygonum con- 
volvulus) 
4 
15 min. 
8 9,856 
24 hrs. 
5/20/19 
Curled dock (Rumex cris- 
pus) 
6 
15 min. 
134 785 
5/24/19 
ms. 
Marsh elder (Iva xanthi- 
folia) 
Green foxtail (Setaria vi- 
7 
15 min. 
157,248 
24 hrs. 
5/22/19 
ridis) 
Sunflower, wild (Helianthus 
2 
15 min. 
44,928 
24 hrs. 
5/22/19 
petiolaris) 
2 
15 min. 
44,928 
24 hrs. 
5/24/19 
The examples cited in the above table do not represent the largest catch 
of any one species in a 15-minute period. 
