io7 
relation to the Soils on which they grow . //. 
A number of species which were absent from seed crops in Bedfordshire 
frequently occurred in association with them in the West Country. This 
may partly be due to the fact that a large proportion of the clover and 
rye-grass crops had only recently been seeded, and had made little growth 
owing to the long drought. In consequence the weeds had not suffered so 
much from the overshadowing effect of the leafy crop. Under the circum- 
stances the occurrence of such weeds in conjunction with seed crops lends 
support to the hypothesis that their absence, when it occurs, is due to the 
starvation of light or air by the crop rather than to any inherent antagonism 
between the two plants, weed and crop. It is noticeable that the number 
of absentee species in the West Country records is only nine, as against 
twenty-one in the Bedfordshire lists. 
2. Couch or Twitch was frequently noted as a troublesome weed, but as 
a general rule only two species were designated as such, instead of the half- 
dozen met with in other places. 
(a) Triticum repens — the true Couch. 
(b) Arrhenatherum avenaceum var. tuberosum — the ‘ Onion Couch 
or ‘ Knotty Couch \ This is one of the worst of weeds when it occurs 
in any quantity, as it easily spreads and is most difficult to eradicate on 
account of its swollen tuberous stems, each joint of which will develop into 
an independent plant if detached. 
3. In one instance the most pestilent weed was Avena fatua or Wild 
Oat, which existed side by side with the ‘ Onion Couch ’. This weed is 
particularly troublesome, as 
(a) it spoils the crop ; 
(b) it spoils the sample of corn ; 
(c) it gets into the thrashing-machine parts and clings together by 
its hairs until it blocks every outlet. 
4. Equisetum and Coltsfoot did not occur in company so frequently as 
they did in Bedfordshire. The Coltsfoot was more often associated 
with clay soils, but as before the distribution of both weeds was general. 
It has been suggested that the presence of Coltsfoot is an indication of the 
nearness of underground water, and that the plants can only thrive if 
they can send down their long roots to tap it. This idea, however, needs 
confirmation. 
5. Two plants are totally different in their habitat in the two 
districts : 
(a) Bartsia Odontites , which is a clay weed and calcifuge in Bedford- 
shire, is practically absent from clay and is very frequent on chalk in the 
West. 
(b) Chenopodium album , which is never recorded from chalk in 
Bedfordshire, is noted more frequently from that habitat than from any 
other in the West. 
