226 Rhodora [NOVEMBER 
most pestilent to be found in New England fields and gardens. Promi- 
nent among these are couch grass, Agropyron repens, green foxtail, 
Setaria viridis, common sorrel, Rumex Acetosella, pigweed, Cheno- 
podium album, rough pigweed, Amaranthus retroflexus, and lady’s 
sorrel, Oxalis corniculata. The Agropyron roots deeply and can always 
secure water, even from rather dry soils, through its wide-ranging, 
many-rooted rhizomes. The Rumex has an exceedingly extensive 
and intricate root system. It is not so easy to explain why the other 
four species named in this group seem to be so little affected by the 
presence, or absence of an abundant water supply. 
The only weeds which have seemed to me relatively less important 
this season than usual are carpet weed, Mollugo verticillata and purs- 
lane, Portulaca oleracea. Both are xerophytes, as is evident from the 
way in which they tolerate extreme drought conditions, the former 
growing on very dry sand dunes, the latter a common weed in some 
of the driest parts of eastern Kansas and capable in ordinary climates 
of growing long after it has been uprooted and left lying on the surface 
of the soil. The seeds of purslane, according to Professor G. E. Stone 
of the Massachusetts Agricultural college, are exceptional in their 
power to grow in very dry soil, germinating in earth containing only 
0.5 per cent of moisture. It would not be easy to show marked 
xerophytic features in the form or the structure of Mollugo, but P. 
oleracea is decidedly succulent and is the most familiar plant of this 
type throughout a large portion of the central and the northeastern 
states. 
Doubtless other observers may in many cases have found different 
weed species predominant this year from those that have come under 
my own notice. Professor M. A. Chrysler of the University of Maine, 
at Orono, Maine, reports the July rainfall this year as 6.67 inches, 
while the average rainfall for the month is 3.22 inches. He does not 
report any weeds as having been unusually common. Mr. H. E. 
Downer reports from the botanic garden of Smith College, at North- 
ampton Mass., that almost all weeds are more troublesome than usual 
this season and names Digitaria sanguinalis, Mollugo verticillata, 
Portulaca oleracea, Oxalis corniculata, Acalypha virginica, Convolvulus 
arvensis, and Ambrosia artemisiifolia as particularly abundant. 
Weeds of lawns and grass lands, as a rule, have shown less response 
to the stimulus of an unusual rainfall than have many of the denizens 
of tilled ground. This may be partly because the grasses among 
