The evening times., 1900-03-15
No. 623 18th St. w.
BAD EFFECTS OF weeds
An Expert Talks on Their Accumu-
laiiOn on City Lots.
Useful in Absorbing Poisonous Gases
Until They Begin to Decay-Rank
Vegetation tnheaIthful-its De-
structiOn should He Accomplish
ed Under Municipal Direction.

Lyster H. Dewey, Assistant Botanist in
the Department of Agriculture, has made
a special study OF weeds in cities and
towns. and furnishes some interesting OBJ
servations on this subject.
In all cities and villages there are va
cant lots awaiting purchasers" he says,
"and in many agricultural districts the
unused land in towns often exceeds n pro-
portion the unused land In the surround
ing farms These vacant lots are held in
expectation that they will he used some
time for building sites. and until build
ings are erected upon them they are usu-
ally given up 10 whatever will grow. While
unused land in the country Is generally
covered with native yegetst tiop that in
cities and towns has usually az some time
been under cultivation. so that the native
vegetation has been destroyed, and its sit
uation is such that il is most readily seed
ing with migratory weeds. The seeds are
introduced in the packing OF rFo1kery. he
sweepings from stores. rubbish frem yards
cleanings from stables and stock cars, and
in various kinds of garbage and refuse too
commonly deposited on vacant lots.k I ne
conditions for weed produetion. have. been
most admirably prepared. and the natural
result is a plentiful crop.
In commenting on the ehara eteri5tics of
city weeds Mr.. Dewey said:
The weeds of cities and villages are
usually of the migratory CLASS, ,cosmopoli
tan in character, and capable of thriving
under a wide range of environment Ac-
cording to the early European works On
botany. plants from Asia, adventiye in Eu-
rope. usually appeared first in cities. Many
of these plants are now found about the
cities and towns of this country. Others
are native plants which have withstooi
the changed conditions due TO cultivation
and have acquired weed-like habit. In
the Eastern cities and in those on the Pa
cifc Coast Old World species predominate
while in the cities of the interior. espe-
cially in those west of the Missi -spIi
River. there is a larger proportion of na-
tive plants. The species vary in different
cities iE different years and in different
seasons.
The wild onion of winter and early
spring in this city is followed by the dan
delion and bubous buttercup; then come
the wild carrot, prickly lettuce and swee.
clover, and these in turn are partly dis
placed in the fall by hon seweed, ragweeI.
cccklebuT Mexican tea, slender pigweed
and jimson weed, chicory. horse cooke
burr, wild heliotrope, milk thistle. a-d tar
weeds
Mr.. Dewey spoke of the uses of weeds in
cities. as follows:
THE weeds growing within easy reach
of pupils and teachers in city schools fur
nish some material for botanical studies
Birds find in weed seeds a considerable
portion of their food supply. and some
times make their nests in the larger
weeds: but cockleburs, burdock thistles,
ragweeds and other coarse species might
well be replaced by seed-bearing grasses
and clovers which are better liked by
seed-eating birds.
Growing weeds. like other plants. pu-
rify the air. and herein lies the chief ben
eft conferred by their presence in cities
where numerous fires in dwellings, facto-
ries. and locomotives, and the breathing
Of the people continually rob the air of its
oxygen and charge it with carbonic -acid
gas. Growing plants. weeds as well as
others reverse this process. They with
draw from the air carbonic-acid gas and
sometimes other injurious gases, and give
off oxygen, thus tending to purify the air
and keep it supplied With the most essen
tial element.
Mr.. Dewey next spoke OF The bad ef-
fects of weeds which. he said, were but
little known.
THE injuries resulting from the pres
ence of weeds outweigh many times all
the good that can be ascribed to them" he
remarked. They harbor injurious insects
and fungous aud bacterial diseases of cul-
tivated plants. Many insects injurious to
garden and field crops also live on weeds,
upon which they thrive and multiply and
thus keep up their numbers ready to at
tack their favorite cultivated crop as soon
as it is left unprotected. The control of
insect enemies and fungous and bacterial
diseases of field and garden crops is rem
dered much more difficult and their exter-
mination, in some instances, is made prac
tically impossible, because they exist on
weeds that are not s$bject to the care be-
slowed or cultivateS crops.
While weeds are growing they aid in
purifying the air, but when growth stops
and they begin to decay their effect is just
the opposite. They then absorb oxygen