Evening star., 1953-08-03
Farmers May Cultivate
Crops of Rore Metals
Loco Weeds Found to Have
Valuable SeIenium Element
By Thomos R. Henry

Farmers eventually may be growing
crops Of gold, selenium and other rare
metals.
This is foreShadowed in a report to
the American Chemical Society here on
the use of loco weeds, the pea-like herbs
Of the Western plains which poison
cattle, as potential commercial source
Of Selenium.
The locoS, according to the report
in the society's Industrial and Engi-
neering Chemistry, collect this relatively
rare element from the surrounding soil
and concentrate it in their tissues. AS
much as is per cent selenium may be
concentrated in plant growing on a
soil that contains only five-thousands
Of one per cent.
Essential in Several Industries.
Seleniun. steel-gray element closely
related to sulphur. is essential In the
electronics, petroleum and rubber in
dustries. At present most of 1t is OBJ
tanned as bi-product of copper. More
than 100000 pounds are imported an
nually but the supply still is insufficient.
The major problem of growing Sc
lenium as farm crop is that of de-
viSing a method of cheap extraction
from the plant tissues. Chemists Of the
Battelle Memorial Institute of Colum-
bus now are at work on this.
Selenium Is not the only valuable
element found in plants, the report
points out. Potassium and iodine are
extracted commercially from sea weed.
The horsetail plant has been found to
contain as ounces of gold ton, or
600 times the gold content of the sur
rounding soil.
The ash of hickory trees may yield
as much as 81 per cent aluminium and
4 per cent manganese. Muskmelon
leaves and sweet clover collect boron.
Dandelions, spinach and tobacco store
copper, and some ragweeds contain
zinc. The uranium mineral
vanadium has been found in clover.
beans, beetS and pine needles.
Victims Doublecross Cowbird.
The cowbird's victims are learning to
double-crosS it.
The cowbird's notoriety came from
its practise of laying its eggs in the
nests Of other birds, thereby saving
itself the trouble of Matching them
and caring for the young.
The eggs are too heavy for the
owners Of the nests to move. In some
cases they may not be able to dis
criminate between them and their own
eggs. When the cowbirdS hatch they
are likely to crowd out of the nest the
dedglings of the rightful occupants.
This challenge has been met success
fully by the yellow warbler of American
woodlands. according to a report by
DR.. Arthur c. Bent. just issued by the
Smithsonian Institution. To lay its own
eggs it simply builds a second floor
over the nest in which the strange
egg has been deposited. It thus leaves
the alien egg to "cool off in the cellar"
Six-Story Nest Is Built.
"T'he yellow warbler" Mr.. Bent says,
"is not the only bird that has learned
to do this occasionally, but it is the
only one that does it regularly and
persiStently in spite of repeated con-
trlbutionS from the cowbird. Even II
the warbler has one of its own eggs
in the nest when the cowbirds egg
is deposited, it may bury both the eggs
by building story above them.
But the cowbird is very persistent
and keeps on laying, as successive
stories are added to the nest by the
perSevering and energetic warblers.
Two-story nests are very common and
as many as six stories have been re-
corded. In one case a six-story nest
was built with a cowbird's egg in
every one"
The yellow warbler is sometimes
known as the wild canary"