380 
AMERICAN AGRICULTURIST. 
[October, 
The Animal Poison of the Far West — 
“ Loco ” or “ Crazy-Yv eed." 
BY PROP. ASA GRAY. 
[For several years there have been vague reports 
concerning the poisoning of domestic animals by 
some plant or plants in the far West, but we had 
been unable to learn anything positive concerning 
it. When Doct. Gray started last year with Sir 
Joseph D. Hooker to explore portions of the Rocky 
touching anything else, and these horses were 
affected as described in my first letter. Although 
there is great difference of opinion in regard to 
another weed that we have, which seems to be 
fatal to cattle only, all stockmen agree that ‘ Loco ’ 
is the weed that affects our horses. There are very 
few mules in my immediate neighborhood, and I 
have never known any to be injured by it, but oxen 
and cows are affected the same as horses. But I 
do not think they eat it as readily as horses, for we 
have very few injured by it, whereas I have known 
of an entire herd of horses being injured more or 
less by it. We have no hogs, except what are 
kept up. I do not think sheep are injured by it. I 
and commence again when the first snow falls. 
Animals are injured by it, I think, regardless of 
color. Here, where I live, at the foot of the moun¬ 
tains, the plant is common everywhere. 1 have 
none in my pastures, having taken the precaution 
to dig it up, but I understand from others that 
when cut and dried with hay it is not injurious.” 
The plants pointed out to us in both regions, 
or sent for naming, have all been of the Leguminous 
family, and of the Astragalus tribe.* The species 
to which this damage is attributed in the plains of 
Colorado, proves to be the Astragalus mollissimus 
of Torrcy—a very downy species, as its name indi- 
the “loco 
op the far west.— (Astragalus mollissimus.) 
cates—and to show what it 
is like we have here given a 
figure of it. We never found 
this species on the moun¬ 
tains. But there the same 
ill effects are charged upon 
plants of similar appearance, 
belonging to a nearly related 
genus, Oxytropis, mainly to 
0. Lambetti, which abounds 
at all elevations up to 8,000 
or 9,000 feet. The botanical 
difference between these 
plants is so little that they 
might all be counted as 
species of Astragalus; but 
there is reason to think that 
this particular Astragalus of 
the plains of Southern Colo¬ 
rado is much the most 
dangerous. For this species 
is not found as far north as 
Wyoming and Nebraska, 
where the Oxytropis abounds 
on the plains ; and there we 
never heard of this trouble. 
There was a prevalent no¬ 
tion that plants of the Pea 
tribe (Papilionaceousplants) 
generally are innocent, if not 
wholesome. No one sus¬ 
pected a tribe which gave us 
peas, beans, lentils, and the 
ubiquitous pea-nut, and sup¬ 
plies such fodder as does 
Clover, Medick, Lucern, 
Vetch, and Cow-pea. In the 
first edition of his “ Natural 
System,” Lindley wrote: 
“The general character of 
this tribe is its nutritious, 
or at least, wholesome pro¬ 
perties.” Later, the note is 
changed, and in the “ Vege¬ 
table Kingdom” he declares 
of the order, “that upon the 
whole it must be considered 
poisonous, and that - those 
species which are used for 
food by man or animals, are 
exceptions to the general 
rule ; the deleterious juices 
not being in such instances 
sufficiently concentrated to 
prove injurious.” What a 
pity that our cattle are not 
better acquainted with the 
corrected rule ! In Europe, 
and in the Atlantic States, 
no harm is known to come 
to cattle from want of 
proper discrimination. But 
when European flocks were taken to Australia, 
and to pasture and forage almost wholly new, 
thousands of sheep perished in the Swan River 
Mountains and California, 
we directed his attention to 
these reports, and asked him 
to endeavor to ascertain 
something definite concern¬ 
ing the trouble and the plant 
causing it, but his journey 
w’as made too late in the 
season for him to learn much 
concerning it. Since then 
letters and specimens have 
come from those having a 
personal knowledge of the 
injury to animals; these 
were placed in Doct. Gray’s 
hands, who in the follow¬ 
ing article sums up the 
present botanical knowl¬ 
edge on the subject.— Ed.] 
The papers for several 
years have abounded with 
accounts of a deadly Rattle- 
v : ced, and of the havoc it 
makes of sheep and goats, as 
well as other cattle, in the 
southern parts of California. 
The following are examples 
of the letters we receive in 
respect to this notorious 
cattle-poisoner of Colorado. 
Early in May specimens 
of the plant came through 
the kinduess of a friend 
from a drug firm in Hut¬ 
chinson, Kas., who wrote: 
“We send a sample of a 
plant called by Mexicans 
and Spaniards ‘Loco,’ and 
by our stock dealers, ‘ Mad- 
weed,’ ‘ Crazy Plant,’ etc. 
It is death to cattle, sheep, 
and horses, and seems to be 
known only in a strip of 
country from Indian Nation, 
westward to California. The 
peculiar influence on stock 
is manifested by making 
them ‘ crazy.’ They have 
dullness of vision, thirst, 
dizziness, and finally coma 
and death. Some of our 
stock dealers have lost as 
many as ten horses this 
spring from its effects.” 
In the following June, 
specimens were sent to 
the Editor of the Amer¬ 
ican Agriculturist by F. T. 
Brooke, Esq., of Huerfano 
Co., Col., who wrote: 
“ When eaten by stock it 
renders them perfectly 
crazy. It is called by the 
Mexicans ‘Loco’ or ‘Crazy- 
weed.’ A few mouthfuls will 
not affect an animal, but he 
soon becomes attached to it 
as a man does to whiskey, and will eat nothing else. 
The animals eating it are affected differently: some 
become perfectly wild, refuse to be ridden or 
worked, while others become listless, stupid, and 
unfit for anything. Some pine away and die ; others 
live on year after year, but are utterly worthless, un¬ 
less stabled and allowed nothing but hay and grain ; 
under such treatment some recover entirely, but 
are apt to commence eating the weed again if 
turned out to graze.” 
In order to obtain all the facts possible, the 
Editor addressed to Mr. Brooke a series of ques¬ 
tions, to which the following came in response, 
and will indicate the character of the questions: 
“ To the best of my knowledge and belief, the 
‘ Loco ’ is the plant that does the damage. I have 
6eeu horses eating this weed by the hour, without 
don’t know that they ever eat it; I have seen them 
in the midst of it, and could not see that any of it 
had been eaten. I do not think it affects the 
bowels or urine. I have heard (but won’t vouch 
for the truth of it) that the brain of horses dying 
from eating the weed, is entirely destroyed. Hence 
a legend among some of the cow-boys, that it is a 
worm in the "weed that finds it way from the 
stomach to the brain which it eats up. I know of 
no eases where horses died immediately from eat¬ 
ing it. I do not think, as a rule, that it is fatal. It 
is supposed to be equally active at all seasons, but 
I think horses acquire a taste for it in the spring ; 
it is one of the first green things they can get, and 
they eat it in preference to the old grass. If kept 
up until the grass gets a good start, they scarcely 
ever touch the weed. I have never had any horses 
affected by it, as I feed hay and grain until June, 
* But Mr. Sereno Watson, when in Utah, was shown a 
“Crazy-grass,” growing along the banks of the Jordan, 
which was said to craze horses that fed on it. The grass 
was Phalaris arunclinacea. the Reed Canary Grass, which 
has always passed for good fodder, and was never known 
to affect the intellects of horses or cattle in other parts 
of the country or in Europe. Probably the grass got the 
bad reputation, but some Astragalus did the deed. But 
there are “ Crazy Grasses,” one in S. Africa, one in 
Mongolia. Even the most reputable families—and the 
Grass family is at the top of the list—may have some dis¬ 
reputable members, like the “ Drunk Grass ” of S. Africa. 
