POISONOUS AND INJURIOUS PLANTS 29 
blossom and mature seeds in late winter or early spring after which 
the plants die. 
DisrrisuTion AND Hapirar.—This species occurs more commonly 
in the drier areas of all the Virgin Islands. The plants thrive best in 
full sun but are shade tolerant. They are found in cultivated fields, 
along roadsides and ditchbanks, and in open pastures. The plants 
prefer a well-drained soil and are somewhat alkali tolerant. They 
are most conspicuous during the winter and early spring when in 
blossom and fruit. 
ToxiciTy AND Symptoms.—The stems, leaves, and roots of Crotalaria 
retusa contain the very toxic alkaloid monocrotaline (2). The plant 
is toxic to cattle, sheep, goats, horses, mules, chickens, and turkeys 
(61). Acute poisoning sometimes occurs in cattle and swine, though 
chronic poisoning is more common. In acute cases, cattle have loss 
of appetite, bloody feces, nasal discharge, diarrhea, general weakness, 
and yellow discoloration of the mucus membrane; death occurs in 5 
to 10 days. Nine pounds of the plant is enough to kill a 300-pound 
steer. Acutely poisoned hogs often die suddenly of gastric hemor- 
rhage; 6 or 8 seeds will kill a 50-pound pig in a week. In chronic 
poisoning, animals may die 2 to 9 months after eating the plant. 
Often no symptoms appear until 7 to 14 days before death. Hogs are 
unthrifty, weak, and occasionally anemic. Symptoms in sheep and 
goats are similar to those in cattle (67). Horses and mules show ex- 
treme listlessness, weakness, stumbling, and a profuse diarrhea (9). 
In the majority of cases, horses and mules appear sleepy and walk aim- 
lessly during the late stages (77). The chief symptoms shown by af- 
fected chickens include discolored combs, loss of appetite, and a sleepy, 
depressed appearance (43). 
MANAGEMENT AND ContTroy.—This species is a potential danger to 
livestock, since it is eaten in small amounts from the seedling stage 
through maturity. Denying livestock, especially horses, access to 
infested areas should be practiced because once symptoms are ap- 
parent, poisoned animals seldom recover. Destruction of the plants 
requires continuous or recurring treatment, as the seeds germinate 
sporadically over long periods. Manual control is recommended for 
sparse stands. Mechanical and chemical control measures are more 
economical where stands are abundant. Clipping pastures before the 
plants have seeded is often partially effective, but does not remove 
the entire plant. The most effective control measures are with herbi- 
cides, of which the ester forms of 2,4—-D and 2,4,5-T are known to be 
highly toxic. | 
Leguminosae, or Legume, Family 
Crotalaria verrucosa L. (fig. 15) 
_Descriprion.—This annual weed is 1 to 4 feet high and has angled, 
zigzag branches, which are sparsely covered with fine hairs. The 
simple leaves are borne alternately along the stem on short leaf stems; 
they are rounded at the apex and narrowed at the base. The thin 
leaf blades are nearly smooth above, sparingly hairy beneath, 2 to 3 
inches long and about 2 inches wide. The conspicuous rounded leaf- 
like structures, called stipules. borne at the base of the leaf stems, 
may reach 44 inch in length. The light-blue, pea-shaped flowers, about 
609308 O—62—__3 
