POISONOUS AND INJURIOUS PLANTS 85 
DIsTRIBUTION AND Haprrat.—Castorbeans are native to the Tropics. 
They are often planted as ornamentals, and are common weeds 
throughout the Virgin Islands; elsewhere they are planted as a field 
crop. Due to their copious seed production and adaptability, the plants 
have become scattered over wide areas. Escape plants appear in 
cultivated fields, along roadsides and ditches, in vegetable and flower 
gardens, and in provision and dumping grounds. The plants may be 
found growing singly, in small patches, or in thick stands. Castor- 
beans thrive best on rich, deep soils in full sunhight; however, they 
are shade tolerant. They occur more commonly in moist areas and 
are less common in drier areas. The seeds germinate where there is 
sufficient moisture and the plants grow rapidly. 
Toxiciry AND Symproms.—Castorbean contains the toxic material 
ricin, which is a true protein (60). Chick-feeding trials indicate that 
all parts of the plant are poisonous but that the seeds are the most 
poisonous. As few as 6 seeds have killed horses, and as few as 2 
have caused the death of children (79). The plant is toxic to all 
classes of livestock and to humans. The symptoms include nausea, 
vomiting, gastric pain, bloody diarrhea, thirst, hot skin, rapid pulse, 
sweat, and dullness of vision. Large doses may lead to death in 
convulsions or exhaustion. In the case of prolonged illness, muscu- 
lar tremors, general weakness, and emaciation occur. 
MANAGEMENT AND Controt.—Castorbeans occur in plentiful num- 
bers throughout the Virgin Islands. The plants occur in many places 
where they are accessible to livestock, and preventative measures are 
recommended. Although livestock do not browse on the plants ordi- 
narily, their presence constitutes a potential danger. Young castor- 
bean plants should be eradicated before they are allowed to mature 
seeds in order to prevent their increase and spread. Thick stands 
of castorbeans in widespread areas may be eradicated by cultivation 
or by use of herbicides. Cultivation kills small, young plants, but 
must be repeated frequently because it exposes buried seeds, which 
may sprout. Cutting the young plants at ground level usually kills 
them, but older plants form regrowth when cut. 
Poaceae, or Grass, Family 
Sorghum vulgare Pers. (Sorghum) (fig. 47) 
Sorghum sundanense (Piper) Stapf (Sudangrass) 
Description.—The many varieties of sorghum comprise a large 
group of coarse grasses with erect stems 2 to 15 feet in height with 
¢ to 18 joints. There may be several lateral shoots at the base. The 
long, narrow leaves occur alternately along the stem, one at each joint. 
The leaf blade gradually tapers to a sharp point at the tip; the base 
forms a sheath which clasps the stem between the joints. Varieties 
differ considerably in length and width of leaf. The leaves have 
prominent midribs and finely toothed margins. The small flowers 
are borne in terminal seed heads. The seed heads are 5 to 18 inches 
long and may be compact or spreading. The seeds of various sor- 
ghums differ in size, shape, and especially in color. Sorghums are 
divided into three classes according to usage: (A) Grain, (B) forage, 
and (C) combination grain-forage. Sweet and nonsweet types con- 
stitute another arbitrary but important classification. 
