POISONOUS AND INJURIOUS PLANTS 4] 
united most of their length but spreading at the top. A thick, light- 
green, leaflike structure in the form of a tube encloses the lower half 
of the flower. The round, nodding fruits are 1 to 2 inches in diameter 
and are covered with long prickles. The fruits dry and turn brown 
at maturity; they split into 4 sections to release many small, flat, 
shiny, black seeds. Pricklybur reproduces by seeds, and the plants 
die after producing a seed crop. The plants are most conspicuous 
during the wet season when they are in flower and fruit. Pricklybur 
ean be easily distinguished from jimsonweed by its color, the shape 
of its leaves, and its hanging fruits with longer prickles. 
DistrisutTion anpd Hasrrat.—Pricklybur occurs throughout the 
Virgin Islands. The plants are found in thick stands in cultivated 
fields. They also occur in waste grounds, along roads, fence rows, 
ditches, and in open pastures. It isa common weed in vegetable gar- 
dens and provision grounds. The plants thrive best in full sun and 
are seldom found growing in shade. They grow equally well over a 
wide range of rainfall belts on different soils. Although the plants 
are more abundant during the wet season, some can be found through- 
out the year. 
Toxiciry anp Symproms.—Because of their close relationship, 
pricklybur and jimsonweed have similar poisonous properties and 
affect animals similarly (7/8). (See Jimsonweed, Datura stramo- 
nium 1.) 
MANAGEMENT AND Controt.—Pricklybur is seldom eaten by brows- 
ing animals. Like many other toxic plants, it may be eaten when 
more desirable forage is unavailable. Preventative measures of deny- 
ing livestock access to the plant, particularly during the dry season, 
should be taken since livestock will feed on the plants only when hun- 
ery or confined to small areas. The plants therefore are a potential 
danger, and it is recommended that they not be allowed to grow in 
any accessible areas. Grubbing or cutting the plants by hand before 
they reach maturity is feasible for plants occurring in sparse stands 
insmall areas. For thick stands in large areas chemical control meas- 
ures are recommended. Mowing or bushcropping is an unsatisfactory 
method of control, as many plants will form regrowth. Selective 
herbicides, to which the plants are quite sensitive, may be used for 
control of large areas; repeated applications may be necessary to kill 
successive crops of seedlings. Ordinary cultivation practices will 
kill the plants when in the seedling stage. Care should be taken not 
to include the weed in silage. ; | 
Solanaceae, or Nightshade, Family 
Datura stramonium L. (fig. 22) 
Jimsonweed, Stinking weed 
Description.—This annual malodorous, coarse, woody weed is 2 to 
5 feet high with widespreading, ascending branches near the top of 
the stem. The plant is smooth throughout. The main stem and 
branches are light green, often covered with thin, white bloom or 
powder. The large, alternate leaves are light green and are borne on 
short, stout stems. The thin leaf blades are 3 to 8 inches long, 2 to 4 
inches wide, pointed at both ends, and have irregular shallow, sharp- 
