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SURVIVAL ON LAND AND SEA 
grabbing plants at random. Testing unknown plants by small 
samples usually will reveal the harmless ones without causing 
serious injury. 
Widespread throughout most of the Tropics are the physic nut 
(Fig. 38) and the castor oil plant (Fig. 39). The seeds of both 
are poisonous to eat and cooking will not make them harmless . 
Strychnine comes from the seeds of an orange-like shrub (fig. 40) 
that grows in both the New and Old World tropics. The fruit 
may be eaten but not the seed. The fruit is so bitter, however, 
that you probably wouldn’t eat it even if you found it. 
Juices causing skin irritation are more common. Throughout 
Malaysia are the rengas trees (Fig. 41). They are avoided by 
the natives as carefully as we avoid poison ivy. The affliction 
produced by the sap of these trees is similar to that produced 
by poison ivy and the treatment for it is the same. A few of 
the, wild or semi-wild forms of mango also have poisonous sap, 
although the common mango does not, but the fruits from these 
trees can be eaten with safety. In the New World tropics the 
Mancineel or Manzanillo (Fig. 42), a small tree that occurs in 
dense thickets along sea beaches, is avoided for the same reason. 
The poisonous sandbox tree (Fig. 43) occurs at low altitudes 
throughout most of tropical America. It is a small tree with 
short, sharp grater-like spines and a melon-like fruit. A com- 
mon American plant with a poisonous milky sap is the Dumb 
Cane (Fig. 44) which is found in low ground and on moist hills. 
Its soft juicy stems are as large as a man’s arm and have a 
skunk-like odor when cut. Smoke and steam from the burning 
wood or leaves of any of these plants is dangerous and is as 
likely to affect the skin as the actual sap or juice. 
