494 SPURGE TRIBE; CASTOR-OIL, MANCHINEEL. 



is an Involucrum of bracts, something like that of the Compo- 

 site (. 629) ; the whole being thus a kind of head^ rather than 

 a single flower. In general the floral leaves are green, so that 

 the whole flower is almost destitute of colour ; but sometimes 

 they present most brilliant hues. 



670. In other genera of the order, the structure does not 

 depart so widely from the ordinary type. In some of them we 

 even find a double perianth, each whorl being usually made up 

 of five or six divisions. The stamens are extremely variable in 

 number; and the ovarium consists of three carpels (sometimes only 

 two) which separate from each other in ripening ; each of these 

 incloses one or two ovules. . A very good illustration of this struc- 

 ture is found in the Palma Christi, or Castor-oil Plant, which is 

 often cultivated in gardens, on account of the handsome appear- 

 ance of its leaves and clusters of flowers. Many of this order 

 are very succulent ; and several of the tropical species present 

 very much the appearance of the Cactese, being leafless, and 

 having their swollen stems beset with spines. Nearly all of this 

 tribe possess acrid properties in a greater or less degree ; but 

 these are most powerful in the roots of the larger species, which 

 are not of annual growth. In Africa and Asia, the leafless 

 thorny Euphorbias are often planted for fences ; and they serve 

 most effectually to keep out intruders, injuring those who 

 attempt to pass, not only by their sharp spines, but by the 

 acrid juices which they instil into the wounds made by these. 

 One of the most violent in its action of all the species of this 

 order, is the Manchineel tree of the West Indies ; the juice of 

 which, when applied to the skin, produces corroding ulcers. It 

 has been said that it is dangerous even to remain under the 

 shadow of the tree, but this is an exaggeration ; it has been 

 stated on good authority, however, that, if a person take refuge 

 under one of these trees from a shower of rain, the droppings 

 become charged with its exudations, and produce troublesome 

 sores on any part of the skin which they may touch. The juice 

 of this and of many other trees has been used to poison arrows. 



671. Although the juices of the leaves and stem are usually 

 so acrid, other parts of the plant may be applied to various uses. 



