390 SCIENTIFIC AND APPLIED PHARMACOGNOSY 



EUPHORBIACE^;, OR SPURGE FAMILY 



A large family of about 4000 species, which are very widely 

 distributed. Outside of the fact that the flowers are subtended 

 by an involucre, which resembles a calyx, and the fruit is a 3-lobed 

 capsule, there are no distinctive morphological features which 

 extend throughout all the members of this family. It is ordinarily 

 stated that the plants possess a milky acrid juice, but this is only 

 true of some of the genera. There are no less than 8 different kinds 

 of secretory tissues in this family. (1) Laticiferous Cells are espe- 

 cially characteristic of the Euphorbias. They occur in the pith, 

 cortex and in the veins of the leaves and the contents in the living 

 plants are generally milky and may contain starch grains, protein 

 crystals, rosette aggregates of calcium oxalate and tannin. (2) 

 Laticiferous Vessels occur in Hevea, one or more species of which 

 yield caoutchouc, and in Manihot, the tuberous roots of which fur- 

 nish tapioca starch. In the former the juice is of a milky character 

 and in the latter in the nature of a watery sap. (3) Rows of lati- 

 ciferous sacs are confined to the genus Micrandra. The cells form 

 long chains and contain a sap, which, on drying, is colored gray. 

 (4) Tanniferous Cells occur singly or in chains and have a brownish 

 content. They are widely distributed in the Euphorbiacese. (5) 

 A secretory organ, consisting of very much Elongated Sacs having a 

 brownish content, is found solely in the pith cells of Mallotus and 

 some other genera. They are usually surrounded by a ring of small 

 cells resembling an epithelium.' (6) Idioblasts, or secretory cells 

 with an oleo-resin content, are found in Ricinus, Croton, etc. The 

 cells are large and contain a yellowish and strongly refractive secre- 

 tion, giving rise to transparent dots in the leaves. (7) Secretory 

 Lacunae, resembling the intercellular secretory receptacles, occur in 

 some of the Leguminosa?. (8) Mucilage Lacunas or groups of cells 

 having mucilaginous walls, are found in a limited number of genera. 



The pericycle is of varied composition, being either without any 

 sclerenchyma or composed of a ring of mechanical tissues or in some 

 instances composed of isolated groups of bast fibers, in the latter 

 case the walls are lamellated. The tracheae usually are marked by 

 simple pores and scalariform perforations. In some instances, the 

 latter type only being developed. The tracheal walls, adjoining 

 parenchyma cells, may possess either simple or bordered pores. The 

 wood fibers have either thick, somewhat mucilaginous walls and nar- 

 row lumina, or thin walls and large lumina, the transverse walls being 

 occasionally septate. Calcium oxalate is usually secreted in the form 



