FAMILIES OF FLOWERING PLANTS. 83 
dry and winged (called a samara) and in other genera, either a drupe 
(stone-fruit) or nut. 
Family Moraceae. Mulberry Family. Contains about 55 genera 
and nearly 1000 species, natives largely of tropical regions. 600 
species belong to the single genus Ficus, the fig, which is of immense 
economic importance, as it is the chief source of caoutchouec and 
furnishes us also with deli- 
cious fruits. Strictly speak- 
ing, the part which is eaten 
is not the fruit, but the pulpy 
receptacle, in which are em- 
bedded: the numerous small 
dry achenes commonly known 
as seeds. A similar condition 
exists in Morus, the mul- 
berry; the claims of , this 
tree to economic considera- 
tion lie chiefly in the fact 
that it is the best food for 
silkworms. The Moraceae 
are distinguished from the 
preceding family by the 
structure of their fruit, and 
by the presence of a milky 
sap. Among the genera of 
interest may be mentioned 
Artocarpus, the breadfruit, 
which is an important item 
in the dietary of the natives 
where it grows; Brosimum, 
the ‘‘cow-tree’’ of Venezuela, 
the sap of which furnishes a 
pleasant drink; Humulus, the. common hop; Broussonetia, the paper 
mulberry, an ornamental tree which has become naturalized in the 
eastern United States; and Cannabis, the hemp. 
Family Urticaceae. Nettle Family. Contains about 40 genera 
and nearly 500 species, very widely distributed. The majority are 
herbs, many of them provided with painfully stinging hairs. The sap 
is watery, and not of milky consistency, while the fruit is an achene. 
Fic. 68.—The Hemp Plant, Cannabis sativa. After 
Dodge, Rept. No. 9, U. S. Dept. of Agric. 
