90 FAMILIES OF FLOWERING PLANTS. 
Family Aristolochiaceae. Birthwort Family. Contains 5 genera 
and about 200 species, of which 180 belong to Aristolochia alone. 
The family may be known by the tubular calyx, more or less inflated 
below, and adherent to the ovary at the base. The stamens are six, 
adherent to the style (colummar portion of the pistil), while the fruit 
is a many-seeded, 6-celled capsule. The plants are herbs or climbing 
shrubs, with wood of most remarkable structure and quite distinct 
from that of all other exogens, consisting of radiating plates of wood 
not disposed in rings. They are mostly of tropical distribution, being 
particularly abundant in South America. The flowers of Aristolochia 
are very diverse in shape and coloring; many species of this genus are 
ornamental in cultivation, as for 
example the familiar ‘‘Dutch- 
man’s pipe.”’ (A. macrophylla) 
und the tropical species sold as 
‘‘gooseflower’’? (A. fetens) a 
flower and leaf of which, one- 
half the natural size, are shown 
in Figure 74. The genus Asa- 
rum is well represented in the 
Eastern United States, A. Can- 
adense being the wild ginger or 
asarabacca. The species of 
Asarum are all stemless herbs 
; _ with handsome, often mottled, 
Fic. 75.—Parasitic flower of Raffesia Arnoldi, Fy 
very much reduced. Original. coriaceous leaves, and odd-look- 
ing flowers borne at the surface 
of the ground. 
These plants have very well-known medicinal properties; the roots 
are highly aromatic, and furnish a stimulant and a specific against 
snake poison; some species yield purgatives and vermifuges as well. 
The chief point of interest attaching to the group lies in the unac- 
countably close affinity to the Monocotyledons, as shown by the six 
stamens and six-celled capsule, and by the peculiar structure of the 
wood to which reference has been made above, 
Family Rafflesiaceae. Rafllesia Family. This truly remarkable 
family has a world-wide reputation as the best illustration of 
vegetable parasitism carried to the farthest possible extent. There are 
7 genera and about 20 species, all of which are reduced to mere flowers 
