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. rnacrophylJa) 

 and the tropical species sold as 

 "gooseflower" (J., fcettns) 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 

 Asartim are all stemless herbs 

 with handsome, often mottled, 

 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. Rafilesia 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 



Fig. 75.— Parasitic flower of Bafflesia Arnoldi, 

 very much reduced. Original. 



