MANUAL OF NATURAL HISTORY. 391 



wood and true bark ; wood arranged in concentric 

 circles, augmented by growth from without, the 

 hardest parts being internal ; bark separable ; 

 epidermis furnished with stomata; leaves reticulated, 

 usually articulated to stem ; type of fructification 

 quinary or quatenary ; embryo dicotyledonous; ger- 

 mination exorhizal. 



I. SUB-CLASS. — Bisexual-Exogens (Monoclinese). 



Male and female organs of reproduction on the 

 same flower. 



I. ALLIANCE. — Epigynous-Exogens (Epigynese). 



Flowers commonly hermaphrodite ; stamens grow- 

 ing to the side of either the calyx or corolla ; ovary 

 inferior or nearly so. 



I. ORDER. — Asarals (Asarales). 



Flowers monochlamydeous ; embryo small, lying 

 in a large quantity of albumen. 



1. Family. — Birthvjorts (Aristolochiacese). Herbs 



or shrubs, often climbing ; wood without 

 concentric zones ; leaves alternate, simple, 

 stalked ; flowers solitary, axillary, of a dull 

 colour; stamens 6-12; ovary 8-6~celled ; 

 ovules 00 ; fruit dry or succulent. Abound 

 in warm parts of South America, rare in 

 North America, Europe, Siberia and India; 

 yield Asarabacca and Virginian Snake-root. 



2. Family. — Mistletoes (Loranthaceae). Shrubs, 



