390 THE AKISTOLOCHIA FAMILY. [Asarum. 



Perianth combined with the ovary at the base, either 3-lobed 

 or very irregular. Stamens usually 6 or 12, inserted on the 

 summit of the ovary within the perianth. Ovary and fruit in- 

 ferior, 3- or 6-celled, with several seeds in each cell. Albumen 

 fleshy, with a minute embryo. 



A small family, widely spread over the globe, chiefly in the tropics. 

 The principal genus, Aristolochia, remarkable for the tubular perianth, 

 often curved, terminating in an oblique, entire limb, is not British ; but 

 the tall, climbing A. Sipho, and some other species, are cultivated in our 

 gardens ; and A. Clematitis (Eng. Bot. t. 398), from southern Europe, 

 has been found in some parts of England, as an escape from gardens. 

 It is an erect perennial, of about 1 J feet, with broadly cordate leaves, 

 and slender, yellowish-green flowers clustered in their axils. 



I. ASARUM. ASARUM. 



Perianth campanulate, regular, 3 -cleft. Stamens 12. 



A genus of very few species, dispersed over Europe, temperate Asia, 

 and North America. 



1. A. europseum, Linn. (fig. 884). Asarabacca. — A low perennial, 

 with a shortly creeping rootstock, and very short, inconspicuous stems. 

 Leaves usually 2 only, almost radical, on long stalks, orbicular-cordate 

 or kidney-shaped, 1 to 2 or even 3 inches broad. Between them is a 

 single greenish-brown flower, about half an inch long, on a short, re- 

 curved stalk ; the perianth divided to the middle into 3 broad, pointed 

 lobes. 



- In woods and shady places, in central and southern Europe and tem- 

 perate Russian Asia, extending northwards into southern Scandinavia. 

 Rare in Britain, but believed to be a true native in a few localities in 

 the north of England and in Wiltshire. Ft. May. 



LXVIII. EUPHORBIACE^. THE SPURGE FAMILY. 



Herbs, shrubs, or trees, much varied in foliage and inflores- 

 cence. Flowers always unisexual, with or without a perianth. 

 Stamens various. Ovary consisting of 3 (rarely 2 or more 

 than 3) united carpels, each with 1 or 2 pendulous ovules. 

 Styles as many as carpels, entire or divided. In the fruit these 

 carpels separate from each other and from a persistent axis, and 

 usually open with elasticity in 2 valves. Seed with a large 

 embryo usually enclosed in fleshy albumen. 



A vast family, chiefly tropical, so varied in aspect that no general 

 idea can be formed of it from the three genera which represent it in 

 Britain, nor is the connection between these three genera easily under- 

 stood without a comparison with intermediate exotic forms. The 

 structure of the ovary and fruit is peculiar to this family among 

 unisexual plants. 



