126 



FAMILIES OF FLOWEKING PLANTS 



carpels, and the perigynous flower, in wliicli tliey are borne on the rim 

 of the receptacle around the carpels. 



Owing to the vast extent of the family, and the large number of 

 noteworthy plants it contains, we shall find it advantageous to discuss 

 the various subfamilies or general groups in some detail. 



The Spiraeoideae are typified by the genus Spiraea, represented 

 by numerous wild species throughout the United States, and by several 

 ornamental exotics in cultivation. The spiraeas are mostly under- 

 shrubs, with large, dense clusters of small red, pink or white flowers. 

 The petals are borne on the calyx in this group, and the carpels are 



From Coulter's Plant Structures. Copyright, 1900, by D. Appleton & Co. 

 Fig. III. Flowers of Rose and Apple Families; (i), hypogynous flower of Po/entt'l/a, the sepals, 

 petals and stamens borne on the receptacle beneath the carpels; (2), perigynous flowerof Akhemilla, 

 these organs borne on the rim of the receptacle above the carpel; (3), epigynous flower of the apple, 

 the parts arising from the summit of the ovary. After Focke. 



comparatively few in number, not exceeding 5. The two species of 

 Porterantlms, known as "Indian physic" possess medicinal properties; 

 they are herbs, with graceful foliage and delicate white flowers. Qidl- 

 laja Saponaria, a Chilean tree, has bark which yields saponin in abund- 

 ance from which a very good quality of soap is manufactured. 



In the subfamily Rosoideae, we note a handsome Asiatic shrub 

 {Kerria Japonica), whose golden-yellow double flowers have been con- 

 spicuous in the Washington parks during the past few weeks. Potentilla 

 may be ranked as the largest of the few rosaceous weed genera in this 

 country; it includes about 150 species, natives of the north temperate 

 zone, and with very few exceptions herbaceous in habit. They have 



