126 FAMILIES OF FLOWERING PLANTS 
carpels, and the perigynous flower, in which they 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. 111. Flowers of Rose and Apple Families; (1), hypogynous flower of Potentzlla, the sepals, 
petals and stamens borne on the receptacle beneath the carpels; (2), perigynous flower of Alchemilla, 
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 
Porteranthus, known as “Indian physic” possess medicinal properties; 
they are herbs, with graceful foliage and delicate white flowers. Quil- 
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 
