SECT, n rHANEROGAAIIA 611 



two ; ovary uni- or bi-locular. Fruit a capsule or a berry containing 

 an indefinite number of albuminous seeds. 



Important Genera. — Saxifraga, Saxifrage, small herbaceous plants which are 

 especially numerous on crags and rocky ground in mountainous districts. They 

 have a rosette of radical leaves (cf. p. 15, chalk glands) and bear numerous 

 pentamerous flowers grouped in various types of inflorescence. The two partially 

 inferior carpels are distinct from one another above. Farnassia paluslris is common 

 on wet moors, pentamerous flower with 4 carpels. Ovary unilocular, placentation 

 parietal. One whorl of stamens modified into palmately divided staminodes, which 

 serve as nectaries. The species of Jiibcs have an inferior ovary which develops into 

 a berry, and on this account are commonly cultivated. IL ruhrum (Fig. 623), Red 

 Currant, It. niijrum, Black Currant, R. grossularia, Gooseberry. Other Saxifragaceae 

 are favourite ornamental plants, e.g. Kihes aureum and R. sanguineuvi, Hydrangea, 

 Philadelplius, and Deutzia. 



Order 19. Rosiflorae 



Family Rosaeeae (^"'). — This is the only family in the order. Herbs, 

 shrubs, and trees with alternate, stipulate leaves, showing considerable 

 differences in form and habit. Distributed throughout the Avorld. 

 Flowers nearly always actinomorphic, with the members in whorls. 

 K 5, C 5. Stamens usually numerous. Flowers perigynous or epi- 

 gynous ; one to many free carpels borne on the expanded, convex, or 

 hollowed floral axis. In the epigynous flowers only the styles are 

 free. The floral axis in many cases takes jiart in the construction of 

 the fruit. Seeds usually without endosperm. 



The apocarpous pistil and numerous stamens are characteristic of .the Rosaeeae 

 (Fig. 624). Both these features are also found in the Ranunculaceae or generally 

 in the Polycarpicae, but the floral members are there spirally arranged while 

 in the Rosaeeae they are in whorls. The latter are further distinguished by the 

 peculiar development of the floral axis (Fig. 625). In many cases the increase in 

 number of members of the androecium and gynaeceum proceeds from an intercalary 

 zone of the hollowed floral axis, and continues for a considerable period. The 

 introduction of new members is determined by the spatial relations, so that diff"er- 

 ences in the numbers of members are found in individuals of the same species. 



The family is divided into a number of sub-families. 



(a) Spiraeac. Typically pentamerous flowers, other numbers of members in the 

 whorl are less frequent. Carpels free or united, each containing two or more 

 ovules. Fruits usually dehiscent. Floral axis expanded as a more or less flat disc. 

 The genus Spiraea has inflorescences bearing numerous flowers ; many species are 

 cultivated as ornamental shrubs (Fig. 624 E). Quillaja Sa]Jonaria (Fig. 626), from 

 Chili, is an evergreen tree with shortly stalked, alternate, leathery leaves and 

 terminal dichasia usually consisting of three flowers. The flower has a five-toothed, 

 nectar- secreting disc projecting above the large sepals. Five of the stamens stand 

 at the projecting angles of the disc opposite the sepals ; the other five are inserted 

 opposite the petals at the inner margin of the disc. Petals narrow, white. Ovary 

 superior. Only the middle flower of the dichasium is hermaphrodite and fertile, 

 the lateral flowers are male and have a reduced gynaeceum. Fruit star-shaped, 



