474 



PKIMULACE,E. 



are so called on account of the utricles or bladders connected vvitli 

 the leaves (^ 164). In the interior of these vesicles a mucous fluid 

 is found along with cellular projections in the form of hairs. Utri- 

 cularia nelumbifolia grows in the water which collects in the bottom of 

 the leaves of a large Tillandsia in Brazil. It sends out runners and 

 shoots, and often in this way unites several plants of Tillandsia. The 

 leaves are peltate, and more than three inches across, while the flower- 

 ing stem is two feet long. 



974. Order 141. Primnlaceie, the Primrose Family. (Monopet. 

 Hypog.) Calyx 5- rarely 4-cleft (fig. 272), inferior or half superior, 

 regular, persistent (figs. 675 c, 677). Corolla monopetalous (fig. 295 p), 

 hypogynous (fig. 675), rarely perigynous, with the limb 5- rarely 

 4-cleft, sometimes (fig. 543). Stamens inserted on the corolla, 

 equal in number and opposite to its segments (figs. 674, 675). Ovary 

 free, (figs. 675, 676 o), rarely adherent to the base of the calyx, 1-celled; 

 ovules 00, usually amphitropal; style 1 (fig. 675 s); stigma capitate 

 (fig. 675). Fruit a capsule, opening with valves (fig. 677), or with a 

 h'd (fig. 458). Seeds numerous, peltate (fig. 678), attached to a free 

 central placenta (fig. 677); embryo straight (fig. 680), enclosed within 

 fleshy albumen, and lying across the hilum (fig. 679). Herbaceous 



plants, with leaves usually opposite, and frequently radical, exstipulate; 

 flowers on simple or umbellate scapes. They are natives chiefly of 



Figs. 674-680. Organs of fructification of Primula elatior, illustrating the natural order Priro- 

 ulacese. 



Fig. 674 Diagram of the flower, with five imhricate divisions of the calyx, five segments of 

 the corolla, five stamens opposite the corolline segments, and five carpellary leaves, surrounding 

 a free central placenta. 



Fig. 675. Vertical section of the flower, c, Inferior calyx, p, Monopetalous corolla, e, Sta- 

 mens attached to the corolla, o, Superior ovary, s. Style with capitate stigma. 



Fig. 676. Ovary cut vertically, to show the free central placenta covered with ovules. *, Base 

 of the style. 



Fig. 677. Vertical section of the fruit /, Pericarp, p, Placenta with numerous seeds, some 

 of which have been detached. 



Fig. 678. Peltate amphitropal seed separated, h, Hilum. 



Fig. 679. Seed cut vertically. <, Integuments (spermoderm). A, Hilum. p, Fleshy perisperm 

 (albumen), e. Transverse embryo lying across the hilum. 



Fig. 680. Embryo with cotyledons and radicle. 



