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A TEXTBOOK OF THEORETICAL BOTANY 



Fig. 1540. — Sediiin {Rhodiola) rosea. 

 Flowering shoot. 



The flowers are apetalous 

 but the calyx consists of six 

 coloured lobes which are 

 united at the base. There are 

 twelve stamens which are peri- 

 gynous and inserted at the top 

 of the calyx tube. There are six 

 carpels which form a polycar- 

 pellary gynoecium, each with 

 one, or rarely two, basal, erect 

 ovules. The fruit is an etaerio 

 of follicles, which is sur- 

 rounded by the accrescent 

 calyx, covered outside by 

 dense hairs. 



The fourth family, the 

 Podostetnaceae, includes a 

 number of very remarkable 

 though very reduced aquatic 

 plants. Some twenty-two gen- 

 era are recognized and include 

 about 100 species. They are all 

 of them tropical but the family 

 is widely distributed. The ana- 

 tomical modifications in these 



Cephalotiis folliciilaris which is found only 

 in marshes in Western Australia (Fig. 

 1 541). It is a remarkable insectivorous 

 plant, whose leaves are developed into 

 pitchers. These pitchers resemble in 

 structure those of Nepenthes but are only 

 produced by some of the leaves. The 

 lower leaves of the rosette form pitchers 

 while the upper leaves are flat, elliptical 

 and entire. Only the latter assimilate 

 carbon dioxide. 



Fig. 1 541. — CepJialntiis foUicularis. Habit of the 

 flowering plant. {After Robt. Brozin.) 



