526 



BOTANY 



or red, are clustered in loose, dichasial inflorescences. Many species are familiar 

 as ornamental plants. 



To the Passiflorinae belong also the Zoasaceae, a tropical American family 

 consisting for the most part of herbaceous climbers, often having stinging hairs. 

 A few species are cultivated. 



Order 9. Opuntinae 



With the single family Caetaeeae. — Flowers epigynous, actino- 

 morphic, hermaphrodite ; perianth and androecium ACYCLIC; gyncecium 

 consisting of a large, indefinite number of carpels ; ovary uni- 

 locular, with many parietal placentae ; ovules with long 

 funiculi ; fruit a berry. Herbaceous and woody plants, with fleshy 

 axes and usually reduced, thorn-like leaves (Figs. 490, 491). 



Flo. 490.— Epiphyllvm truncatum. 2, Flower cut through 

 longitudinally. (Nat. size, after Wossidlo.) 



Fig. 491. — Ojmntia monaeantha, show- 

 ing flower and fruit. (After Schu- 

 mann, £ nat. size.) 



In many Caetaeeae (Mamillaria) the assimilatory vegetative system 

 is reduced to an angular, cylindrical, or spherical axis, entirely 

 destitute of foliage-leaves ; in other Caetaeeae, again, the assimilatory 

 organs are represented by a system of branching axes which may be 

 prismatic (Cereus) or flattened, either band-shaped (Epiphyllum, Fig. 

 490) or ovate (Opuntia, Fig. 491). The clusters of spines occurring on 

 the axes represent in most cases reduced leaves. Peireskia is the only 

 genus possessing well-developed foliage-leaves. 



Peculiar as the general appearance of the Caetaeeae is, it is not 



