414 



BOTANY 



Engler includes under the Apetalae the following orders : 



1. Verticillatae 



2. Piperales 



3. Salicales 



4. Myricales 



5. Balanopsidales ? 



6. Leitneriales ? 



7. Juglandales 



8. Fagales 



9. Urticales 



10. Proteales 



11. Santalales 



12. Aristolochiales 



13. Polygonales 



Order I. Verticillatae 



This order includes but a single genus, 

 Casuarina (Fig. 392), trees of very pecul- 

 iar habit, with Equisetuin-like, leafless 

 branches, and simple flowers consisting 

 of a single stamen, or of two carpels, one 

 of which is usually sterile. The genus is 

 especially developed in Australia, but occurs also in tropical Asia and the Pacific 

 islands. C. equisetifolia is not infrequently planted in California. 



In the structure of the flowers and development of the embryo-sac, Casiiarina 

 shows certain resemblances to the Gnetales, and may be related to them. Fer- 

 tilization is chalazogamous. 



FIG. 392. Casuarina equisetifolia. 

 A, branch showing the reduced scale- 

 leaves, I. B, branch with ripe cone 

 of fruit ? . 



FIG. 393. A, B, Saururus cermtus. A, branch with inflorescence, somewhat re- 

 duced. B, single flower enlarged. C, Peperomia trinervis Cross-section of 

 stem (X 14). 



