314 YIEWS, &C. PHYSIOGNOMY OF PLANTS. 



leafless, thin, thread-like, articulated branches, and their 

 joints furnished with membranous, toothed spathes, have been 

 compared by travellers,* according to differences of species, 

 either with arborescent Equisetacese (Horsetails) or with our 

 Scotch firs. I have been much struck with the singular ap- 

 pearance of leaflessness presented by the small thickets of 

 Colletia and Ephedra in South America, near the coast of Peru. 

 Casuarina quadrivalvis penetrates, according to Labillardiere, 

 as far south as 43 in Tasmania. The mournful form of the 

 Casuarina is not unknown in the East Indies and even on the 

 eastern coast of Africa. 



(23) p. 227" Acicular-leaved trees" 



The family of the Coniferse (including the genera of Dam- 

 mara, Ephedra, and Gnetum of Java and New Guinea, which 

 are essentially allied to it, though distinctly separated by the 

 form of the leaf and the whole conformation), plays so import- 

 ant a part in consequence of the number of individuals in 

 each species, and by its geographical diffusion, while it covers 

 in the northern temperate zone, as a social plant, such exten- 

 sive districts, that we are almost compelled to wonder at the 

 inconsiderable number of the species. We are not acquainted 

 with so many Coniferce by three-fourths as there are Palms 

 already described, nay, the Coniferse are numerically less 

 than the Aroideae. Zuccarini, in his " Contributions to 

 the Morphology of the Coniferae,"! enumerates 216 species, 

 of which 165 belong to the Northern and 51 to the 

 Southern hemisphere. These proportional numbers must 

 now, in consequence of my researches, be differently ex- 

 pressed, since, with the species of Pinus, Cupressus, Ephedra, 

 and Podocarpus, which Bonpland and I discovered in the 

 tropical part of Peru, Quito, New Granada, and Mexico, the 

 number of the cone-bearing trees flourishing between the 

 tropics amounts to 42. The excellent and latest work of 

 Endlicher^: contains 312 species of Conifers now living, and 

 178 of a primeval mundane period which are now buried in 

 the coal formation, in variegated sandstone, in keuper, and in 



* See Darwin, Journal of Researches, p. 449. 



+ See his Abhandl der Wiss. zu Miinclien, bd. iii. 1837-1843, 

 s. 752. 

 J Synopsis Coniferarum, 1847. 



