300 OUTLINE OF PLANT GEOGRAPHY 



The Galapagos Islands 



The Galapagos Islands, 580 miles west of Ecuador and lying 

 directly on the equator, are of great interest both to the zoologist 

 and the botanist. 



The islands are entirely volcanic in formation and attain a 

 height of 2,000 to 2,500 feet. Both animals and plants give evi- 

 dence of a very long period of isolation. 



The most comprehensive account of the vegetation is given by 

 Professor B. L. Robinson with the co-operation of several other 

 specialists. 1 



The climate is very hot and dry, and at the lower elevations the 

 vegetation is decidedly xerophytic, made up of scattered small- 

 leaved shrubs, wiry grasses and undershrubs, and a few tree 

 Cacti. 



Inland are saline lakes, and about these and in brackish swamps, 

 as well as along the coast, are a good many saline plants or "hal- 

 ophytes." First in importance are the mangroves (Rhizophora 

 mangle, Avicennia officinalis), while other characteristic forms are 

 species of morning glories (Ipomoea, Calystegia), Verbena, 

 Heliotropium, Atriplex, and several others. 



Epiphytes are infrequent, but there is a Bromeliad (Tillandsia) 

 and an orchid (Epidendrum) and several species of Peperomia. 

 Showy flowers are scarce. 



As to the origin of the Galapagos flora, Robinson says: "While 

 it is clear that the Galapageian flora is only an outlying portion 

 of the American flora ... it is impossible to trace its relation- 

 ship closely to any one section of the Pacific American vege- 

 tation." 2 



Omitting the algae, fungi and bryophytes, which have a few 

 peculiar species, there are 499 species of vascular plants recorded. 

 Of these 52 are ferns and 445 spermatophytes (flowering plants). 

 Only three ferns are endemic, while 202 species, 15 varieties, and 

 19 forms constituting 44.4 per cent of the whole spermatophyte 

 flora are peculiar to the islands. 



"Flora of the Galapagos Islands" (Papers from the Hopkins-Stanford Expedi- 

 tion to the Galapagos Islands), Proceedings of the American Academy of Arts and 

 Sciences, Vol. XXXVIII, No. 4, October, 1902. 

 2 hoc cit., p. 239. 



