216 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



tation. The forms of this species which occur in the dry region 

 are usually rather low and covered with small leaves of a 

 decidedly gray color, due to the heavy covering of trichomes. 

 Those forms which occur higher up in the transition and 

 moist region are larger, sometimes attaining the size of small 

 trees. On these the leaves are larger and with a much lighter 

 covering of plant hairs. Species of Euphorbia occur to some 

 extent in all of the regions, but are most abundant in the dry 

 and lower transition, the species which occur here being for 

 the most part bushy in character with small and inconspicuous 

 leaves. The species which occur above the transition region 

 are mostly procumbent herbaceous forms. Of the remaining 

 genera Acalypha and Hippomane are the most important. 

 Acalypha is represented by fourteen species and varieties, all 

 of which are endemic. They are found for the most part in 

 the transition and moist regions. Hippomane Mancinella 

 occurs in various habitats, halophytic, xerophytic, and meso- 

 phytic, with apparently no decided change in form in any of 

 them. 



The Celastraceae have but a single representative, Maytenus 

 ohovata, bushes of which form a very important element of the 

 flora of the dry regions, especially in the neighborhood of the 

 coast. It occurs more or less abundantly throughout the dry 

 and transition regions, in the first of which it is about the only 

 green bush of any size during a great part of the year. 



The Sapindaceae are one of the smaller families in number 

 of species, but are important from the fact that Cardiospermum 

 furnishes a rather important herbaceous liane and Sapindus 

 Saponari the largest forest tree found on the islands. The 

 Rhamnaceae are represented by Discaria pauciHora, bushes of 

 which occur abundantly in the lower parts of the dry regions. 



Outside of a few herbaceous forms, Gossypium barbadense is 

 the most important member of the Malvaceae. Bushes of this 

 species occur in greater or less abundance in the dry and transi- 

 tion regions. 



The Cactaceae are represented by several species of Cereus 

 and Opuntia, most of which form rather striking elements of 

 the flora. Both genera have both bushy and arborescent 

 species, and are found for the most part in the dry and transi- 

 tion regions. 



