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



The Compositae stand second in number of species of all of 

 the families of vascular plants occurring on the islands. Many 

 of the common herbaceous annuals of the dry and transition 

 regions, as well as some of the most important bushes, belong 

 to this family. The Compositae are however most strikingly 

 represented in the moist regions, where extensive forests of 

 Scalesia, made up for the most part of 5. pedunculata, occur. 

 This genus is also well represented in both the dry and transi- 

 tion regions by shrubby species, which sometimes occur in 

 large numbers over considerable areas. Other noteworthy 

 members of the family are the species of Erigeron and Lipo- 

 chaeta, both of which are important where they occur. 



The remaining families of vascular plants represented on the 

 islands contain but few species and for the most part are of 

 relatively little importance. 



The plants which occur under halophytic or semihalophytic 

 conditions are included in the following genera : Ammophila, 

 Atriplex, Avicennia, Batis, Cacahus, Conocarpus, Coldenia, 

 Cryptocarpus, Eleocharis, Heliotropium, Hibiscus, Hippomane, 

 Ipomoea, Laguncularia, Lycium, Maytenus, Najas, Rhizo- 

 phora, Ruppia, Salicornia, Scaevola, Sesuvium, and Sporo- 

 bolus. 



Hydrophytes are comprised in Asolla, Callitriche, Eleo- 

 charis, Lemna, Myriophyllum, Jussiaea, and Salvinia, all of 

 which are of little importance in the composition of the flora, 

 as they mostly occur periodically when there is a supply of 

 fresh water in the pond's and brooks. 



Outside of a few species of ferns, the only vascular epiphytes 

 are three species of orchids, two or three species of Peperomia, 

 and a Tillandsia, the last of which is the most common and 

 largest of the epiphytic plants. All of the above are practically 

 confined to the transition and moist regions, occurring above 

 the last in only a few instances. Phanerogamic parasites are 

 represented by four species of Phorodendron, only one of which 

 is sufficiently abundant to be of importance in this respect, and 

 two species of Cuscuta. The first of these parasites is found in 

 all of the regions, but is most abundant in the moist, while the 

 second is confined to the dry and transition zones and so far 

 as was observed only appears for a short time during the spring 

 months. 



