Vor. I] STEWART—BOTANY OF THE GALAPAGOS ISLANDS 27. 
The Rhizophoraceae and Combretaceae include some of the 
most important elements of the littoral vegetation. Rhizophora 
Mangle of the first of these families forms dense low forests 
below high tide mark, while Conocarpus erectus and Laguncu- 
laria racemosa of the second occur farther back as bushes and 
small trees. 
The various species of Jpomoea are the most significant 
members of the Convolvulaceae in that some of the most im- 
portant of the herbaceous lianes of the islands are members 
of the genus. This genus also furnishes species which occur 
under all conditions, halophytic, xerophytic, and mesophytic. 
The Boraginaceae furnish some noteworthy elements of the 
flora in all of the regions. The various species of Cordia con- 
stitute important factors of the flora in the dry and transition 
regions, while the species of Yournefortia provide some of the 
most common bushes in all of the regions, especially in the 
moist and grassy. 
Avicennia, Clerodendron, and Lantana are the three genera 
of the Verbenaceae which are of prime importance. Avicennia 
officinalis forms an important element of the littoral vegetation 
in the form of low forest trees, while the two remaining genera 
furnish some of the most characteristic bushes of the dry and 
transition regions. 
The Solanaceae are the eighth largest family in number of 
species on the islands, but are of rather secondary importance, 
as the species for the most part are herbaceous and not espe- 
cially abundant in any of the regions except during the spring 
season. At that time they furnish several of the common 
weeds. 
The Rubiaceae stand next in importance to the Solanaceae 
in number of species, but most of these are relatively small in 
size. This is one of the most important families represented in 
the archipelago in that it contains common species in all of the 
regions. The various species of Borreria are very frequent in 
the dry regions, some of them inhabiting the most desert situa- 
tions, even to the exclusion of almost all other species of plants. 
Bushes of Chiococca alba often form an important element of 
the flora in the transition regions, and Psychotria rufipes is of 
prime importance in the Scalesia forests in the moist regions, 
where it is one of the most abundant bushes. 
