1917] MACCAUGHEY—HAWAIIAN FLORA 387 
background of this lava flow vegetation, it is necessary to sketch 
briefly the salient features of the Hawaiian volcanic mountains. 
Detailed accounts may be found in such standard works as those 
of Hircucock, BricHam, DANA, and Dutton. 
It will be noted that the present paper deals largely with the 
ecological conditions under which the lava flow vegetation exists. 
A comprehensive annotated list of the lava flow plants is now 
appearing in the Journal of The Linnaean Society. 
Classification of islands 
From the standpoint of area occupied by lava flows, cinder 
fields, and other waste lands resultant from volcanic activity, the 
islands may be divided into two groups: (1) the lesser islands 
(Niihau, Kauai, Oahu, Molokai, Lanai, Kahoolawe); and (2) the 
greater islands (Maui and Hawaii, see figs. 1, 2). The lesser 
islands are, as a whole, of much greater antiquity than Maui and 
Hawaii. The erosive agencies have been at work for a much 
longer time, hence the lava flows have been almost wholly turned 
into soil. There are some traceable flows still existent on some 
of the lesser islands, Kauai, Oahu (figs. 3, 4, 5), Molokai, and 
Lanai, for example, but these are relatively non-consequential as 
compared with the great stretches of lava covered country on 
Hawaii and Maui. The lava waste lands, above the timber line, on 
Mauna Loa alone, for example, occupy a greater area than the 
entire island of Oahu, Kauai, or Molokai. Thus a discussion of 
the vegetation of the Hawaiian lava flows is naturally restricted 
chiefly to a consideration of the islands of Maui and Hawaii, the 
largest and youngest end of the long archipelago. No account 
is given in this paper of the tiny islands which are strewn over a 
long axis for 1800 miles to the westward of the larger, inhabited 
islands. Some of these are volcanic rocks, but the majority are 
tiny reefs and shoals.t Their total area is only 6 sq. miles. All are 
highly xerophytic. 
IsLAND OF HAwat.—Hawaii, the largest island of the archi- 
pelago (4015 sq. miles), is about the size of the state of Connecticut, 
with a maximum diameter of 93 miles (fig. 2). Its area is greater 
* MacCaucuey, V., The little end of Hawaii. Jour. Geography 15:23-26. 1916. 
