414 BOTANICAL GAZETTE [NOVEMBER 
sandwicensis); (2) species with moderate range (Charpentiera 
obovata, Daucus pusillus, Gossypium tomentosum); and (3) species 
with a very narrow range (Argyroxiphium virescens., Geranium spp., 
Straussia spp.). 
Xerophytic characters of lava flow plants 
PuBESCENCE.—Of the 182 species listed as occurring on the 
lava flows, 62, or 33 per cent, are characterized by coatings of hairy 
or woolly tomentum. The pubescence may cover the under 
surfaces of the leaves, the entire leaves, the young shoots, the 
inflorescences, or all aerial parts of the plant. The most pro- 
nounced examples of tomentose envelopment occur in the follow- 
ing genera: Argyroxiphium, Gnaphalium, Chenopodium, Sida, 
Gossypium, Nototrichium, Waltheria, Abutilon, Geranium, Lobelia, 
and Plantago. The point must be emphasized that with many 
indigenous Hawaiian plants there is exceeding variability as to 
pubescence; plants of the same species from various localities will 
show every gradation from perfectly glabrous to very hairy. 
This variation does not give evidence of intimate association with 
ecological habitat, although in a general way the glabrous forms 
characterize the rain forest and the pubescent forms the more 
arid situations. There are many exceptions to this rule, however, 
and a very considerable proportion of the pubescence seems to 
be without obvious ecological significance. 
WAXY OR VISCID EXCRETIONS.—These are much less prevalent 
than the pubescent or coriaceous protections. Typical instances 
are Argemone mexicana, Dodonea eriocarpa, Gardenia Brighamt, 
Pisonia sandwicensis, P. inermis, Plumbago zeylanica, Raillardia 
spp., Sphacele hastata, Styphelia spp., Tetramolopium spp., Vac- 
cinium spp., Myoporum sp. 
THORNS AND PRICKLES.—A small number of the lava flow 
plants are thorny or prickly; the condition characterizes intro- 
duced weeds rather than the indigenous vegetation, as shown by the 
following: 
Prickly Thorny Total 
4 I 5 
iitremte so 4 5 9 
