210 
PACIFIC SCIENCE, Vol. XIII, April, 1959 
particularly in regard to the single secre- 
tory canal on the xylem face of veins. 
Duhatitia waialealae and D. latifolia show pe- 
culiarities of anatomy not closely matched by 
other species, and are probably rather iso- 
lated from whatever species each of them 
may most closely resemble. Each of these two 
species should probably form a "group” by 
itself. Inclusion of species other than those 
mentioned does not seem to be justified on 
the basis of present anatomical information. 
The material for Ar^roxtphium supports 
the interspecific relationships in that genus 
suggested earlier by the writer (1957<^). 
The suggestion of Keck (1936: 10) that 
Duhatitia, Arg^roxiphium, and Wilkesia must 
be considered a group within themselves 
could be defended on the basis of vegetative 
anatomy. The presence and distribution of 
trichome types, the patterns and nature of 
secretory canals, the lacunate character of the 
cortex, and the presence of carbonized resins 
in intercellular spaces are notable in this re- 
gard. In fact, the three genera could not be 
separated on the basis of some anatomical 
characters. Other structural features offer ex- 
cellent criteria, however, and Dubautia, Ar- 
g^roxiphhm, and Wilkesia are amply distinct 
in respect to leaf and node anatomy. 
Because there is little published information 
on anatomy of genera which are putatively 
related to these three genera, no comment can 
be made in this regard at present. The writer 
hopes to demonstrate, however, that charac- 
ters described here are worthy of considera- 
tion in comparing these genera with such taxa 
as the American genera of Madinae, Railli- 
ardella, and certain Senecioneae. 
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