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PACIFIC SCIENCE, Vol. XI, April, 1957 
various authors have found difficulty in sep- 
arating specimens collected later on Oahu 
from the Lanai material. Rock (1913: 507) 
and Skottsberg (1944: 512) find considerable 
similarity. Examination of the type specimens 
of all the taxa treated here as H. arborescens, as 
well as the numerous specimens which have 
been collected at various stations in the Koo- 
lau Mts., Oahu, reveals that considerable 
variability exists in this species. The descrip- 
tions of Degener for taxa in this group do not 
allow for this variability, as the comments 
below will indicate. The characters used by 
Degener in separating the species of this 
group have been found to have frequent ex- 
ceptions and various degrees of intermediacy. 
For this reason the writer has found it in- 
advisable to maintain the species proposed 
by Degener. 
3A. Hesperomannia arborescens subsp. 
arborescens 
The Lanai population of H. arborescens has 
not been encountered since a single tree was 
seen in 1931, and may now be assumed to be 
extinct. It is only dubiously separable from 
Oahu material. As the type specimen and the 
collection Munro 492 show, clusters of fewer 
heads, pubescent involucral bracts, and glan- 
dular trichomes on the achenes, thought by 
Degener to be characteristic only of Oahu 
plants, may be found in the Lanai material. 
The latter is maintained as a subspecies here 
because of its geographical isolation and 
seemingly slightly longer achenes, although 
it is possible that longer achenes may be 
found in future collections of mature Oahu 
material. The leaves do not match those of a 
particular Oahu population in that they com- 
bine a broad shape with a prominently toothed 
margin and are glabrous. These leaf charac- 
ters, however, may all be found in Oahu 
plants. 
Representative specimens— Lanai, near sum- 
mit: Mann and Brigham 357 (type and iso- 
type, GH), Hillebrand , 1874 (GH), Munro 492 
(A, BISH). 
3B. Hesperomannia arborescens subsp. 
Bushiana (Degener) comb. nov. 
Hesperomannia Bushiana Degener, Flora Ha- 
waiiensis. 1933. 
The small population found at the crest of 
Halawa ridge, Koolau Range, Oahu, is the 
most distinctive in the H. arborescens complex. 
The type specimen and the collection Degener 
11927a show that the heads are uniformly 
solitary and smaller than in subsp. Swezeyi. 
The smaller head size, however, is not so 
pronounced as Degener’s description indi- 
cates. Heads with as few as 30 flowers may 
be found in specimens of subsp. Swezeyi such 
as Degener 10007; H. Bushiana was described 
by Degener as having "approximately 25 
flowers" per head. Solitary heads are occa- 
sional or frequent in populations treated here 
as subsp. Swezeyi. The combination of narrow 
leaves with toothed margins is not represented 
in other populations, but equally narrow 
leaves and leaves with toothed margins may 
be found independently in various localities, 
so the combination of these two characters 
in subsp. Bushiana is not surprising. In view 
of the closeness of this plant to some popula- 
tions of subsp. Swezeyi , it has seemed prefer- 
able to recognize it as a subspecies in this 
complex, rather than a species coordinate 
with H. arborescens. 
Representative specimens — Oahu, Koolau 
Range, Halawa: Bush et al. 9981 (type, BISH), 
Degener 11927a (BISH). 
3C. Hesperomannia arborescens subsp. 
Swezeyi (Degener) comb. nov. 
Hesperomannia Swezeyi Degener, Flora Ha- 
waiiensis. 1933. 
Hesperomannia Bushiana var. Fosbergii Degener, 
Flora Hawaiiensis. 1937. 
Within this subspecies are included all the 
populations of the Koolau Range except H. 
arborescens subsp. Bushiana. This group has 
been previously divided by Degener into H. 
Swezeyi and H. Bushiana var. Fosbergii. He 
