Anatomy of Hesperomannia — Carlquist 
1. Hesperomannia Lydgatei Forbes 
Hesperomannia Lydgatei Forbes, Bernice P. 
Bishop Mus., Occas. Paper 4: 220, 1909. 
This species is the most distinct in the 
genus, by virtue of its geographic isolation 
(endemic to Kauai) and numerous morpho- 
logical and anatomical features. As shown 
above, the peduncles are glabrous and mark- 
edly narrower than those of the other spe- 
cies. The long, lanceolate involucral bracts 
are distinctive both in size and shape and in 
their anatomy. The lack of diffuse sclereids 
in corolla lobes has been mentioned earlier. 
In features of vegetative anatomy, however, 
no differences can be found between H. Lyd- 
gatei and the other species. The leaves and 
stems were found to be identical in shape 
and anatomy to some plants referred here to 
H. arborescens subsp. Swezeyi ( Judd 1244 , for 
example). Consequently, the difference in 
these respects suggested by Forbes (1909: 
220) cannot be maintained. Although it has 
not been collected since 1910, this species 
may still be extant. 
Representative specimens— Kauai, Wahi- 
awa Mts.: Lydgate , May 1908 (type, BISH 2 ), 
Forbes 190K (A, BISH, UC). 
2. Hesperomannia arbuscula Hillebrand 
Hesperomannia arbuscula Hillebr., FI. Hawaii. 
Is., 232, 1888. 
Compared with H. Lydgatei , the remaining 
taxa are remarkably uniform. Hesperomannia 
arbuscula has been maintained as distinct here 
because of its geographical distribution and 
the constancy of the leaf shape and indument 
characters. In addition, the occurrence of 
slightly different plants on Oahu and West 
Maui respectively suggests that if the two 
populations are to be recognized as separate 
subspecifically, they are best grouped as a 
species separate from H. arborescens. 
2 Abbreviations of herbaria according toj. Lanjouw 
and F. A. Stafleu, Index Herbariorum, Part I, 1954, 
Utrecht. 
213 
2A. Hesperomannia arbuscula subsp. 
arbuscula 
This taxon is known only from the type 
collection. Since repeated exploration of West 
Maui has failed to rediscover this plant, it may 
be extinct. Because the type at Berlin is ap- 
parently destroyed and the sterile type frag- 
ment at the Bishop Museum is inadequate, 
the isotype material in the Gray Herbarium 
remains the only usable material. 
Representative specimens — West Maui: 
Bishop , 1871 (type fragment, BISH; isotype, 
GH). 
2B. Hesperomannia arbuscula subsp. 
oahuensis (Hillebr.) comb. nov. 
Hesperomannia arborescens var. oahuensis Hil- 
lebr., FI. Hawaii. Is., 232, 1888. 
Hesperomannia oahuensis (Hillebr.) Degener, 
Flora Hawaiiensis. 1938. 
Hesperomannia oahuensis , like the earlier va- 
riety of Hillebrand, was erected on the basis 
of material from Mt. Kaala, Oahu. Since 
Degener copied the description of H. arbus- 
cula from that of Hillebrand, did not illustrate 
H. arbuscula , and cited the type only as "be- 
fore 1888," it seems likely that Degener did 
not study the fertile specimens of H. arbuscula 
(mentioned above) extant at that time. Ex- 
amination of both Oahu and Maui material 
reveals the small differences noted in the key 
above, but close identity in all other char- 
acters. Contrary to Degener ’s description of 
H. oahuensis , leaves with dentate margins may 
be found in this taxon. 
Representative specimens— Oahu, Mt. Ka- 
ala and vicinity: Hillebrand , 1871 (GH), Deg- 
ener and Salucop 11200 (BISH, GH). 
3. Hesperomannia arborescens Gray 
Hesperomannia arborescens Gray, Amer. Acad. 
Arts and Sci., Proc. 6: 554, 1886. 
The type specimen of H. arborescens was 
collected on Lanai. Subsequent to Gray’s de- 
scription of this species, the first in the genus, 
