Systematic Anatomy of Hesperomannia 
Sherwin Carlquist 1 
The genus Hesperomannia (Compositae, tribe 
Mutisieae) has attracted interest because of its 
arborescent habit, its restriction to certain of 
the Hawaiian Islands, and its rarity in the 
locations in which it is found. The purpose 
of the present paper is to survey the anatom- 
ical diversity which exists in the genus and 
relate it to gross morphological characters in 
an attempt to achieve an acceptable classifica- 
tion. The affinities of Hesperomannia , as sug- 
gested particularly in terms of anatomical 
characters, are to be discussed in later studies. 
Within the genus, however, anatomical fea- 
tures seem illuminating in demonstrating the 
most natural taxonomic groupings. 
ACKNOWLEDGMENTS 
The writer wishes to express appreciation 
to the curators of the herbaria named below 
for loan of specimens. Dr. Harold St. John 
of the University of Hawaii kindly conducted 
a field trip on which the writer was able to 
collect material of Hesperomannia. Acknowl- 
edgment is offered to Dr. Reed C. Rollins 
and Dr. Grady Webster for reading the manu- 
script and suggesting improvements. 
MATERIALS AND METHODS 
Vegetative material of the writer’s collec- 
tion of H. arhorescens subsp. Swezeyi was fixed 
in a Carnoy’s solution (3 parts absolute ethyl 
alcohol: 1 part glacial acetic acid). All other 
material was prepared from herbarium spec- 
imens as follows. Vegetative and floral parts 
1 Rancho Santa Ana Botanic Garden, Claremont, 
California. Manuscript received February 9, 1956. 
were treated with warm 2.5 per cent aqueous 
NaOH to remove cell contents and expand 
structures to their original condition. Further 
clearing was achieved by treatment with a 
250 per cent chloral hydrate solution. After 
washing, whole mount preparations of flowers 
and leaves were made by dehydration in an 
ethyl alcohol series, staining in a 1 per cent 
safranin solution in absolute ethyl alcohol, 
transferring to xylene, and mounting in xy- 
lene-soluble synthetic resin. Portions of both 
the Carnoy’s-fixed material and the "revived” 
herbarium material were prepared for section- 
ing according to the tertiary butyl alcohol 
schedule of Johansen (1940: 130-131). Treat- 
ment with hydrofluoric acid prior to infiltra- 
tion was necessary for softening woody 
structures. Sections were stained with a 
safranin-fast green combination correspond- 
ing to Northen’s modification of Foster’s 
tannic acid-ferric chloride method ( Johansen 
1940: 92-93). All of the collections for which 
anatomical data were assembled are repre- 
sented in the Bernice P. Bishop Museum in 
Honolulu, except where otherwise noted. 
Duplicates of many of these specimens are in 
other herbaria. 
ANATOMY 
The Leaf 
Examination of young leaves near the 
shoot apex of Hesperomannia arhorescens subsp. 
Swezeyi showed them to be densely covered 
with uniseriate nonglandular hairs (Fig. 1). 
Interspersed among these are biseriate glan- 
dular trichomes. At such an early stage, vir- 
tually every epidermal cell on both surfaces 
207 
