A Taxonomic Revision of the Hawaiian Species of the Genus Car ex 
Robert W. Krauss * 2 
INTRODUCTION 
Linnaeus published the genus Carex in 
Genera Plantarum, Ed. 1, p. 280, 1737, and 
again in Genera Plantarum, Ed. 5, p. 420, 
1754. The present use of the name is based 
on the latter. The type species for the genus 
has been designated by Mackenzie (1923: 
343 ) as Carex acuta var. nigra L., which has 
been known erroneously for some time as 
Carex Goodenowii J. Gay. Hitchcock and 
Green, however, have listed Carex hirta L. 
in their list of Linnaean lectotypes (Camp, 
1947: 114). The problem of typification is 
still an open one. The genus was recognized 
as a natural group even before the time of 
Linnaeus, but from 1754 to 1915 the group 
was included in different genera in accord- 
ance with various generic concepts, and also 
attempts were made to split the genus into 
segregates. Since 1754 a total of 55 generic 
names has been proposed for the genus or 
its segregates. Nevertheless, it is the con- 
sensus of present-day workers that the group, 
though large, deserves the unity of single 
generic rank. 
In the Hawaiian Islands specimens of 
Carex have been regularly collected by bot- 
anists visiting the islands. The earliest col- 
lection examined for this study is that of 
James Macrae, which was secured on the 
island of Hawaii during the visit of H.M.S. 
"Blonde” in 1825. Since that date collections 
have been deposited in all the major herbaria 
in the world. In spite of the splendid collec- 
L A condensation of a research problem submit- 
ted in partial fulfillment of the requirements for 
the Master of Science degree at the University of 
Hawaii in the Department of Botany, June, 1949- 
2 Department of Botany, University of Hawaii. 
Manuscript received June 20, 1949. 
tions which are available (approximately 600 
numbers were received for this study), no 
monographic study of the Hawaiian carices 
has been made. From time to time species 
and varieties have been described from these 
islands, but often by botanists working far 
from Hawaii and who were using not only 
single specimens but often mere fragments 
of a plant. 
Taxonomic differentiation within the genus 
rests fundamentally on the morphological 
differences in the achene and surrounding 
perigynium. The wide and distinct variation 
of these structures in such a vast number of 
species is remarkable. Identification of the 
species could be effected by reference to these 
structures alone. However, generic group- 
ings which included species with similar pe- 
rigynia but based on other characters — pri- 
marily on the arrangement of spikes and 
inflorescences — have been made. The use of 
such characters is indispensable in breaking 
the genus into smaller groups but the char- 
acters show much intergradation, and their 
use results in the placing together of seem- 
ingly unrelated species so that doubt is cast 
on their being natural groupings. 
In applying the characters needed to de- 
lineate the Hawaiian species, certain consid- 
erations involving the nature of species and 
criteria for their erection or retention in the 
generic population represented in the islands 
must be discussed. The genus Carex, like 
many other genera, has been subjected both 
to extreme division into species and to con- 
servative grouping in large polymorphic or 
perhaps aggregate species. An investigation 
to determine which treatment is nearer the 
truth is not the purpose of this study. The 
recent development of experimental methods 
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