Ruppia maritima L.

OCCASIONAL PAPERS
OF
BERNICE P. BISHOP MUSEUM
HONOLULU, HAWAII
Volume XV	December 22, 1939	Number 16
A New Variety of Ruppia maritima
(Ruppiaceae) from the Tropical Pacific
By
HAROLD ST. JOHN AND F. RAYMOND FOSBERG
Bernice P. Bishop Museum
and
University oe Pennsylvania, Philadelphia, . Pennsylvania.
In their monograph of the Potamogetonaceafe Ascherson and
Graebner (Engler, A., Pflanzenr. IV, fam. 11:145, 1907) doubtfully
referred the Polynesian material of Ruppia maritima to subsp. rostel-
lata Koch. Later Fernald and Wiegand (Rhodora 16:125, 1914)
presented a more usable treatment with an adequate key. They con-
sidered the plant to be of varietal rank and indicated that in this
category the correct name was var. rostrata Agardh, but they cited no
specimens from the tropical Pacific.
When we have tried to identify the form of Ruppia maritima that
occurs commonly in brackish ponds and estuaries in the Hawaiian
islands, we have found that neither revision contained any variety
identical with our plants. These seem, in some respects, intermediate
between var. rostrata and var. obliqua, having the body of the fruit
less asymmetric and the beak usually shorter than that of the former,
but the fruit more asymmetric and more strongly beaked than that
of the latter. Several other minor and more or less constant differ-
ences are indicated below.
A study of the specimens in the Gray Herbarium annotated by
Fernald and Wiegand as var. rostrata shows that in the vast majority
the fruits are conspicuously asymmetric, much more so than in the
Pacific material, and that the beak, usually somewhat more prominent,
*TT©	*
HAWAIIAN ISLANDS
OAHU
#108
Ruppia maritima	,
Kuapa Fond AoaJtiU'
Kofco Head	^f
Niadaoeae
Collected by Jjydia Moo
K* Nitta
2/S8/3Ö
04281406