137 
Three species of Ruppia. 
By J. O. Hagström. 
The authors are not agreeing in the question whether 
we have only one species of Ruppia with many varieties 
or more species. Scandinavian and Danish authors have 
supposed the latter to be the fact. Thus C. Raunkicer , for 
instance, speaks of three Danish species: R. spiralis, rostel- 
lata and brachypus (l.m). L. Schlegel, in 1889, admits two 
Swedish species: spiralis and maritima with a subspecies 
brachypus (2,56—57), later on he also ranks the last mentioned 
as a true species ( 3 , see). A. Blytt agrees with Schlegel in 
his earlier exposition ( 4 , 51). The Englishman Ar. Bennett 
says: species 1 or more? or many subspecies (5,224). Brit- 
ton & Brown in their Illustrated Flora of the northern 
United States etc., 1896, 78—79, suppose 3 à 4 species, of 
which two North American: maritima and occident alis. To 
those Rydberg (6,1s) has laid R. pectinata and Nelson 
R. curvicarpa (7,122). But Robinson and Fernald record 
only Ruppia maritima (8,7s). German authors, K. Schumann 
(9,i4i), P. Ascherson & P. Graebner (10,356) and P. Graeb- 
ner (also in the year 1907) assume but one species with 2 
subspecies and, for the rest, many forms of lower rank 
( 11 , 142 — 145 ). 
At the lirst glance the European forms, certainly, 
seem to be rather similar to one another, especially with 
regard to the stem and foliage. By closer examination of 
the leaves, however, there is the same difference between 
R. maritima and spiralis as between Potamogeton pectina- 
tus and filiformis. This has obtuse leaves and that acute. 
For the rest the leaves are, outwardly observed, rather the 
same. The appearance of the leaf- apex is specific in Po- 
tamogeton and so it is also in the genus Ruppia. The pe- 
duncle is different, depending on different biological facts: 
Bot, Not. 1911. 
