1918] Fernald,— Character of Vallisneria americana 109 
Examination of European specimens and of European plates shows 
at once that, as would be expected, there is a very definite difference 
between the European and American plants. In the staminate in- 
florescence the pouch or spathe of the European plant, as shown in all 
good European specimens and illustrations, is borne upon a slender 
filiform scape, which in maturity is 1.6-7 cm. long and only 0.5-1.2 mm. 
thick, and the spathe itself is ovoid, strongly rounded at base and only 
6-9 mm. in length. The staminate spathe in the American plant is 
often nearly sessile, but more often on a short club-shaped thick scape 
0.2-2 em. long and 1.5-3 mm. thick, the spathe itself being much larger 
than in the European, 1-1.6 cm. long, and narrowed gradually into 
the thick scape. This pronounced difference in the staminate in- 
florescences is constant in all material examined which has been in 
condition to display the character, although definite diagnostic 
characters in the pistillate flowers and fruit have not been found. It 
would seem, however, in view of the striking differences in the stami- 
nate inflorescences, that we should recognize Vallisneria americana 
Michx. as the common American plant. 
Very recently Rydberg! has revived V. americana, but not in the 
sense of the present writer, for Rydberg has treated the common 
North American plant as quite identical with the European V. spiralis, 
citing various European illustrations as representing it and treating 
V. americana as a local species found from “Florida to Mississippi” 
with the type locality “Mississippi River.” Rydberg attempts to 
separate the southern plant, which he calls V. americana, from the 
widely dispersed species on the following characters: 
Stigmas 2-cleft for less than half their length; sepals 2-3 mm. long; pistillate 
peduncles usually spiral-twisted in fruit; leaves 3-8 mm. wide. 
1. V. spiralis. 
Stigmas 2-cleft to near the base; sepals 5-6 mm. long; pistillate peduncles 
scarcely spiral-twisted in fruit; leaves 6-20 mm. wide...2. V. americana. 
The writer has not seen sufficient material from the Gulf States to 
feel confident that the stigma-characters indicated by Rydberg are 
important, but such material as he has before him shows a plant from 
Florida (Hitchcock, no. 376) with sepals only 3.5 mm. long (instead of 
5-6 as Rydberg requires for the Florida plant) and material from 
Mississippi (Skehan) with leaves 5-7 mm. broad (instead of 6-20 mm. 
as required of the Mississippi plant by Rydberg), while among the 
1 Rydb. N. A. FI. xvii. 68, 69 (1909). 
