1903] Robinson,— Generic Position of Echinodorus parvulus 85 
The lateness of the season of course gave me an excellent opportu- 
nity to examine the plant in full fruit. After a careful examination 
of many plants I failed to find any trace of that regularity of arrange- 
ment of the achenes on the receptacle attributed to this species 
of Echinodorus in some botanical works. There seems, therefore, no 
cause to refer the species to Alisma, as several authors have done. 
Boston, MASSACHUSETTS. 
THE GENERIC POSITION OF ECHINODORUS 
PARVULUS. 
B. L. RoBINSON. 
(Plate 45, figures 1-10.) 
WHILE examining some excellent material of the rare Æchinodorus 
parvulus, Engelm., kindly placed at my disposal by E. L. Rand, Esq., 
I have had occasion to review the opinions, which have been 
expressed regarding the correct classification of this species, and 
some notes on the subject may be of interest. 
The North American plant bearing this name was originally 
described by Dr. George Engelmann! as “chinodorus subulatus. It 
was so named under the impression that it was the A/isma subulatum 
of Linnaeus,? a species which later proved to be Sagittaria pusilla, 
Nutt. Our little Echinodorus was accordingly rechristened by Engel- 
mann 3 and called Æ. parvulus. The propriety of this change can 
scarcely be questioned when we consider that the earlier name, Æ. 
subulatus, rested upon a confusion of two quite distinct elements, 
namely, the synonym A/isma subulatum and a true Echinodorus. In 
such cases it may be assumed that the status of the combination 
should be determined rather by the name-bearing synonym than by 
the material which was erroneously identified with it. 
Echinodorus parvulus matures about fourteen carpels, which 
being arranged spirally upon a strongly convex receptacle form a 
! Engelm. in Gray, Man. ed. r, p. 460 (1848). 
2 Spec. Pl. i. 343 (1753). 
3 Engelm. in Gray, Man. ed. 2, p. 438 (1856). 
