264 OBSERVATIONS ON THE 
described a Z. digyna, which had been communicated to him by M. 
Gay. We are also indebted to Reichenbach (Plant. Crit. vol. viii, 
and Fl. Genn. Ewe. t. i, p. 7) for two other species, the Z. gibbe- 
rosa and pedunculata, besides a Z. major, Benngh. which is not 
indicated under that name in the Flora of Munster. 
In the midst of this increase of fallacious riches, the primitive spe- 
cies have been most completely forgotten; the one of them has en- 
tirely disappeared, and the other has become a doubtful plant with 
those who have been skilful in distinguishing the new ones, for of Z. 
palustris Reichenbach says, “ species ex iconibus cognita, cetera 
dubia.” The confusion is greater still among those who believe that 
they are acquainted with it. Indeed, the instant we distinguish two 
species, we must adopt the names of Willdenow, because both the 
descriptions of Micheli begin with the word palustris. Now the Z. 
palustris, W. is most generally that which has been described as a 
new species, whilst the name has been reserved for the Z. dentata ; 
these errors having proceeded from the total neglect of the study of 
the floral organs, and from the characters having been sought for 
only in those of the vegetation, but more especially in the carpels. 
The negligence in this respect has been so great that in the recent 
Genera (the authors having probably had at their disposal only one 
of the species) the anthers are described as two-celled, so that, on 
studying some specimens from Barbary, I at first imagined that I had 
established a new genus; and it is to the kindness of M. Gay that I 
am indebted for an interesting observation which has guided me to 
the truth. 
The organs of vegetation can furnish only very uncertain charac- 
ters, every one being well aware how greatly aquatic plants vary in 
this respect, according as the water is running or stagnant, fresh or 
salt, deep or shallow, &c. The Z. major is distinguished by a more 
vigorous appearance and more highly developed stipules ; but the cha- 
racter of the fruit, which ought to coincide with this appearance, 
seems by no means constant, at least, in some specimens, certainly as 
strong as the Potamogeton pusillus, which I have examined ; and as 
to the character of the leaves being almost always in threes,* it by no 
means distinguishes this variety, for it is souuily found in the 
others.t 
* “ Folia fera semper terna, Reich.” 
+ Weare indebted to M. Maire for the discovery of Z. major in the envi- 
rons of Paris. He has also found it at Montmorency. 
