84 
The Ohio Xaturalisf. 
[Vol. IV, Xo. 4 , 
striking agreement of some of the leaf forms, and the general 
character of the flowers at once suggest the Helol)iae as near rela- 
tives ; and though such characters could not be of first rank in 
making a final disposition of the group, they do not in the least 
stand in the way but rather assist in disposing of the water lilies 
as Monocotj’ls. 
Since there has been a strong tendeuc}' to read Dicot\ l charac- 
ters into the flowers of some water lilies, the writer took the 
opportunit\' to make a study of the flower of a few representative 
s]:>ecies of Xaiadales and Xymphaeaceae in order to see how well 
the floral plan could be made to fit into the Monocotyl scheme. 
It is certainly much easier to read Moiiocotyl characters into the 
flowers than Dicot}’!. The mere position in which a species is 
placed may have much to do with its description. For instance, 
the perianth of Xymphaea advena is de.scribed as having six 
sepals and an indefinite number of stamen like petals. These 
staminodes, the so-called “petals,” are so evidently only ver}- 
slightly modified stamens that in many cases a superficial exami- 
nation will not distinguish them. The perianth is then typically 
trimerous with three sepals and three petals. This is of course 
of no special importance, for many of the true Ranales also have 
a trimerous perianth. 
In Castalia the sepals are said to be four and the petals numer- 
ous. This is sometimes the case ; but in Castalia odorata (Fig. 
II j the sepals are normally three in a cycle, but sometimes by 
the expansion of the receptacle one of the segments of the second 
cycle is partly or nearly completely brought to the outside. Its 
relationship to the inner cycle is, however, always evident. The 
second cycle of three segments usually with some green on the 
outside, must therefore be regarded as corresponding to the sec- 
ond cycle in Cabomba or Xymphaea and all the rest of the petal - 
like segments may be staminodes. In Castalia tuberosa (Fig. 12) 
the dispacement by expansion is normal and there are four green 
.segments, but the one “.sepal” still clearly shows its relation to 
the inner cycle. This tendency of the floral organs to fall into 
sets of four is very prominent in some Ilelobiae as in the various 
species of Potamogetou (Fig. 9). 
The transition from comparatively simple flowers to tho.se with 
great numbers of parts as appears in passing from Cabomba to 
Xymphaea is also characteristic of the Alismaceae. The extreme 
numbers no doubt represent multiplication or augmentation. In 
Alisma the parts are few (Fig. 2), in Sagittaria rigida ( Figs. 3, 
4 ) the numbers are greater, but still small when compared with 
the carpellate flowers of Sagittaria latifolia, where the carpels 
count up to sixteen hundred, more or less (Figs. 5, 6). Stamin- 
odes are also a prominent character in various Helobiae as in 
Sagittaria rigida, Vallisneria, Philotria, Putomus, and Limno- 
charis. 
