84 • The Ohio Naturalist. [Vol. IV, No. 4, 



striking agreement of some of the leaf forms, and the general 

 character of the flowers at once suggest the Helobiae 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 Monocotyls. 



Since there has been a strong tendency to read Dicotyl charac- 

 ters into the flowers of some water lilies, the writer took the 

 opportunit_v to make a study of the flower of a few representative 

 species of Naiadales and Nymphaeaceae in order to see how well 

 the floral plan could be made to fit into the Monocotyl scheme. 

 It is certainly nuich easier to read Monocotyl characters into the 

 flowers than Dicotj-l. The mere position in which a species is 

 placed may have much to do with its description. For instance, 

 the perianth of Nymphaea advena is described as having six 

 sepals and an indefinite number of stamen-like petals. These 

 staminodes, the so-called "petals," are so evidently only very 

 slightly modified stamens that in many cases a superficial exami- 

 nation will not distinguish them. The perianth is then typically 

 trimerous with three sepals aud 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) 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 Nymphaea 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 Helobiae as in the various 

 species of Potamogeton (Fig. 9). 



The transition from comparatively simple flowers to those with 

 great numbers of parts as appears in ])assing from Cabomba to 

 Nymphaea is al.so 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 al.so a prominent character in various Helobiae as in 

 Sagittaria rigida, Vallisneria, Philotria, I^utomus, and L,innio- 

 charis. 



