296 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



In S. sim-plex the lower three or four of these heads 

 develop the pistillate flowers, while the number of staminate 

 heads is usually larger. 



The individual flowers, according to Dietz (1. c), arise 

 as small prominences upon the hemispherical fundament of 

 the inflorescence, and upon these prominences arise sec- 

 ondary outgrowths which develop respectively into stamens 

 or carpels. Dietz does not describe in detail the develop- 

 ment of the stamen, and unfortunately my own material 

 was too old to show this, so that it is not now possible to 

 make a comparison with such Monocotyledons as have been 

 investigated. 



The scales of the perianth arise early, but Dietz does not 

 describe their development. 



To judge from his somewhat brief account and very dia- 

 grammatic figures, the development of the carpel and ovule 

 is much like that of the low types like Zannichellia and 

 Z,?7ce«, which Sfarganiiim resembles in these respects more 

 than it does Typha, with which it has usually been associ- 

 ated. While further investigations are required before this 

 can be decided, it looks as if in Sparganium, also, as in 

 other low Monocotyledons, that the solitary ovule is of axial 

 origin and not a product of the carpel. 



The pistillate flower in S. simplex (fig. i) consists of a 

 single carpel surrounded by about six delicate membrana- 

 ceous scales which form the perianth. Engler (Engler and 

 Prantl, 1889) figures these in this species as having en- 

 tire margins, but the form studied by me had the end of 

 the narrowly spatulate scale sharply toothed (fig. 2), and 

 the most recent figure (Britton and Brown, 1896) of this 

 species shows the same thing, but with fewer teeth than 

 my specimens. A delicate midrib traverses each scale. 

 The ovary in this species merges gradually into the slender 

 style which terminates in the narrowly sagittate stigma 

 which is covered with minute papillae. 



In S. longifolhim, which in many respects resembles S. 

 simplex , Xh^ style and stigma are both shorter. In a second 

 group represented by S. Greenii and S . eurycarpum the 



