36 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 30 Ser. 



and more slender leaves and stems, and on closer examina- 

 tion is found to resemble more some of the slender species 

 of Potamogeton. 



The flowering shoots arise from a creeping rhizome, and 

 each node develops two slender, unbranched roots, which 

 finally penetrate the mud and hold the plant firmly in posi- 

 tion. The slender stems are abundantly branching, at least 

 in the specimens examined by the writer. At each node 

 there is an apparent whorl of three leaves, as in Naias, 

 below which is a delicate, membranous, cylindrical sheath, 

 which completely envelopes these in their younger stages; 

 and an entirely similar sheath forms a bell-shaped involucre 

 about the pistillate flower, or, more correctly, inflorescence. 

 The male flower here, as in Naias, is reduced to a single 

 stamen and is borne close to the female inflorescence at 

 each node. Of the three grass-like leaves at each 

 node, the two lower are opposite and have a membra- 

 nous, closed, stipular sheath; the third leaf is above these 

 and the sheath is either wanting or is incomplete. The 

 plants from which the following account was made were 

 collected at Stanford University, in a ditch in which the 

 water is usually running swiftly. Most of the material was 

 collected in the late winter and early spring, but during 

 November and December of 1896 the plant was found with 

 fruit and a few flowers. Ordinarily, however, the plant 

 has been observed only in the early spring months. 



There is much disagreement as to the systematic position 

 of Zannichellia, as we have already intimated. In our 

 American manuals the plant, in common with several other 

 genera, is placed in the family, Naiadacese (Morong, 

 1893 ; Britton & Brown, 1896, p. 79) . In Engler & Prantl's 

 " Natiirliche Pflanzenfamilien " the family Naiadaceae is 

 made to include only the single genus Naias, and Zanni- 

 chellia is placed in the Potamogetonaceae, but forming a 

 special subfamily Zannichelliae. Schumann (1892), who 

 has made the most recent study of the genus, considers it to 

 be sufficiently distinct from the other Potamogetonaceas to 

 rank as the type of a separate family, Zannichelliaceae, in 



