BOT.-VOL. I.] CAMPBELL— SPARGANIUM. 297 



pistil is composed of two completely united carpels, and the 

 resulting fruit is two-seeded. In both of these the style is 

 very short or quite absent and the two stigmas are very long 

 (fig, 4) . The base of the ovary is also less tapering than 

 in S. simplex and the perianth scales are heavier and nearly 

 or quite entire at the apex, 



S. simplex, which was the species principally studied by 

 me, is a wide-spread form occurring throughout the north- 

 ern hemisphere. In California it is confined to the higher 

 mountains, the specimens collected by me being found near 

 Lake Tahoe which has an elevation of over 6,000 feet 

 above sea-level. 



The Staminate Flozver. 



In S. simplex the staminate flowers form dense heads, 

 each flower consisting of about six stamens. Just before 

 the dehiscence of the anthers, the filaments elongate very 

 much, so that the head becomes much looser, and the pollen 

 is readily dislodged by the swaying of the slender filaments, 

 much as in the grasses and sedges. The anther has four 

 loculi as in most Angiosperms and offers no specially note- 

 worthy peculiarities. The other species seem to agree 

 closely in the structure of the stamen and were not crit- 

 ically examined. 



The pollen-spores of S. simplex are small globular cells 

 (fig. 6) and at maturity show the usual division of the nu- 

 cleus into a larger vegetative one, and a smaller generative 

 nucleus, but the latter was not seen to divide again while 

 the pollen remained within the anther. Probably the final 

 division of the generative nucleus takes place within the 

 pollen-tube. Perhaps owing to its small size it was not pos- 

 sible to demonstrate the presence of a definite generative 

 cell, the nucleus apparently lying free in the cytoplasm of 

 the pollen-spore. As the cytoplasm of the ripe spore is very 

 dense and stains strongly, it was not always easy, even in 

 sections, to clearly distinguish the nuclei. The outer spore- 

 membrane is marked with fine granulations but is not very 

 thick. In this species there was almost always present in 



