ON NA1AS GEAMINEA DEL., VAE. DBLILBI MAGNUS. 



17 



Fig. 74. 



XI. — The Antherifebous Flowee. 



The male flowers are not so numerous as the female flowers, 

 and they grow intermixed with them. Although I have frequently 

 found plants of Naias graminea in which none but pistilliferous 

 flowers could be detected at the period of examination, such ten- 

 dency towards dioecism never showed itself when anther-bearing 

 flowers were present. When the latter occurred on a plant 

 pistilliferous flowers were invariably present, and oftener than not 

 side by side with them (see figs. 67 and 68). 



My observations of the anther do not quite coincide with the 



descriptions and figure given by Dr. Magnus ; I have consequently 



given a larger number of illustrative drawings of these organs. 



The drawing of Dr. Magnus is reproduced on Plate 252 in fig. 35. 



When young they are oval-shaped bodies borne - upon 



a very short stalk (see figs. 74 and 76). So much do they 



resemble the anther of an ordinary flowering-plant that 



I was a long time in realising that the outer body which 



I was examining was the membrane which formed the 



perianth. The perianth closely invests the anther 



throughout all its stages of growth, and, from all that 



I have seen, it keeps pace uniformly with the growth of 



the membrane of the anther. 



The anthers of this genus, according to Dr. Magnus, • 

 are axis-growths which, when ripening, are pushed 

 through the perianth, rupturing that membrane some- 

 what irregularly, and they finally dehisce at their apex. 

 That the anthers, of the Eeddish plant dehisce at the 

 apex there is no doubt, but I have seen no trace of the 

 rupturing of the outer perianth-membrane through the 

 emergence of the anther proper ; on the contrary, the 

 summit of the flower presents a regularity of parts for 

 which Dr. Magnus's observations did not prepare me. 

 The rupturing of the perianth in N. major is shown in 

 figs. 22 and 28 on Plate 251. 



In an early stage the antheriferous flower of N. 

 graminea has its outer membrane prolonged into two 

 erect rounded ears, which are continued down the sides 

 as keels or ridges (figs. 67 and 75). The young pollen 

 at this stage is distinctly seen through the membranes of 

 the flower and of the anther (fig. 76). The anther then 

 becomes more elongate by its upward growth ; a slight 

 groove makes its appearance longitudinally, corresponding 

 with the principal dissepiment of the anther (fig. 68) ; the upright 

 ears and the keels lose their prominence, and the separate pollen- 

 grains are not so distinguishable (fig. 77). Finally, the mature 

 quadrilocular anther is an ovoid cylindrical body having two narrow 

 ridges covering the summit, and descending about half-way down 

 the covering of the flower (fig. 78). For comparison, see an 

 antheriferous flower of N.. minor in Plate 251, fig. 17 ; a transverse 

 section of N. major in fig. 18 ; a vertical section of N. major in 



Fia. 75. 



Fig. 76. 



