200 



PHIX.OSOPHICAL NOTES ON 



In Potamogeton heteroplyUus (Fig. 57) we have bud-scales 

 which might also be considered stipules. 



In Potamogeton natans (Fig. 58) we find a similar variety of 

 well developed bud-scales, some of which might well be stipules. 

 "We see an independent stipule («), a stipule adnate to the petiole 

 (ft), and a third stipule vaginating the main stem (c). This 

 figure does not show clearly whether {h) is adnate to or 

 independent of the petiole. 



Fig. 58. Stipules of Votamogeton natans, Lin. (Syme, "Br. Bot.," pi. 1399.) 



Anyhow, the three following species of Potamogeton^ shown 

 in Figs. 59, 60, and 61, do not leave us in doubt regarding the 

 orio-in of the vagina and ligule of grasses. Whether the vagina 

 comes from one or two stipules is not perhaps easy to make out, 

 nor is this of much importance, considering that some species in 

 the genus Ficus have two, and some have only one ; but what is 

 not difficult to make out is that the vagina of grasses is the 

 adnation of a stipule to the leaf petiole, and the ligule only its 

 free ends. 



