THE PLANT BODY 



13 



leaf, are rare; they occur in the Hydrocharitaceae, Butomaceae, 

 Najadaceae, perhaps some of the Dioscoreaceae. The monocotyledons 

 have sometimes been described as lacking stipules, but there is little 

 agreement in the interpretation of the sheathing base of the monocotyle- 

 don leaf. The thin margins are commonly interpreted as representing 



Fig. 3. Sketches of stipules showing variations in type. A, Hamamelis, simple, free; 

 B, Viola, deeply dissected, free; C, Galium, two leaflike stipules with each leaf, free; 

 D, Rosa cinnamomea, leaflike, adnate to petiole. {A-C, drawn by A. List.) 



adnate stipules that have lost identity as such in adaptation to the gen- 

 eral monocotyledon habit of "telescoped shoot." The leaf sheath is also 

 sometimes considered an elaboration of the primordial leafbase, without 

 distinction of blade and stipules. The loose use of the term ligule for the 

 wings of the sheathing leaf adds to the difficulty of interpreting the 

 monocotyledon leaf as a whole. 



Evidence in support of the concept that the stipules form the marginal 

 parts of the sheathing base has been found in those monocotyledons 

 that show paired adnate stipules, especially Totamogeton. In this genus. 



