OBJECT LESSONS IN BOTANY. 



F^g. 76. PotentiUa anaerina ; leaf with five cut lobes, almost quinate. 

 Fig. 77. PotentiUa tridentata ; ternate, with palmate, three-toothed leaflets. 

 Fig. 78. Jeffersonia diphylla ; a hinate leaf. 

 Fig. 79. Lemon ; a simple leaf jointed to the petiole. 



LESSON VIII. 



SESSILE LEAVES— FOEMS OP STIPULES. 



41. "W"e have already stated (Lesson I., § 5) that many 

 leaves are withont petioles (foot-stalks), or, in other words, are 

 sessile. The figures presented on page 33 exhibit some of the 

 modes of attachment peculiar to sessile leaves. In Fig. 80 

 (an Aster) you see leaves of the form called spatulate (Lesson 

 ni., § 5), having large base lobes nearly clasping the stem 

 at the point of attachment. Such leaves are said to be amr 

 pleadcaul (stem-clasping). 



42. In the next figure (81, Bellwort) the leaves are ellipti- 

 cal, parallel-veined, and not only clasp the stem at base, but 

 the lobes there grow together on the opposite side, appearing 

 as if the stem passed through the leaf ; that is, perfoliate. 



40. What kind of venation have all these forms ? On the palmate vena- 

 tion what forma are founded ? 



41. When are leaves said to be seasUe? Define an amplexicaul leaf. 



43. Can you define a perfoliate leaf? 



