S2 



OBJECT LESSONS IN BOTANT. 



F%g. 76. Potentilla anserina ; leaf with five cut lobes, almost quinate. 

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

 Fig. 78. Jefi'ersonia diphylla ; a binate leaf. 

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



LESSON VIII. 



SESSILE LEAVES— FORMS OF STIPULES. 



41. We have already stated (Lesson I., § 5) that many 

 leaves are without 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 

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

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

 'plexicaul (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 ; tliat is, perfoliate. 



40. What kind of venation have all these forms ? On th.e palmate vena^ 

 tion what forms are founded ? 



41. Wlien are leaves said to be sessile? Define an amplexicaul leaf. 



43. Can you define a perfoliate leaf? 



