INTRODUCTORY LESSONS. 



xix 



base of the leaf. Fig. 40 represents a pinnately lobed leaf; Fig. 43, 

 palmately lobed. When leaves are deeply lobed, as in Figures 41 and 44, 

 they are said to be Parted. Divided leaves are cut quite to the midrib if 

 pinnately divided, or to the end of the petiole when palmately divided. 

 Cleft leaves have the sinuses between the lobes sharp as in Fig. 38. When 

 leaves are pinnately cleft about half way to the midrib they are said to be 

 Pinnatifid. If the lobes are pinnatifid it is described as Bipinnatifid. It 

 is common to give the number of lobes in the descriptive phrase, as pin- 

 nately nine-lobed (Fig. 40); pinnately eleven-parted (Fig. 41); palmately 

 five-lobed (Fig. 43); palmately five-parted (Fig. 44). 



Compound Leaves have distinctly separate leaflets usually jointed 

 to a common petiole, just as simple leaves are jointed to the stem. A leaf 

 is Pinnate, when the leaflets grow 

 along opposite sides of the petiole 

 (Fig. 42); Palmate^ if they all grow 

 from the end of the petiole (Fig. 

 46). Fig. 45 represents a pi/mateZ?/ 

 S-/uliolate leaf; Fig. 46, palmately 

 S-/oUolale. When there is no odd 

 leaflet at the end the leaf is ab- 

 ruptly pinnate. Leaves may be 

 ivnce, thrice, etc., compound, that 

 is, the leaflets may be compound 

 as in some acacias. 



Bracts are leaves among flow- 

 ers, or small undeveloped leaves 

 unywhed'e on the stem. 



45 46 



StlVUleS may be adnate to 45. Plnnately S-follolate leaf of Bur-clover, with 

 , , ', , "^ . , . , gmall stipules. 46. t'almatelyordigltately3.foliolat« 



the base of the petiole, as in the leaf of a true clover, the broad aUnate stipules lacerate. 



rose and clover (Figures 45, 46); they may grow on the stem; or, as in 

 some plants of the Buckwheat Family the stipules form a sheath surround- 

 ing the stem at the base of the petiole. Do not mistake the first leaves 

 of a growing axillary bud for stipules. 



Venation of Leaves. All the leaves thus far described are said 

 to be Netled-veined or Reticulated, because their skeletons of wood fiber 



