DISGUISilS OF LEAVES, CONCLUDED 103 



foliar leaves to spines. The spines are mostly 

 three -branched, as in the illustration, but they 

 are sometimes forked, and often simple. The 

 three-parted spines of the Eussian thistle (Fig, 

 100) may also be interpreted as leaves, because 

 the flowers and branches arise from their axils. 

 The spines in Fig. 98 are branches, however, be- 

 cause they are borne in the axils of the leaves; 

 but a supernumerary bud produces the flowers. 



112a. Is the barberry leaf simple or compound ? Look for a 

 joint near the base of the petiole, and compare with the orange 

 in Fig. 97. Some kinds of barberries have pinnate leaves. 



Suggestions. — The pupil should give particular attention to spines 

 apd thorns, and endeavor to interpret them as suggested above. 

 He should visit bushes of the common wild hawthorns (often known 

 as thorn-apples) soon after growth begins in the spring, and watch 

 the development of the spines. He should look for any evidence 

 of leaves. Any thorny tree or bush will repay an inquisitive 

 visitor at any time of the year. 



XIX. DISGUISES OF LEAVES, CONCLUDED 



113. The common asparagus is shown in Fig. 

 101. The specimen at the left represents the tender 

 shoot, which we eat. The scales should be called 

 leaves or bracts, as may be seen by their phyllo- 

 taxy and by the fact that branches later spring 

 from their axils (a, a). Let the pupil examine 

 an asparagus plant in "full leaf," and notice that 



