342 



ECOLOGY 



adventitious roots are not formed ; the leaves arise in five 

 rows as before, but being illuminated on all sides the bases 

 do not bend, and the blades are not all directed to one 

 side (Fig. 222, 3) ; they are also smaller and simpler in 

 outline. In October or November these shoots produce 



Fig. 222. Ivy. 1, climbing shoot ; 2, section through leaf-base, 

 showing embedded bud; 3, flowering shoot; 4, flower-bud; 5, 

 flower seen from above ; 6, flower in side view ; 7, vertical section 

 of flower ; 8, fruit ; a.r, groups of adventitious roots ; b, bud ; 

 d, disk ; Lb, leaf -base ; p, petals ; s, sepals ; st, stem. 



umbels of flowers (3), which possess several peculiar features. 

 Often one or two flowers are formed before growth of the 

 umbel ceases, and these are left behind on the axis. The 

 flowers (4, 5, 6, and 7) have five sepals, which are so small 

 that the five green petals which protect the inner organs 

 may be mistaken for a calyx ; five stamens alternate with 



