IO PART I. — ORGANOGRAPHY. 



Fig. 9 represents a twig of the Ohio Buckeye as it appears in 

 the late autumn or early spring. At the apex is a large scaly bud; 

 below, situated in the axils of leaf-scars, are 

 smaller axillary buds. Fig. 10 is a longitudi- 

 nal section of one of the large terminal buds 

 of the same tree, showing the very short axis 

 and compactly arranged leaf-rudiments. 



Buds normally occur as represented in 

 Fig. 9, either at the ends of the stems, when 

 they are called terminal buds, or in the axils 

 of leaves, when they are called axillary buds; 

 sometimes, however, they occur in other 

 situations on the stem, and occasionally they 

 are found on roots or even on leaves ; in all 

 these cases they are termed adventitious buds. 



Examples of buds of this kind occur 

 occasionally on the American Elm when 

 the surface of the stem has been abraded 

 or irritated, causing an extra supply of nour- 

 ishment to flow to the spot ; the compact 

 bunches of twigs sometimes seen on these 



tree, showing the manner 



trees originate from such buds ; the shoots in which the scales over- 

 which often arise in great numbers from the 

 trunk of a pollarded willow have a similar origin ; the leaves of 

 Bryophyllum, when they have been shed, habitually produce 



Fig. 



Fig. 



Fig. q. — Portion of twig 

 of Ohio Buckeye, natural 

 size, with terminal and 

 axillary buds, and leaf- 

 scars, 



Fig. 10. — Enlarged view 

 of longitudinal section of 

 a terminal bud of the same 



Fig. 11. — Leaf of Bryophyllum, with marginal buds. 



marginal buds that, under favorable conditions, root and form 

 new plants (see Fig. 11), and the occurrence of adventitious 

 buds on the roots of some species of Poplar, causes them habit- 

 ually to send up shoots at a distance from the main trunk. 



