SECTION K.— BOTANY. 



THE GROWING TREE 



ADDRESS BY 



PROF. J. H. PRIESTLEY, D.S.O., B.Sc, 



PRESIDENT OF THE SECTION. 



Contents. 



The Habit of Growth of the Tree. 



Apical Growth and Radial Grmvth. 

 Basipetal Cambial Activity from the Buds. 



I. Form. 



Branching in Softwood and Hardwood Trees. 



II. Structure. Cambial Growth and Vascular Differentiation 

 in Softwood and Hardwood. 

 Cambium and Vascular Differentiation in the Softwood. 

 Cambium and Vascular Differentiation in the Hardwood. 



III. Function. The Movement of Water and Solutes in the 



Tree. 

 Water Movement at Bud-break. 

 Water Movement into the Expanding Foliage. 

 The Contents of the Wood. 



Air. 



Water. 



Water Vapour. 

 Sap Wood and Heart Wood. 

 The Ascent of Sap. 

 The Movement of Organic Solutes. 



Trees do not form a special botanical category ; they are often regarded 

 as the special study of the forester rather than of the botanist, and they 

 seem never to have formed the special subject of a presidential address 

 in this Section. In 1894, however, when Prof. I. Bayley Balfour 

 presided over Section D, upon the last occasion on which that Section 

 included botanists as well as zoologists, forestry was the subject of his 

 address. 



In making this his theme before a gathering of biologists, he laid 

 emphasis upon the fact that the ' utilitarian side gave the first impetus 

 to the scientific study of botany,' and that botany still had, in agriculture 



