273 

 THE GROWING TREF. 



(Continued from p. 259, rnit XLMII.) 



E. -Nanism. 



Nanism or dwarfing may arise from more tiian one cause., or from a combination 

 of them. As a rule, the most obvious factor is prevalence of strong winds, and where 

 this is accompanied by shallowness of soil, we have a couple of important factors. It 

 is notorious that trees become dwarf in exposed situations near the sea, and on high 

 mountains; indeed, we can trace the diminishing size of a species according to the 

 varying shelter individuals receive. 



Examples of the effects of the strong sea air in diminishing size, taken almost 

 at random, are, at First Point, near Kincumber. Broken Bay, New South Wales, where 

 Mr. R. H. Cambage and I saw E. resinifem 8m. flowering at 4-5 feet, E. umbra R.T. 

 Baker at 4-5 feet, E. patiiculala Sm. at 6 feet. Normally these species are medium-sized 

 to large trees. 



F.— The Flowering of Eucalypts while in the Juvenile-leaf Stage. 



'■ The generative maturity of plants is not connected inunutably \A'ith a definitive 

 stage of development." There seem so many cases in which" flowering and fruiting 

 have been found to occur in the opposite-leaved stage that it seems fair to assume 

 that further experience will show that it may occur in very man}- more — perhaps in 

 all species. 



Naudin's First Memoir, 347 (1883) says, after speaking of the adventitious 

 leaves '" which take on the appearance of the juvenile stage. . . ," '"' this 

 retrogression towards anterior forms, and ■which is like a partial rejuvenation of the 

 tree, is not an obstacle to the flowering; these branches of juvenile aspect sometimes 

 flower and ripen the fruits as well as those of the adult form." He seems to have been 

 the first botanist who made this observation. 



In 1906 Dr. L. Diels published his "■ Jugendformen und Bliitenreife iju 

 Pflanzenreich,'" and I camiot do better than quote portions of a review of it by C. E. 

 Barnes which appeared in the Botanical Gazette, vol. 45, p. 137 (February, 1908). The 

 work deals, i)iter aUa. with the cpiestion of precocious blooming, and the genus Eucalj'ptus 

 is illustratively employed. 



An interesting discussion of the relations between the vegetative form and the tioweriua period of 



plants is presented by Dr. Diels. . . . The queitions with which the book deals were raised bv the 



author's travels in West Australia in 1902. After his return he examined the literature, and made further 



inv,^;t.igat.ions to throw light ui-ion the ]iroblenis of form in tlie plant kingdom. He has gathered toffether 



C 



