Grossenbacher—Radial Growth in Trees. 
7 
species he says that root growth had also “ started more or less 
in advance of the buds:” Picea excelsa, P. alba, P. pungens, 
Pseudotsuga Douglasii, Abies concolor, Thuja occidentalis, Finns 
sylvestris, Tsuga canadensis, Tamarix amurensis, Acer sacchari- 
num, Pyrus Mains, P. Communis, Prunns cerasns, P. virginiana, 
Betula alba, Morns alba, Cornns stolonifer, Eleagnns hortensis, 
Ribes nigrum and R. oxyacanthoides. "When these observations 
are compared with those of von Mohl 15 who found that, though 
radial growth in conifers has practically ceased by winter and 
that in deciduous trees it usually has not, it seems likely that Goff 
overlooked the possibility that portions he held to be new spring 
growth may have been very late growth of the preceding fall. 
Hartig 16 found that the roots of various forest and fruit trees 
had ceased radial growth in January, as judged by the thickness 
of the new ring and by the presence of starch in all of the ray 
cells of the cambial region. Russow 17 made similar observations 
in regard to both forest and fruit trees. Hartig notes an excep¬ 
tion in the case of a species of willow where radial growth of the 
roots had not been completed as shown by the thinness of the 
ring as well as by the absence of starch in the ray cells of the 
cambial region. Resa 18 also made some observations which sup¬ 
port Goff in some cases at least. He found that the roots of 
Picea and Fagus ceased growth in November and recommenced 
in February and March, while in case of Aesculus Hippocastan- 
um and Tilia root growth ceased in October and recommenced 
in December or later. In Alnus glntinosa root growth began in 
October and continued practically through the winter except 
when the ground was frozen. Root growth began in late May in 
Acer campestre and in June in Qnercus Robur. It is not usually 
considered that such enormous variations occur in the root 
growth of our trees and shrubs and for want of more detailed 
information it seems necessary to admit that at least in some 
16 von Mohl, H. Einige anatomische und physiologische Bemerkun- 
gen uber das Holz der Baumwurzeln. Bot. Zeit. 20:225-30; 233-39; 
268-78; 281-87; 289-95; 313-19; 321-27. 1862. 
16 Hartig, Th. Ueber die Zeit des Zuwachses der Baume. Bot. 
Zeit. 21:288-89. 1863. 
17 Russow, E. uber den Inhalt der parenchymentischen Elemente der 
Rinde vor und wahrend des Knospenaustriebes und Beginns der Cam- 
biumthatigkeit in Stamm und Wurzel der einheimiscben Lignosen. 
Stizungsber. Naturforscher-Ges. 6:386-88. 1884. 
18 Resa, F. Ueber die Periode der Wurzelbildung. Inaug. Dissert. 
Bonn. 1877. pp. 37. 
