VEGETATIVE PROPAGATION OF WHITE PINE 



By William L. Doran, Research Professor of Botanyi 



The white pine, Pinus Strobus L., is the most important timber tree in Massa- 

 chusetts as indeed it has been since the early days of Plymouth Colony. It is 

 also much planted for the protection of watersheds and reservoirs, is a good tree 

 for windbreaks, and, being highly ornamental, is useful in horticulture or the 

 improvement of the landscape. But, as is frequently observed by woodsmen and 

 others, individual white pine trees in nature differ markedly, some being highly 

 desirable from the viewpoint of forestry, others much less so or not at all. 



The growth of white pine and consequently the type of tree is of course affected 

 by the environment, e.g., light or the lack of it and the character of the soil. 

 Silvicultural methods by which some of these differences may be corrected do 

 not, however, come within the province of the work here described. 



The present study is concerned with other differences which are apparently 

 inherent in the tree, for, under the same or very similar environmental condi- 

 tions, individual white pine trees of a given age may differ in rate of growth, 

 height, spread, straightness, branching habit, general outline, type of foliage, 

 and susceptibility to disease. 



When pines possessing certain desirable characteristics are found in nature or 

 result from tree breeding projects (25)^, they may be worth perpetuating, re- 

 producing in exact detail. For this, reproduction by seeds is undependable, 

 since the progeny or some of the progeny may be quite unlike the parent tree in 

 form or behavior. For example, trees grown from seeds of a white pine immune to 

 blister-rust'^ were not themselves immune to that disease (16). But the white 

 pine or some white pines are reproducible by cuttings; and, as with many other 

 woody plants thus vegetatively propagated, members of the resulting clone, 

 progeny of a single tree, may be expected to be identical or practically identical 

 with each other and with their parent in form and behavior. 



Some of the more abnormal forms of white pine, although useless as timber, '•* 

 are nevertheless useful in ornamental horticulture; and these too are reproducible 

 in every character, not by seeds but vegetatively b}' cuttings. 



A normal white pine may grow two to three feet in a season when young. The 

 horticultural varieties minima Hornibr. and umbraculifera Carr. grow only about 

 one to two inches a year — white pines botanically, but more like bushes or 

 shrubs than trees (11, 21). Other interesting dwarf white pines for ornamental 

 planting are the varieties radiata Hornibr., a shrub wider than high; var. pumila 

 Beiss., three feet in height when three feet through; var. pendida Beiss., a round- 

 ish bush with pendulous or weeping branches (11); var. prostrata Masters, a 

 decumbent or creeping form with trailing branches (1, 11, 21); and var. nana 

 Knight, a short-leaved flat-topped bush (1, 11). The variety fastigiata has 

 ascending branches forming a narrow pyramidal head (21). Other varieties 

 differ from ordinary white pines in the color of the foliage; the leaves of var. 

 glauca are light bluish green (21), those of var. aurea are yellowish, and those of 

 var. nivea Booth and Knight are short and silvery-white beneath (1). 



Certain conifers, e.g., yews, arbor-vitae, some of the junipers, and some cj'pres- 

 ses (Chamaecyparis), are readily propagated by cuttings. As compared with 



■'The writer gratefully acknowledges the interest and cooperation of Professor R. P. Holdsworth, 

 Head of the Department of Forestry, in this work. Professor Holdsworth, with clonal differences 

 in mind, furnished the material from which cuttings were made and he has planted rooted cuttings 

 in the college forest lor subsequent observation as to survival and growth. 



^Numbers in parentheses refer to literature cited. See pages 15 and 16. 



^Caused by the fungus Cronartizim rihicnla Fischer. 



