Leader Growth of Young Pitch and Shortleaf Pines

Publisher： Society of American Foresters

ISSN： 0015-749X

Source： Forest Science, Vol.9, Iss.3, 1963-09, pp. : 344-353

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Abstract

Seedlings of Pinus rigida Mill. and P. echinata Mill, in New Jersey display highly synchronized leader elongation, often involving the formation and elongation of several buds. Winter buds of these two species are often multinodal. Initially, leader elongation is due to the extension of the basal internode of the winter bud. Subsequently, the succeeding higher internodes elongate. Each internode displays a sigmoid growth curve achieving its peak growth rate after the internode below it. As the winter bud extends, its apical meristem is reactivated, and a new terminal bud formed. In P. rigida seedlings this bud occasionally elongates to form a summer shoot. Open-grown P. echinata seedlings almost always develop one summer shoot, and many produce two.