Development of long-shoot terminal buds of western white pine (Pinus monticola)

Publisher Website
Google Scholar
Abstract
Long-shoot terminal bud (LSTB) development in western white pine (Pinus monticola Dougl.) was studied throughout the annual growth cycle to determine the phenology of LSTB development and the time of cone-bud differentiation. Development of LSTB began in early April and cataphylls were initiated from mid-August until early November. Cataphyll initiation was slow during May and June when shoots were elongating and then rapid just after shoot elongation was completed. Proximal cataphylls were sterile, whereas more distal cataphylls began to initiate axillary buds by late June or early July. Axillary buds were initiated first in the proximal portions of the LSTB and then acropetally in rapid succession. The last cataphylls to be initiated in the fall remained as sterile bud scales enclosing the LSTB apex. Axillary buds initiated sterile cataphylls which functioned as bud scales. The number varied with the type of axillary bud. Proximal axillary buds initiated few cataphylls and began to differentiate into dwarf shoots or pollen cones in August. The more distal axillary buds differentiated into dwarf shoots during September and October, The most distal axillary buds initiated many cataphylls during September and October but did not differentiate into seed-cone buds or lateral branch buds until after winter dormancy. Consequently, attempts to induce or enhance seed-cone production in P. monticola would probably be most successful in the spring when seed-cone buds differentiate. LSTB bearing seed cones were larger, had broader apices, and produced more cataphylls during the growing season than did LSTB bearing pollen cones. The phenology of LSTB development in soft pines and hard pines is discussed in relation to reports available on the association of cone crops and climatic conditions in several species of Pinus.

This publication has 1 reference indexed in Scilit: