Growth dynamics and morphology of annual shoots, according to their architectural position, in young Cedrus atlantica (Endl.) Manetti ex Carriere (Pinaceae)

The influence of shoot architectural position on growth and branching patte rn of young Cedrus atlantica (Endl.) Manetti ex Carriere trees were studied . Extension growth and type of axillary products (lateral bud, sylleptic sh ort or long shoots) of annual shoots of increasing branching order (main st em, branches and branchlets) were recorded weekly during the 1993 growing s eason. Annual final shoot length, duration of extension, and maximum extens ion rate decreased with increasing branching order. Sylleptic axillary shoo ts occurred only on annual shoots of the main stem and branches and were pr oduced when extension rate was at its highest. Differences in growth rate a nd final length of annual shoots, according to their architectural position , were related to differences in the total number and diversity of types of sylleptic axillary shoots produced. It is suggested that types and numbers of sylleptic axillary shoots produced are linked with threshold values for both final length and extension rate of the parent shoot. (C) 1999 Annals of Botany Company.