The formation of heterogeneous storeys in the cambium on the example of Laburnum anagyroides Medik

Anna Wilczek

doi:10.5586/aa.2012.057

Abstract

The formation of the storeyed pattern of cambium in the first two years of cambial activity and the structure of mature cambium was examined in <i>Laburnum anagyroides</i>, a decorative shrub growing in temperate climate. A distinct storeyed pattern was observed in two-year-old stems, despite the presence of tall rays. The heterogeneous nature of storeys was revealed by the analysis of i) the number of fusiform initials forming storeys or groups of packets; and ii) the frequency of anticlinal divisions in the examined years of cambial activity and the calculation of the relative increase of the cambial circumference. The results are discussed on the basis of the recent hypothesis of intrusive growth of fusiform initial, occurring between the tangential walls of its neighbouring initial and its closest derivative.

Highlights

Secondary xylem is one of the most valuable natural resources and numerous observations concerning the development of wood have been described recently, but still they explain mostly the molecular mechanism of wood formation, usually not taking into consideration the cambium, that is, the tissue which is the origin of each layer of wood
The formation of storeys is frequently described as the result of radial longitudinal divisions (RLD) (Cumbie, 1984; Ajmal et al 1986; Carlquist, 1988), which means that storeys are derived by successive RLDs from a single procambial cell
This species was chosen due the rapid formation of the storeyed pattern of cambial initials, which often occurs in the first few years of cambial activity

Summary

Introduction

Secondary xylem (wood) is one of the most valuable natural resources and numerous observations concerning the development of wood have been described recently, but still they explain mostly the molecular mechanism of wood formation, usually not taking into consideration the cambium, that is, the tissue which is the origin of each layer of wood. The formation of storeys is frequently described as the result of radial longitudinal divisions (RLD) (Cumbie , 1984; Ajmal et al 1986; Carlquist , 1988), which means that storeys are derived by successive RLDs from a single procambial cell (homogenous storeys). The first observations of intrusive growth of fusiform initials in the storeyed cambium led to the conclusion that the storeyed pattern is maintained despite this phenomenon (Zagórska - Marek , 1984). Examination of a climbing plant (Wisteria floribunda) revealed the heterogeneous nature of storeys, as a result of coordinated intrusive growth of the whole packets of fusiform initials (K o j s et al 2004). This research will compare the storeyed cambium formation of shrub-like species with their observations

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