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

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 Laburnum anagyroides, 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