Beiträge zum anomalen sekundären Dickenwachstum im Sproß einiger annueller Atriplex- und Chenopodium-Arten

Abstract

Serial sections of seedling stems and of young and old woody stems of Atriplex nitens S chkuhr , Atriplex patula L., Atriplex prostrata B oucher ex DC., Atriplex tatarica L., Chenopodium glaucum L., Chenopodium hybridum L. and Chenopodium rubrum L. were studied with the light microscope as to the mechanism of anomalous secondary thickening and development of the thickening during the annual life cycle. The first additional cambium develops outside the primary vascular bundles in the inner layer of cortex. The initiation of the secondary thickening deviates from that typical of most dicotyledons – a circle of interfascicular and fascicular cambium is not formed. The first additional cambium (a residuum cambium) produces the xylem groups inwards, outwards the phloem groups. But not all cells differentiate to phloem, the outermost layer remains active and forms the secondary additional cambium. That means that the additional cambium is always initiated in continuation with the previously formed cambium. During the annual life cycle, 12–17 cambia are formed in the hypocotyl of Atriplex species and 5–7 cambia in the hypocotyl of Chenopodium species.