ISHS Acta Horticulturae 614: VI International Symposium on Protected Cultivation in Mild Winter Climate: Product and Process Innovation
PLANT GROWTH AND DEVELOPMENTAL CHARACTERISTICS OF DANAE RACEMOSA |
| Authors: | C. Cervelli, E. Scordo, P.G. Fadelli, A. Tallone, S. Castello |
| Keywords: | Ruscus racemosus, bud development, plant growth, rhizome, phylloclades |
| Abstract:
A tree-year activity was carried out on Danae racemosa (Ruscus racemosus) to characterize the development of rhizome buds and their internal structures. Photographic material was obtained and microscopic observations were carried out every 60-80 days in the course of the year. The growth of different plant organs (stems, rhizome, roots, fruits) was also measured. The morphological organization of Danae rhizome is based on the development of two new sympodial units for each previous one, with buds originated from branching of the main axis arranged in two opposite ranks on a sole vertical plane. Every year one sympodial unit develops and an aerial stem with phylloclades elongates; till four erect buds are inserted at the base of the aerial stem: the two proximal ones represent two new sympodial units and begin every winter a new branching cycle; one or two distal buds develop only phylloclades inside, but usually do not produce stems because die in summer without elongating. Phylloclade differentiation starts between May and July. As each new sympodial unit grow orizontally right-angled with the previous one, the rhizome proceed by a zigzag growth, with a theoretical 2n increase (n = no. of years) of growing points for each year. The accumulation of dry weight by aerial part of the plant (foliage) is restricted to spring (stem elongation and hardening), but both rhizome and roots have a more or less continuous growth, with a higher dry weight increase in the warm period of the year. Each organ increases its weight twice or more each year. Roots represent about 50% of dry weight of the plant. | |
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