Seasonal development of secondary xylem and phloem in <Emphasis Type="Italic">Schizolobium parahyba</Emphasis> (Vell.) Blake (Leguminosae: Caesalpinioideae) |
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Authors: | Carmen Regina Marcati Camilla Rozindo Dias Milanez Silvia Rodrigues Machado |
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Institution: | 1.Departamento de Recursos Naturais, Ciências Florestais,S?o Paulo State University,Botucatu,Brazil;2.Departamento de Botanica, Instituto de Biociências,S?o Paulo State University,Botucatu,Brazil |
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Abstract: | The cambial activity and periodicity of secondary xylem and phloem formation have been less studied in tropical tree species
than in temperate ones. This paper describes the relationship between seasonal cambial activity, xylem and phloem development,
and phenology in Schizolobium parahyba, a fast growing semideciduous seasonal forest tree from southeastern Brazil. From 2002 to 2003, wood samples were collected
periodically and phenology and climate were recorded monthly in the same period. S. parahyba forms annual growth increments in wood, delimited by narrow initial parenchyma bands. The reduction of the cambial activity
to a minimum correlates to the dry season and leaf fall. The higher cambial activity correlates to the wet season and the
presence of mature leaves. In phloem, a larger conductive region was observed in the wet season, when the trees were in full
foliage. The secondary phloem did not exhibit any incremental zone marker; however, we found that the axial parenchyma tends
to form irregular bands. |
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Keywords: | Cambial activity Marginal parenchyma Schizolobium parahyba Secondary phloem Secondary xylem |
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