REVIEW Seasonal development of secondary xylem and phloem in Schizolobium parahyba (Vell.) Blake (Leguminosae: Caesalpinioideae) Carmen Regina Marcati Æ Camilla Rozindo Dias Milanez Æ Silvia Rodrigues Machado Received: 30 April 2007 / Revised: 30 August 2007 / Accepted: 6 September 2007 / Published online: 10 October 2007 Ó Springer-Verlag 2007 Abstract The cambial activity and periodicity of sec- ondary 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 phe- nology 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. Keywords Cambial activity Á Marginal parenchyma Á Schizolobium parahyba Á Secondary phloem Á Secondary xylem Introduction Studies on the cambial activity, mainly of xylem formation, provide not only data about the age of trees but also clues about the possible factors that control tree growth. This type of data is also helpful in dendrochronology, in pre- dicting timber and biomass yield, and in determining forest dynamics (Jacoby 1989; Kozlowski et al. 1991; Eckstein et al. 1995; Priya and Bhat 1999). Studies about the seasonal formation of secondary xylem and phloem in tropical trees have involved mainly Indian species (Ghouse and Hashmi 1979, 1980a, b; Dave and Rao 1982; Deshpande and Rajendrababu 1985; Ajmal and Iqbal 1987; Iqbal and Ghouse 1987; Venugopal and Krishnamurthy 1987; Rajput and Rao 1998; Rao and Rajput 1999, 2000, 2001; Rajput and Rao 2001; Venug- opal and Liangkuwang 2007), but are relatively scarce for Brazilian species. Marcati et al. (2006) studied the cambial activity and annual rhythm of xylem production of Ced- rela fissilis (Meliaceae) from the standpoint of phenology and climatic factors. Studies about the seasonal formation of secondary xylem and phloem of several other species have yet to be published (Luchi, Amano, Marcati and Angyalossy). Schizolobium parahyba (Vell.) Blake (Leguminosae: Caesalpinioideae), popularly known as guapuruvu, is a deciduous legume species originating from Brazil’s southern and southeastern regions. It is one of the fastest growing tree species, which is why it is used extensively in reforestation projects using native trees (Carvalho Communicated by R. Aloni. C. R. Marcati (&) Departamento de Recursos Naturais, Cie ˆncias Florestais, Sa ˜o Paulo State University, SP, CP 237, CEP, Botucatu 18603-970, Brazil e-mail: carmen@fca.unesp.br C. R. D. Milanez Á S. R. Machado Departamento de Bota ˆnica, Instituto de Biocie ˆncias, Sa ˜o Paulo State University, SP, CP 510, CEP, Botucatu 18618-000, Brazil e-mail: smachado@ibb.unesp.br 123 Trees (2008) 22:3–12 DOI 10.1007/s00468-007-0173-8