Ontogenèse des canaux sécréteurs d'origine primaire dans la jeune plante de Pinus pinaster

Abstract

An ontogenic study of the primary resin ducts was carried out from the embryo to the 2-month-old seedlings stage in Pinus pinaster Ait. and revealed two separate systems, the hypocotyl-radicular ducts and the epicotylar ducts. In the first system, each one of the resin ducts, which are numerically equal to the protoxylem strands of the radicle, is formed by vertical juxtaposition of two canals initiated partly in the hypocotyl and in the radicle. This system is closed at the level of the cotyledonary node. The second system consists of the anastomosis of the resin ducts initiated in the base of euphylls. This system is closed at the level of the base of the epicotyl and is not correlated with the first one. The primary resin ducts are formed on a schizolysigenous pattern. In the epicotylar bud, the schizogenous and lysigenous processes are described and they occur over a long distance. This schizolysigenous process of primary resin ducts is compared in young and adult plants. Key words: resin duct, ontogenesis, schizogeny, lysigeny, seedling, Pinus pinaster.