Der multilakunäre Knoten einiger Melianthus- und Greyia-Arten im Vergleich mit anderen Knotentypen

Abstract

Summary Three species of Melianthus as well as two species of Greyia have multilacunary nodes. The petiolar base of Melianthus comosus and M. minor is vascularized by five leaf traces out of five lacunes, the stipules being supplied by branches departing from the lateral leaf traces. In Melianthus major petioles are vascularized by ten traces; on one side the median stipule is vascularized by both the whole outermost (fifth) lacunary trace together with branches of other lacunary bundles and, on the other side, by branches originating from lateral lacunary traces only. There are nine lacunes in Greyia sutherlandii and G. radlkoferi (which both lack stipules, their petiolar bases being sheathing). Ventral bundles running lengthwise within the petioles of these Melianthus species are derivatives not only from the median lacunary trace, but they are mainly derived from the traces next to them The unilacunary nodes of Bignoniaceae are, unlike the unilacunary one-trace nodes of Jasminum species, considered as a “multi-trace” resp. a “complex” type. The unilacunary nodal type is discussed as probably evolved from the multilacunary condition.