Glandular trichomes of Calceolaria adscendens Lidl. (Scrophulariaceae): histochemistry, development and ultrastructure

This paper reports the results of a study of the morphology and development of glandular trichomes in leaves ofCalceolaria adscendensLidl. using light and electron microscopy. Secretory trichomes started as outgrowths of epidermal cells; subsequent divisions gave rise to trichomes made up of a basal epidermal cell, a stalk cell and a two-celled secretory head. Ultrastructural characteristics of trichome cells were typical of terpene-producing structures. Previous phytochemical studies had revealed thatC. adscendensproduces diterpenes. Comparison withC. volckmanni,which produces triterpenes, and has trichomes with eight-celled secretory heads, suggests that there could be a relationship between the type of glandular trichome and the class of terpene produced. Further work is needed to test the hypothesis and to develop trichome characters as taxonomic tools