Glandular Trichomes of the Sweet Chestnut

The glandular trichomes of the sweet chestnut (Castanea sativa) have been studied with SEM, TEM and light microscope techniques. Three types of trichomes are present on the leaf epidermis and on young stems. Two types, the stalk and head, are well-defined, while a third type, the head, is not clearly defined. The cells of both the head and the stalk arise by successive anticlinal and periclinal divisions from a protoepidermal cell. Higher gland density was found on the upper surface than on the lower surface. Density also depended on leaf development stage and growth conditions; it is highest at early stages of development, while no trichomes were present on senescent leaves. Leaves grown in vitro showed higher gland densities than those from free-growing trees. In both stalk and head cells, a single large vacuole with a sinuous tonoplast occupies the greater part of the cell body, the cytoplasm forming an irregular fringe around the outside. Dissolved and suspended tannins are present in high quantities. Organelles are almost entirely lacking in the cytoplasm, although plasmodesmata ("presumably" implicated in the grandular function of the trichome) occur at high density. Glandular products accumulate in a cavity between the trichome head and an overarching cuticle in which no pores of any type are visible.

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Author(s): Ma Luisa Vieitez

Publication: American Chestnut Proceedings - 1992