The Ultrastructure of the Glandular Trichomes of Solanum tuberosum

The potato plant has two types of glandular trichomes whichwere investigated by electron microscopy. One type has a eight celled globular head on a neck cell anda stalk cell Each glandular cell has many rather large vacuoles,a large nucleus, many ribosomes and mitochondria, a few Golgibodies, and darkly coloured, often irregular plastids (chloroplasts).The plastids are mostly located near the axial cell wall borderinga large central intercellular space filled with secretion materialThe plastids are assumed to participate in the formation ofthe secretion material, which reacts positively to esterasetests. The outer wall is covered by a thin cuticle. The other type has a club-shaped multicellular head on a singlestalk cell. The cytoplasmic features in the cells are similarto those of the globular-headed trichome, except that they possesslarge central vacuoles and randomly distributed plastids. Centricendoplasmic reticulum has been observed in young cells. Intercellularspaces develop between the cells and into the outer wall, whichis thus split into two. Whereas the older glandular cells reactpositively to tests for esterase, the secretion material itselfis pectinaceous and reacts negatively. The outer wall is cutinizedand covered by a cuticle. Solanum tuberosum L., potato, glandular trichomes, ultrastructure     

Studies on Mature Seeds of Cuscuta pedicellata and C. campestris by Electron Microscopy

The seeds of Cuscuta pedicellata have been investigated by transmissionand scanning electron microscopy. Additional observations havebeen made on seeds of C. campestris by SEM only. The seed coatconsists of an outer single epidermis, two different palisadelayers, and an inner multiparenchyma layer. The outer epidermalwall in C. pedicellata has a thick cuticle and zones rich inpectic substances. The thicker ‘U-shaped’ cell wallsin the outer palisade layer are strengthened by a wall layerof hemicellulose. The inner palisade layer has thick walledcells with a ‘light line’. The inner cell wall ofthe compressed multiparenchyma layer has a thin cuticle. A fairlythick cuticle is positioned directly on the endosperm surface.The aleurone cell walls are different from the remaining endospermwalls. The latter are thick and believed to be of galactomannans.There is a ‘clear’ zone between the plasmalemmaand the cell wall in the aleurone cells. The embryo cells arepacked with lipids and proteins. In Cuscuta campestris mostendosperm has been absorbed during the seed development. Theembryo apex has two minute leaf primordia. The features of theCuscuta seeds are discussed in relation to functional and environmentalconditions. Cuscuta pedicellata, Cuscuta campestris, seed, seed coat, cuticle, cell walls, endosperm, aleurone cells, galactomannan, embryo, TEM, SEM     

Functional leaf anatomy of Bomarea Mirb. (Alstroemeriaceae)

The leaf anatomy of Bomarea is described and related to ecological conditions. The principal architecture of all species is very similar; adaptations are developed in numerous differences, for instance degree of lignification. All species have inverse leaves, the adaxial side being the stomatous side. In most species, the leaves are resupinate, the lower surface being the adaxial. Theories for the cause of resupination are discussed.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 152 , 73–90.     

Comparative and functional leaf anatomy of selected Alstroemeriaceae of mainly Chilean origin

The resupinate leaves of 16 species of Alstroemeriaceae were examined using light- and scanning electron microscopy. The leaf anatomy is described for all of the species, that of the petiole and stem for selected species. The mesophyll consists of chlorenchyma and includes idioblasts that contain raphides. Dorsiventral, isolateral or isobilateral leaf types were observed. Petioles are always isolateral. Two epidermal types are commonly observed: type I contains jigsaw puzzle-like intercostal cells and longitudinally elongated cells above the veins; type II contains only longitudinally elongated cells, usually longer, above the veins. Some species have an epidermis which differs from the main types. All species show adaptation to resupination by having an inverted anatomy. Due to the twist of the leaves, adaxial indicates the lower surface and abaxial the upper. Stomata are found on both surfaces. Palisade cells, when they occur, are always on the abaxial surface. Most species are mesomorphic in spite of the dry environments in which they grow; a few show xeromorphic features. The leaves are compared and discussed with relation to ecological conditions.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 261−272.     

Xeromorphic features of three stem assimilants in relation to their ecology

The anatomy of the assimilating stems of three brooms (Fabaceae) all show distinct xeromorphic features in their tissues, but these are developed to different degrees. The epidermis consists of very thick, cutinized outer walls, deeply sunken stomata, and a dense layer of trichomes, at least in younger steins. In older sterns some of the stomata are blocked by cell-plugs. The chlorenchyma is multilayered. The main supporting tissue consists of peripheral gelatinous fibre strands. It is argued that these may function in water storage. Parenchymatous water storage cells are present in the pith of two species. The structure and function of the xeromorphic features are discussed in relation to the ecology of the plants.