Wall protuberance formation and function in secreting salt glands of Tamarix aphylla L.

Salt glands of Tamarix aphylla consist of three pairs of secretory cells arranged one upon the other. At the stage of secretion, the upper and middle pair of secretory cells develop in their walls an internal system of anastomosed rods, the protuberances. In the formation of the wall protuberances, Golgi vesicles and microtubules appear to participate. The stage of salt secretion is also characterized by the presence of numerous mitochondria and microvacuoles. Microvacuoles contain the secreted solution and accumulate in the region of the wall protuberances. The interaction between microvacuoles and wall protuberances as well as the genesis of wall protuberances constitute new findings on the subject

Glandular and non-glandular hairs in the seasonally dimorphic Origanum dictamnus L. (Lamiaceae) as a means of adaptation to cold stress

Origanum dictamnus is a seasonally dimorphic plant having different appearance in winter and summer. Shoots of winter plants are leaf-naked except for their apical region which bears a cluster of small leaves covered with a thick indumentum of non-glandular hairs. This indumentum highly contributes to the avoidance of cold penetration into the leaf mesophyll, allowing thus plants to endure winter low temperatures. Shoots of summer plants are vigorous with large green leaves. Non-glandular hairs are dendroid with a 5-celled vertical stub and several lateral branches. Glandular hairs are of two types, large peltate hairs and small capitate hairs. Peltate hairs are numerous and consist of a 12-celled head, a unicellular stalk, and a basal epidermal cell.. They constitute the sites of essential oil secretion. Capitate hairs occur in a small number and are composed of a unicellular head, a unicellular stalk and a basal epidermal cell. They are not secreting essential oil, but a hydrophilic material. The oil secreted by the peltate hairs has antioxidant properties, opposes the oxidative stress resulted from low temperatures, and contributes to the adaptation of the plant to winter cold stress

Glandular trichomes on the leaves of Rosmarinus officinalis: Morphology, stereology and histochemistry

Stereological and histochernical analyses of the glandular trichomes on leaves of Rosmarinus officinalis were carried out using light and fluorescence microscopy. Non-glandular and two types of glandular trichomes - peltate and capitate - are described. The stereological method was used for estimating the volume density of epidermis, mesophyll, mechanical tissue, central cylinder, intercellular spaces and volume density of different types of glandular trichomes. The results showed that the volume density of adaxial epidermis was higher than abaxial epidermis. The volume density of peltate trichomes was higher than the volume density of capitate ones. The values obtained for number of peltate and capitate trichomes showed that the capitate trichomes type I were more numerous. The histochernical tests showed positive reactions to proteins and polysaccharides for both types of trichomes, while the phenolic substances were found only in peltate trichomes

Morphology of secretory structures and essential oil composition in Mentha cervina L. from Portugal

ABSTRACT: Mentha cervina L. is an aromatic plant that is traditionally used in the Alentejo region of Portugal to flavour food dishes and for the medicinal properties of the essential oil produced in its glandular trichomes. The morphology and distribution of the secretory structures of 20 populations was studied by light and scanning electron microscopy and revealed a great similarity in the type and distribution of glandular and non-glandular trichomes. In addition, two populations were surveyed at different stages of their life cycles. This showed that both maximum trichome density and maximum filling capacity of the glandular trichomes are attained early on. The GC and GC–MS chemical analyses showed that pulegone (62–80%), isomenthone (3–18%) and limonene (3–7%) are the main components of M. cervina essential oils. Cluster analysis of the identified essential oil components revealed a major chemical consistency between the 20 populations evaluate

Idioblastic mucilage cells in Teucrium polium leaf. Anatomy and histochemistry

In the mesophyll of Teucrium polium L. leaves, isolated or grouped idioblastic secretory cells occur in contact with the distal (adaxial) vessel elements of the vascular bundles. They appear to originate from one or more bundle sheath cells and their intracellular space is entirely occupied by the secretory material. The latter has a glycoproteinaceous constitution (mucilage), as histochemical tests showed. Idioblastic cells, therefore, correspond to typical mucilage cells. Mucilage seems to play a crucial role in the adaptation of the plant to unfavourable environmental conditions

The annual biological cycles of Teucrium polium L. and Thymus sibthorpii Bentham (Lamiaceae)

Teucrium polium appears in winter as a cluster of short shoots with small leaves (chamaephyte). In early spring, shoots progressively elongate until in late spring shoot elongation ceases. At the tip of each shoot, an inflorescence (dichasium with apical racemes) is developed which completes pollination by the end of July. Summer leaves are about 10-fold larger than winter leaves. In November, summer leaves are shed and the leaf-naked shoots later become dried and abscise. In winter, the dormant buds at the base of the plant break dormancy and generate many short shoots forming a claster. Thymus sibthorpii is also chamaephyte. In early spring, the short winter shoots start increasing in length and by the end of April shoot elongation becomes completed. On the tip of each shoot an inflorescence (raceme) is developed which completes pollination by the end of May. In summer, plants consist of leaf-bearing shoots only (inflorescence axes dry and then drop down). In November, all leaves are shed and small shoots sprout out from dormant buds at the base of the plant