A review of the genus Nymphoides (Menyanthaceae) in Iran

The genus Nymphoides is a freshwater aquatic dicot represented by two species in Iran. Based on our current regional taxonomic revision of this genus, we recognize Nymphoides cristata, previously identified as Nymphoides indica in Flora Iranica. However, these species are easily distinguished from each other by having crested petal lobes in the latter. We investigated the morphology and anatomy of Nymphoides cristata and Nymphoides peltata. The most important morphological features for differentiation between these species are corolla color and inflorescence type. The anatomy of cross-sections of leaf, petiole, stem and the surface sections of leaf were studied. The following characters were found to be taxonomically informative: the presence of stellate, polyramous and ramiform foliar sclereids as well as the presence of astrosclereids in petioles and stems of both examined taxa, while spheroidal sclereids are only observed in the stems of Nymphoides peltata.

Foliar sclereids in tea and its wild allies, with reference to their taxonomy

Camellia sinensis (L.) O.Kuntze and most of its wild allies are used for tea throughout China and in many other parts of the world. Although they all belong to Camellia section Thea, their infrasectional classification remains controversial, resulting from heavy reliance on macromorphological features. Furthermore, the identification of tea from the fragments of processed leaves is quite difficult because of the lack of reliable characters. Here, foliar sclereids of 28 species and five varieties were investigated and used to explore their utility in addressing taxonomic problems and identification of commercial teas. Our data showed that foliar sclereids exhibit a wide diversity in this section. They could be divided into 12 types (including a newly recorded dendritic type) and two distribution patterns in the leaf blade. Their forms, type combinations and distribution patterns are reliable features, not particularly influenced by environmental factors, although their distribution density sometimes varies. In addition, they appear constant in individuals of different ages within the same wild population. We conclude that foliar sclereids in the section Thea are relatively stable and their diversity and regularity are of some taxonomic value.

FOLIAR SCLEREIDS IN DIONYSIA (PRIMULACEAE) FROM A PHYLOGENETIC PERSPECTIVE

Sclereid presence and distribution were studied in leaves from 50 species of Dionysia (Primulaceae). Of 16 species not previously investigated, 11 were shown to possess sclereids. The sclereids are dermal, terminal or diffused (according to the position in the leaf) and develop from different tissues, and hence are not homologous structures. The presence of different types of sclereids in different species is discussed. Sclereid characters are optimized on a cladogram based on an analysis of three DNA regions. Some clades are associated with certain types of sclereids. Terminal sclereids are most common in Iran, and diffused sclereids in Afghanistan. The evolution of sclereids in the genus is discussed, and a redefinition of what can be called a sclereid in Dionysia is presented.

Anatomical studies in West Malaysian Icacinaceae

On the basis of a comparative anatomical study of the leaf lamina and petiole of six genera of Icacinaceae in West Malaysia, these genera can be classified into four closely knit groups by virtue of their many shared characters: Group I comprises Cantleya, Gomphandra and Stemonurus whereas Groups II and III are made up of Gonocaryum and Sarcostigma, respectively. The climber genus Iodes is classified into Group IV. Taxonomically useful characters include the shape of the vascular bundles in both the midrib and petiole, the presence of funnel-shaped palisade cells, foliar sclereids, tannin crystals, hypodermis layer and accessory or wing bundles in the petiole. A key to the genera and the descriptions of each species and variety based on anatomy are given. Phylogenetic relationship among the genera are also discussed based on the study with data supplemented from other taxonomic sources.

Foliar sclereids of Olea europaea may function as optical fibres

Adaxial epidermises that contained an intact "subepidermal" "T"-shaped sclereid network, were isolated from olive tree leaves using a new method of enzymatic maceration. In the leaf, the sclereid network was anchored on the adaxial epidermis. The basal parts of the T-shaped sclereids penetrate the palisade cell layers into the underlying spongy parenchyma cells. In paradermal sections, the basal parts of the sclereids appeared as light-emitting sources or spots among the dark-green background of the palisade layers. The light spots almost disappeared when the intercellular air spaces were filled with immersion oil that had a similar refractive index to that of cell walls. It is plausible that light is propagated through multiple reflections between the thick cell wall of sclereids and the air filling the intercellular spaces, the former having a significantly higher refractive index. Sclereids act like synthetic optical fibres and, besides other functions, they may contribute to the improvement of the light microenvironment within the mesophyll of the thick and compact sclerophyllous leaves of Olea. Key words: foliar sclereids, optical fibres, light guiding, Olea europaea.