Macro- and micro-morphometrical seed characters in seven species of Egyptian Datura and Nicotiana (Solanaceae)

This work describes and compares the external macro- and micro-morphometrical features of the seed of seven species of Datura and Nicotiana belonging to two tribes of the Solanaceae. Fourteen unique characters were measured and described, the results of which reveal marked differences, both among and within genera. The species of Datura exhibited higher values than those of Nicotiana in all morphometrically measured parameters, such as seed weight, size, perimeter, and surface area, with no or little variation in roundness and eccentricity. For qualitative features, the notched outline, rough texture, pitted ornamentation, circular hilum shape, and stellate coat pattern characterized all examined species of Nicotiana. The yellow colour of the seeds can be used to distinguish the seeds of Nicotiana glauca from the brown seeds of other Nicotiana species examined in this study. The circular shape of the hilum distinguishes the seeds of Datura innoxia from those of Datura metel, which have oral-shaped hilum. Considerable differences in seed coat morphology were found both among and within species. However, the size and shape of the seed can be useful and stable characters, and the position of the hilum had some taxonomic significance.

Evaluation of morphological and anatomical characters for discrimination and verification of some Medicago sativa (L.) Cultivars

<italic>Medicago sativa</italic> L. (alfalfa) is one of the most important legume forages in the world. The objective of this study was to characterize and discriminate among 15 alfalfa cultivars with a different geographical origin. Macro-morphological and anatomical characters as well as seed coat sculpture were investigated. Twenty five morphological characters were extracted directly from the fresh specimens. Transverse section in the main stem were carried out; stained and seventeen anatomical characters were examined by light microscope. Seed coat surface was investigated using Scanning Electron Microscope (SEM). Data obtained were coded and analysed using NTsys-Pc software (Version 2.02) and the resulted dendrogram is discussed. The results showed morphological and anatomical variation between the studied taxa. Vascular bundles ranged from 16 to 23. The Egyptian cultivar Nubaria has the lowest number of vessels (16) while the American Super supreme has the larger number (23). The seed coat ornamentation revealed five main surface patterns and suggests the presence of variations in anticlinal boundaries and periclinal walls that provide stable diagnostic characters for morphologically closely related taxa. The dendrogram showed that the Egyptian cultivar Nubaria was the most distant and clustered separately from all the other alfalfa cultivars which were grouped into two main clusters. Seed coat morphology and combination of other plant morphological and anatomical characters permitted identification and discrimination between the examined cultivars. Results obtained in this work could be considered for further breeding strategies and studies.

Phylogenetic position and taxonomic assignment of Thlaspi aghricum P.H.Davis & K.Tan (Brassicaceae)

A general review of the taxonomic status of Thlaspi past and present is given, and a critical evaluations of its segregates based on both morphological and molecular data are presented. ITS molecular phylogenetic study of Thlaspi aghricum and related species, as well as seed-coat morphology and anatomy strongly support the placement of the species in Noccaea. The new combination N. aghrica is proposed, and detailed description and distribution of the species are given.

Description of some characteristics of flowers and seeds of Arabidopsis thaliana - ecotype landsberg erecta and mutant NW4

Flowers and seeds of Landsberg <em>erecta</em> (Ler) ecotype and NW4 mutant were studied by light microscopy and scanning electron microscopy to reveal characteristic features of their structure. The NW4 mutant flowers differ from Ler mainly in presence of two bract-like sepals with complicated vasculature and a variable number of secondary flowers. In the two outer whorls of NW4 flower, variable number of transformed stamen-, petal-, sepal- and style-like elements also occur. The NW4 mutant seeds are characterized by the absence of mucilage around the surface and a deviating seed coat morphology.

SYSTEMATIC AND ECOLOGICAL SIGNIFICANCE OF SEED COAT MORPHOLOGY IN SOUTH AFRICAN CAMPANULACEAE SENSU STRICTO

The seed coat morphology of 50 species of Campanulaceae sensu stricto, representing all 10 South African genera, was studied by scanning electron microscopy to gauge its usefulness in the diagnosis of genera or to support clades. Possible correlations with life form (annual, herbaceous and woody perennial) and ecological requirements such as fire response, rainfall requirements, bedrock and soil preferences, as well as habitat (e.g. fynbos, strandveld, renosterveld, grassland and karoo), were also investigated. Patterns of variation are described and interpreted as conforming to two seed coat types: reticulate (Type 1) and striate/wavy (Type 2). Type 1 seeds are further divided into eight subtypes. Some general trends emerged; for example, Type 1 seeds occur in all major clades of wahlenbergioids, Type 1A with a smooth coarsely reticulate surface being predominant in fynbos taxa, all of which are woody perennials. Several of the Type 1 seeds, together with Type 2 seeds, also occur in species with wider ecological amplitude, for example in karoo, strandveld or montane grasslands. In Siphocodon there is remarkable disparity in seed type between species. These variations in seed type generally appear to accord with current knowledge of climatic changes and soil evolution during the Tertiary of South Africa, and may be useful indicators of generic emergence and mosaic speciation in the major lineages of wahlenbergioids. However, it was concluded that seed coat types do not correlate closely enough with specific ecological requirements or life forms to be of unequivocal predictive value. Also, apart from Merciera and Treichelia, they are of limited use as a diagnostic character for genera, but are useful for distinguishing species.