Author name:
امل علي ياسين الحسن
Abstract:
The study was conducted to investigate several taxonomic aspects which comprised the micro - morphological studies of epidermal layer of leaves, pollen grains, fruits and seeds.In addition to that, the anatomical and molecular studies for 12 species of Euphorbiaceae family which belonged to five genera AndrachneL. , Chrozophora L., Euphorbia L, Mercurialis L. and RicinusL., were performed. One representative species for each genuswas selected; in exception 8 species were chosen for the genus Euphorbia..The current results confirmed that the anatomical characters showed valuable taxonomic traits which can evidently be used to distinguish between species. The most prominent trait was mesophylla tissue in leaves which were observed in three categories;1 - Bifacial leaves : - which found in C.tinctoria, Euphorbia sp ., E. milii, E.annua and R.comminus 2 - Uni - facial (heterogenus) leaves : - this category of the mesophyll was detected in two species only A.telephioides and E.prostrata3 - Uni - facial (homogenus) leaves : - this category were noticed in five species; E.denticulata ,E.helioscopia ,E,macrocarpa , E.microsphaeia and E.peplus The second important comparative anatomical character was the Mid rib, which are in four types with several shapes from which discrimination between the species can be made : - 1. Convex - concave mid rib : - that was showed in E.helioscopia, E.macrocarpa, E.milii and M.annua.2. Convex - convex : - This type was found in three species C.tinctoria , Euphorbia sp.and R. comminus3. Flat - Convex : - This type of mid rib was observed in A.telephioides E.microsphaera, E.peplus and E.prostrata4. Flat - Flat : - This type was observed in only one species E.denticulata In stem, the most prominent parts of taxonomic evidence were pith and vascular bundles.In according to the pith, species can be divided into hollow stem (without pith) and solid stem (containing medulla good configuration). Hollow stem was clear in the stems of A.telephioides , E.microsphaera , E.prostrata and M.annua. While, the solid stem wasseen in the remaining species. Vascular bundles were existed in two types; that's connected vascular bundles that's characterized the hollow stems, and separate vascular bundles. In most of the species with the exception of M. annua, stem with scatteredvascular bundles were in cortex As well as, petiole which have features that a clear taxonomy values .either by outline of petiole or its vascular arc.Micro - morphological studies of epidermal layer of leaves showed very important taxonomical value. This layer of leaves reveals variation in shape of ordinary epidermal cell and nature of anticline cell wall, stomata complexes and Epicuticlular wax crystals.Micro - morphological of pollen was taxonomic evidence as well. It can be considered to divide the species of Euphorbiaceae family into two groups based on the number of germination apertures 1 - Hexocorporate : - this type was confined to C.tinctoria2 - Tricolporate all species studied remainingThe sculpture of pollen wall provided beneficial information invested in the species identification.Both seeds and fruits showed a distinctive role in species identification. Micromorophological study of seeds for species which belong to six genera Andrachne , Chrozophora, Euphorbia, Mercurialis , Phyllanthus and Ricinus were achieved by using Scanning Electron Microscope(SEM). The study concentrated on micro - morphological aspect of Caruncle, seed surface ornamentation and the shape of epidermial cell wall. The result revealed that most studied species were with carunclated seeds ,but some specieswere with ecarunclated seeds as in A.telephioides L. ,C. tinctoria( L) Raf , E.prostrata Atin and P. maderaspatensis L Seed surface ornamentation characteristics showed a significant taxonomical value.Furthermore, current result showed that there are a highly variation in shape, size and color of the seeds walls. With respect to the fruits characteristics, which showed variations in number of mercarpi, shape, size, color and surface ornamentation that can be adopted in the separation of the species studied Molecular study provided significant support for phenotypic and anatomical classification and support genetic convergence between the species in Euphorbiacea family. The genus Euphorbia species showed a significant genetically convergence and participated in predecessors monophyletic. However, the genera in Euphorbiacea family under study probably originated and evolved from different ancestors’ polyphyletic.
