Résumé:
The study realized at the Laboratory of Development and Valorization of Plant Genetic Resources, is conducted on species of Angiosperm families. This study aims to describe some examples of selected plants in relation to their economic interest. It is particularly related to the study of floral morphology and its main variations especially the description of the floral pieces and the characteristics of the pollen grains as well as the estimation of their viability. After collecting flowers of economic interest species, we proceeded to their study. The observations focused on morphology with the eyes first then with binocular on the reproductive organs and particularly on the pollen grains. The results obtained give a great variability as well in the organization of the flower from the point of view of number, color of pieces, number, shape and ornamentation of pollen grains as their viability evaluated by Alexander's coloration and in vitro germination. In fact, the number of floral pieces makes it possible to distinguish 3 categories of plants: Trimers species: Poaceae (Triticum durum Desf.), tetramers species : Oleaceae (Olea europea L.) and pentamers species: Rosaceae (Prunus armeniaca L.). The color of the flowers that can spread from white (Prunus cerasus L.) to red (Punica granatum L.) while passing from one species to another; The number of stamens by flower varies from 1 to infinite. It is often characteristic of the family or genus. When it is less than 10; They are most often free (Rosaceae). They can be welded by their anthers: Composeae and Cucurbitaceae ( Cucurbita pepo L.). The presence of fuzz helps protect the eproductive organs (stamens and pistils) species that bloom at low temperatures. The microscopic observation of the pollen grains gives off the oval shape (Fabaceae), round: Poaceae (Triticum aestivum L.) and triangular: Rosaceae. Pollen grains can be tricolor with an exine psilate (Rosaceae); round in shape, with exine psilate (Poaceae); oval in shape, with exine chinate (Asteraceae) and for the Lamiaceae family: the pollen grains have an oval shape, they are zonacolpe, with exine psilate. The mode of dispersion determines the number of pollen grains produced.
• Anemophilous species produce a considerable number of pollen grains to increase their chances of breeding (Phoenix dactylifera L., Cucumis sativum L., Vicia faba L., Pisum sativum L.). These are small and smooth. • Species that use insects to transport pollen (entomophilous species) produce fewer pollen grains that are sticky, larger and with thorns: species of the family Asteraceae (eg: Cynara scolymus L.) Finally, our results showed that Alexander staining is not the most reliable method for estimating pollen viability. With regard to in vitro germination it was possible to obtain a reliable estimate of the ability to germinate. Germination rates observed after one month of pollen conservation ranged from 7% to 33%.
