Ricerche Embriologiche Sulla Famiglia delle Rhamnaceae

Summary

In this research we describe the embryology relating to the ovule from the first stages of the archesporium to the grown up gametophyte in Rhamnus Alaternus L., Colletia cruciata Gill. et Hook., Colletia spinosa Lam. Paliurus aculeatus Lam. and Hovenia dulcis Thunb. We ascertain everywhere a very analogous behaviour in the formation of the gametophyte, which is of the Normal type, except a very few irregularities, while the condition of the archesporium is various in the different species. We describe also the microsporogenesis observed in three species. We establish the aploid numbers 12 for Paliurus aculeatus, 11 for Colletia spinosa and the diploid number 22 for Colletia cruciata. We describe at last a remarkable parthenocarpic capacity in Colletia spinosa and the sterility probably due to a scanty vital mutation in an individuum of Paliurus aculeatus.