Steps Toward a Natural System of the Dicotyledons

Embryological character states are mapped on the diagrams of dicotyledons (G. Dahlgren 1989). The often well-defined pattern of distribution forms a basis for discussing and clarifying phylogenetic relations. It is shown how numerous embryological characters, alone or in combinations, support certain systematic constellations, even if the character states may have arisen independently within a varying number of evolutionary lines. Characters presented are: anther wall formation; tapetum types; cells in pollen grains at dispersal; microsporogenesis; ovule morphology; ovule integuments; endothelium; obturator; parietal tissue; embryo sac formation; antipodal cells; hypostase, embryogeny; polyembryony; endosperm formation; persistence of endosperm; ruminate endosperm; endosperm haustoria; perisperm; storage compounds in the endosperm; chlorophyllous embryo; embryo size, seed coat characters; arils; dry and wet stigma types.