Ascular Anatomy of Ranalian Flowers. I. Ranunculaceae

As the descriptions, discussions, and general conclusions have shown, all of the 17 representative species of the Ranunculaceae studied agree as to fundamental floral vascular structure. The axis is a simple one. All floral organs are usually inserted spirally (modifications occur in Aquilegia and Ranunculus). Three types of floral organs are present: carpels, stamens, sepals. The sepals are fundamentally three trace trilacunar organs. The carpels also are fundamentally three trace trilacunar organs, and in addition are multiovulate. The uniovulate single trace carpel is derived from the former. This change has been accomplished by a gradual reduction in the number of ovules from many to few to one, and a lateral fusion of the three traces to form a single strand. Stamens are unique organs in that they always receive but a single trace. Petals are evidently modifications of stamens; hence they always differ from the sepals in being definitely single trace organs. Within this unified natural primitive family, three or four distinct lines of divergence occur: (1) Caltha, Trollius, Coptis, Actaea; (2) Hepatica, Anemone, Clematis, Anemonella, Ranunculus; (3) Thalictrum; (4) Aquilegia. Evidence exists also of the suppression of organs (carpels, Caltha; ovules, Trollius). Thus the aggregate of facts makes the low phylogenetic position of the Ranunculaceae more certain. This investigation also is forming the basis for another study. This is a comparative study of the vascular anatomy of the flowers of the Ranunculaceae with that of the remaining families of the Ranales and other groups considered to radiate from the "Ranalian plexus."