The Morphology of the Inflorescence in Ranunculus bulbosus L.

This paper records the form variation of 750 inflorescences of Ranunculus bulbosus L. collected randomly from each of two large colonies growing on permanent grassland. Each inflorescence has a terminal flower, 1–4 bracts on the main axis and up to 8 flowers borne on cymes subtended by these bracts. Over 75 per cent, of each sample consists of inflorecences with 2 or 3 bracts on the main axis and 2–4 flowers. The number of flowers increases with the number of bracts on the main axis and evidence is given that the 4-bract 9-flowered inflorescence may be nearly the largest and most complex that can be produced under these conditions. The distribution of flowers in the axillary cymes is such that the inflorescences tend to be radially symmetrical and pyramidal in form. This is so even thought with increase in the number of bracts on the main axis the proportion of axillary flowers decreases in the lowest cyme and increases in the cyme above. It is considered that the form and size of the inflorescence can be related to the vigour of the plant and to the mechanical and nutritional problems involved. A comparison of the various types of inflorescences found probably reflects the developmental sequence of flower production. It also indicates that there is competition between certain potential flower positions as the inflorescence develops.