Sympodial Cyme

A special type of modified cyme which superficially resembles a raceme or spike is the sympodial cyme, in which the apparent main axis consists of a succession of short axillary branches. Each flower is terminal to its true axis, but the side branch originating just beneath the flower produces its own terminal flower with another side branch just beneath it, so that theoretically
the inflorescence can elongate indefinitely by producing a branch just below each flower. Sympodial cymes are of two types, helicoid and scorpioid. In a helicoid cyme the branches are all on the same side of the developing axis, so that the inflorescence is curved or circinately rolled. Often the inflorescence is conspicuously circinate when young and progressively unrolls as flowering proceeds. In a scorpioid cyme the branches are alternately on opposite sides of the developing sympodial axis, so that the axis has a zig-zag appearance. Helicoid cymes are commoner than scorpioid cymes and are expecially frequent in the Boraginaceae and Hydrophyllaceae.

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