Fig. 5

Tordylium apulum. Morphogenesis of the umbel (A–E) and ray flowers (F–H). A FUM fractionates the first umbellet meristem. B Subsequent umbellet meristems are initiated in a spiral pattern. Note the tiny primordium of the involucral bract. C Umbellets begin to elongate stalks (raylets) which results in their physical separation. D Ray flower meristems begin to fractionate floral organs. E Radial flower meristems fractionate floral organs when ray flowers start gynoecium formation F First floral organs are initiated from the naked, spherical ray flower meristem in a group-like patterns. G Ray flower meristem before gynoecium initiation. Note enlarged abaxial sepals (sp 1 and sp 3). H Ray flower bud showing enlarged abaxial petal lobes (Orlaya-type zygomorphy). For colours and abbreviations, see Fig. 2. Scale bars = 100 µm