XVI International Botanical Congess

Some of the mutant phenotypes described by developmental geneticists have successful counterparts in nature. The talk will cover examples from Agnes Arber's work, including her superb book The Natural Philosophy of Plant Form" (1950), as well as examples from contemporary plant morphologist: (1) Indeterminate flowers with repetitive flower production in Nymphaea prolifera resemble the agamous mutant of Arabidopsis. (2) Flat green roots and stems of river-weeds (Podostemaceae) resemble fasciation mutants, including clavatal and clavata3 of Arabidopsis. Sveral natural forms of plants probably arose as mutant phenotypes of genes homologous to those in the model organisms. Arber (1950) concluded: Macroscopic nature is never really anomalous. Abnormalities, like other exceptional cases, at least show incontestably, what the plant CAN do". One thing they can do is transcend the orthodox distinction of root and stem and leaf, as implicated by Arber's partial-shoot theory" in vascular plants.