Homeotic mutants have been useful for the study of animal development. Such mutants are also known in plants. The isolation and molecular analysis of several homeotic genes in Antirrhinum majus provide insights into the underlying molecular regulatory mechanisms of flower development. A model is presented of how the characteristic sequential pattern of developing organs, comprising the flower, ...

Flowering plants in Australia have been geographically isolated for more than 34 million years. In the Northern Hemisphere, previous work has revealed a close fit between the optimal discrimination capabilities of hymenopteran pollinators and the flower colours that have most frequently evolved. We collected spectral data from 111 Australian native flowers and tested signal appearance consideri...

The completion of flower development in Impatiens balsamina requires continuous inductive (short-day) conditions. We have previously shown that a leaf-derived signal has a role in floral maintenance. The research described here analyzes the role of the leaf in flower development. Leaf removal treatments, in which plants were restricted to a specified number of leaves, resulted in flowers with i...

Flowering is controlled by a variety of interrelated mechanisms. In many plants, the environment controls the production of a floral stimulus, which moves from the leaves to the shoot apex. Apices can become committed to the continuous production of flowers after the receipt of sufficient amounts of floral stimulus. However, in some plants, the commitment to continued flower production is evide...

Antirrhinum majus, Flavonoid Biosynthesis, Flavanone Oxidase, Apigenin, Luteolin Enzyme preparations from flowers of Antirrhinum majus catalysed the oxidation of naringenin to apigenin and of eriodictyol to luteolin. Enzyme activity was found to be localized in the microsomal fraction. The reaction required NADPH as cofactor and had a pH optimum of about 7.0. The NADPH-dependent microsomal enzy...

In self-compatible, hermaphroditic plants, display size-the number of flowers open on a plant at one time-is believed to be influenced by trade-offs between increasing geitonogamous selfing and decreasing per-flower pollen export as display size increases. Experimental results presented here indicate that selection through male function favors smaller display sizes in Ipomoea purpurea. In small...

Microscopic observation of bi-weekly sampled terminal buds revealed that most flower buds of R. mucronatum were formed between late-July and mid-August and differentiation of specific floral organs was completed before mid-October. Flower buds continued to enlarge through the winter. When flower buds on two-yearold plants from rooted cuttings were allowed to grow at day / night temperature of 1...

DEVELOPMENTAL FATE DECISIONS IN CELL POPULATIONS FUNDAMENTALLY DEPEND ON AT LEAST TWO PARAMETERS: a signal that is perceived by the cell and the intrinsic ability of the cell to respond to the signal. The same regulatory logic holds for phase transitions in the life cycle of an organism, for example the switch to reproductive development in flowering plants. Here we have tested the response of ...