In: Biology
10. Describe the following trends in flower evolution: petal pigmentation, organ fusion, bilateral symmetry, inflorescences.
During the diversification of flowering plants, evolutionary transitions have been observed in flowers with radial and billateral symmetry. Billateral symmetry is found commonly is species rich lineages. As for example, Lamiales and Fabaceae. Also, the symmetry in these lineages are highly elaborate. Flowering plant lineages demonstrate that evolutionary and subtle forms of billateral symmetry have evolved from radial symmetry; while the reversal is not very uncommon as well.So, this does not mean that every time a radial flower is to be considered less derived than a billateral flower.
Flowers have fewer parts that are definite in number.
The number of whorls have decreased, the floral axis has shortened,
spiral arrangement of parts is no longer, and the parts are fused.
Ovary is inferior, perianth is differentiated into calyx and
corolla. Radial symmetry of early flowers given way to bilateral
symmetry.