flowers that should be fragrant but not
I might be fun and interesting to list and compile plants whose flowers should be fragrant by virtue of appearance, name, or taxonomy.
Why do plant's give up fragrance in their flowers? Many plants have flowers with no nectar (1/3 of orchids or about 10,000 species lack nectar) Research has shown that plants with flowers that lack nectar out cross more often. This is because the pollinator moves on after sampling a flower or two without nectar, so visit more plants per foraging bout. Pollinators that stay on the bush and move flower to flower are picking up and delivering pollen from of the same plant promoting self pollination which results in a narrower gene pool.
But what could be the selective advantage of giving up fragrance. For instance all Plumaria have fragrance except P. pudica. Why was fragrance selected against in this species?
Here are some to begin with. I am thinking mainly of plants that have not been messed with by man and woman.