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We now know what the 'first flower' looked like – but when did it bloom? | Susannah Lydon

24 / 08 / 2017, The Guardian

The fossil record for flowering plants has been a hot topic since Darwin’s day and despite recent breakthroughs remains ‘an abominable mystery’A recent study proposed a hypothetical “first flower”: a prediction of what the flower of the shared ancestor of all flowering plants (or angiosperms) would have looked like. This prediction was based on evolutionary trees constructed from molecular data from 792 modern angiosperms, coupled with physical floral traits for each species, such as number and arrangement of petals and sepals (collectively known as tepals), and whether there were separate male and female, or bisexual, flowers.The resulting “ancestor of all flowers” is a beauty: it is a radially symmetrical flower with several whorls of tepals, each containing three tepals. These surround several whorls of stamens (pollen-bearing male organs), each containing three stamens. In the centre of the bisexual flower are more than five spirally arranged separate carpels (female organs). Quite when this hypothetical flower might have bloomed is a much thornier question. The authors of the study give a (really quite big) window of 140–250m years ago, which reflects the fact that dates for the origin of the angiosperms based on genetic sequence comparisons, employing “molecular clocks”, tend to be much, much earlier than any unequivocal evidence from fossils. Continue reading...

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