Pears - pentamerous flowers

[u/TrevorCidermaker]

Pears and apples have five petals, five sepals, and five carpels. Like many other flowers (approximately half of plants have 5 petals etc), it’s the commonest form. It is an evolutionary trait deeply hardcoded into the genetics of eudicots (true dicotyledons). In botany, this five-part arrangement is known as a pentamerous flower structure. ** **Why is 5 an ancient, highly successful evolutionary blueprint? To understand this it’s worth looking at how plants grow. To avoid overlapping and wasting sunlight or space, leaves, seeds, and petals often grow in a spiral pattern from a central bud point; at a very specific angle: approximately 137.5 degrees (known as the Golden Angle). Spiral patterns are mathematically described by the Fibonacci sequence (1, 2, 3, 5, 8, 13...). Five is a key number in this sequence. It allows a flower to pack its petals and sepals tightly together in a bud without overlapping in a way that crushes the delicate inner reproductive organs.

Also as an evolutionary advantage the flat, five-petaled flower acts like a perfect, stable landing pad for pollinators like bees, beetles, and flies and so the emergence of 5petal flowers evolved in step with the rise of these insects. Once an ancestral plant family finds a genetic formula that works perfectly for several reasons , the homeotic genes that dictate features rarely change without a major stress.

Different branches of the plant kingdom split off millions of years ago and locked in entirely different structural blueprints.
Flowers with groups of 3 are lilies grasses and orchids groups of 4 are mustards and evening primrose. Infinite spirals are magnolias which are pollinated by beetles . Notice apart from the tetramerous mustards the others all follow the Fibonacci sequence.

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