A-Z of botany: Apomictic
Just for a change, since I am not doing much in the garden except clearing, I thought I would do a series in between the regular posts on interesting botanical and gardening words. Today: Apomictic.
Apomixis is the way that some plants produce fertile seeds without a combination of the genes of two parent plants. So the flowers open as usual but the seeds are produced without needing pollen from another plant or flower (or even from the same flower) and so the seeds produce plants that are genetically identical to the parent. As such they could be regarded as clones, something gardeners are familiar with when plants are reproduced by cuttings, grafting, division or micropropagation.
Quite what the advantage is I can’t work out. In the case of dandelions, it means that if the plant is well suited to the environment, the identical progeny will be too without the risk of changes caused by mixing the genes. But when you consider that so many plants go to huge effort to avoid even self pollination then it seems odd. And dandelions have flowers that attract lots of pollinators – all very strange. Blackberries and sorbus are other common plants that do this, meaning that if you collect seeds from your sorbus tree the offspring should be identical.
Note that this is not the same as how cucumbers and bananas make fruits without pollination. That is parthenocarpy and is the formation of the fleshy fruits but without seeds.
Because apomixis is similar to cloning the term can also refer to the condition when flowers on a spike are replaced by plantlets or bulbils. Called vegetative apomixis, it occurs on lilies, some grasses and also on some agaves where the flowers are replaced by tiny plants.
Does that mean than dandelions, sorbus, brambles never cross polinate, or just sometimes. How do variations come about? Very interesting, and new to me.
Brambles and dandelions at least have populations that are called micro-species with lots of identical individuals. I assume that although they are pollinated the pollen is not actually used to fertilise the ovaries. but in sorbus and rubus there must be some cross-pollination, at least when we force it to happen, or there would not be hybrids. I am getting a bit out of my depth now! 🙂