.... and for small solitary bees like those above. Can anyone help me identify any of these?
It might seem that this is a perfect example of a partnership between plant and pollinator, with generous rewards for services rendered by the insects, but this is a very one-sided relationship. Unlike typical flowers, most dandelions don’t actually need any pollen to set seeds.
Seeds are usually produced when male pollen fertilises a female egg cell inside the flower to produce an embryo inside of the developing seed, but in many dandelion species seeds are produced without the need for fertilisation, so the seedlings are genetic clones of the mother plant. All that pollen and nectar that sustains the bees, as well as the elaborate mechanism for presenting pollen to bees to maximise the chances of cross pollination, is redundant as far as the dandelion is concerned - a needless expense.
This production of seeds without pollination is called apomixis and in recent years it has attracted the interest of genetic engineers, because if it could be enginerred into GM crops they wouldn't require pollen for seed production. This would remove one major objection to these high-tech crops – that they can transfer their genes via pollen to organic crops or wild plant relatives. Without pollen, an apomictic crop could not contaminate non-GM crops, with the added bonus that it could reliably produce seeds without depending on insect pollinators.