Leaf of the day: More Crown Flower Sketches and Study

Today more sketches of the Crown Flower, trying to concentrate while I listen with growing dismay to the swine flu reports. I am trying to be optimistic as in a week's time I am due to fly home to the UK for a long visit...most of May. I am so looking forward to it, so I am just thinking positive.

I was looking in more detail at the flower head and the leaves. The structure of the flower is so odd. There are 5 sepals only seen from the underneath of the flower, then 5 petals which do at least look like petals. Then the central "crown" part which consists of 5 stamens, the buttress like structures, which are joined with the filaments to form a structure called a "gynostegium", a fusion of the male and female parts of the flower.
This superb photo of a White Crown Flower by G D Carr from the Hawaii Education dept here shows the top of the crown, where you can see 5 little black points.



These I think are called the glands and if you can get a scalpel in at this point you might be able to extract the "pollinia". These are the structures which hold the pollen, not loose pollen as we usually imagine, but flat waxy pollen drops, in pairs, attached to the gland.

Here is the scan I took yesterday after I had found the pollinia. It is tiny, just 2mm long, but scanning it at high res did give me a reasonable result.


Crown Flower Pollinia

Somehow... and I am still not entirely clear how this works with this particular flower, an insect has to attach one of these to its leg and transport it to another flower.

If you are interested in milkweeds, there is a stunning web page by Brian Johnston with wonderful macro/micro photos and a clear explanation of the intricate process of the pollination of the Common Milkweed Asclepias syriaca here. The milkweed structures are all basically similar but I think I might email him to ask if he can explain exactly how it works with this particular flower... How does the insect (probably one of the red milkweed bugs) get these particular pollen sacks on its leg???. I had to work quite hard to get the thing out, but then, as we say in Lincolnshire, I probably wasn't holding my mouth right.. :)
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More Crown Flower Sketches