Kay wrote or quoted:
In article , Tim Tyler writes
Kay wrote or quoted:
In article , Tim Tyler writes

Does anyone know why Nasturtium flowers have those strange horn-shaped
bits pointing backwards?

A pictu http://www.andysmall.com/Media/Jpegs/00006.jpg

My best guess so far: flower/bee counter-weight.

Think you know better than that? Please *do* let me know ;-)

Usually because the nectar is buried at the end of it to make sure the
pollinator has to go in a long way for it and gets well and truly
covered with pollen. Not sure if this is the case with nasturtiums -
haven't dissected one to see.

I believe this is not the right answer - since the "horn" contains no
flower stamens - and no pollen. The nasturtium's pollen is clearly
evident elsewhere.

I didn't say the pollen was in the spur! I wondered if the nectar was

[...]

However, Proctor and Yeo "The Pollination of Flowers" seems to suggest
that bees take only pollen from nasturtiums, hence my wondering what it
is pollinates nasturtiums in their natural environment. A close
relative, Tropaeolum pentaphyllum, with a similar spur, is bird
pollinated [...]

You can see how it would work - humming bird feeds its long beak down
the spur to get at the nectar, in doing so getting its feathery body
liberally coated with pollen, which is rubbed off onto the next flower
it meets.

Good detective work after all it seems ;-)

Nasturtiums are indeed naturally pollinated by humming birds:

``Many flowers typically pollinated by hummingbirds, such as nasturtiums,
don't need to be fragrant because their pollination partners have little
sense of smell.''

- http://www.kidsgardening.com/themes/pollinator2.asp

Now the humming bird has been mentioned, the spur's "function"
now seems clear enough - thanks!
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