Re: HYB: Pollination vectors
From: James Brooks <hirundo@tricon.net>
At 10:13 AM 1/28/99 -0400, you wrote:
>From: Bill Shear <BILLS@hsc.edu>
>
>James--interesting ideas, but please remember that a visit to a flower to
>gather nectar may not result in pollination if the flower is not
>anatomically adapted to be pollinated by the visitor. Hummingbirds have
>been seen visiting spuria flowers, but taking the drops of nectar that are
>found at the petal bases. They can do this without entering the flower at
>all.
The sunbirds of Afroasia that I mentioned are flower peckers and play no
role in pollination either. Pretty clearly the structure of most iris
(including all bearded) is best suited for insect pollination, an
evolution, I assume based upon what pollinators best served the plant.
With I. fulva and some other LA species we begin to see the evolution of
the style arm, a structure modifying that pathway to the nectar into a
shape that is suitable for hummingbird pollination. Hey, guess what,
Louisiana is rich in Hummingbirds, gaining quite a fair number of western
species, and thereby different bill lengths and shapes.
I am sure that a hummer in a flower garden will at least show some
curiosity, particularly if drawn there by a feeder. I hang a piece of
surveyor's tape from the feeder, and they will come along and check it out
for a crevice where nectar might be before discovering the feeding tube, if
they are new to feeders (juveniles, especially). I'm thinking that I. fulva
is a flower in evolution, both in color and form, to hummingbird
pollination, a process which may never be completed since man took over the
natural process and began hybridizing - but since some pretty striking reds
have come out of these efforts, and with well-defined style arms, it will
be interesting to see what the hummers do with it.
Also, red or reddish coloration is not a definitive clue to bird
>pollination,
What in the natural sciences is definitive? Hummers are estimated to have
binocular vision ranging from 1.4X to 8X, and their sense of smell is about
the same as bees or humans, also attractive factors.
because the flower may also be reflective in ultraviolet, thus
>making it attractive to insects.
But if hummers are drinking nectar from it....
Since iris is centered in the ultraviolet side of the spectrum, I suspect
they will get almost no hummingbird visits unless attracted by fragrance
while working more congenial colors. Hummers will work orange, yellow,
pink, and sometimes even white flowers. Whites, of course, favor night
flying moths.
It might be interested to take some
>pictures of irises on UV sensitive film using a quartz lens (glass filters
>out UV) to see if there are any UV pollination guides present.
I've tried photographing iris with a digital (no flash) camera and all the
purples and lavenders came out blue, indicating a need for a UV filter to
pick up the color? Or perhaps that lens had one built in that did filter it
out? Instead I switched back to film. My Nikkor lenses give excellent color
balance.
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