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Pollination of Iris

A description of the pollination of Yellow Flag
Do you know what other flowers are members of the Iris family?
Some questions and research projects for the careful observer:
The Iris family includes a number of important ornamentals
Glossary
Reference

An excellent, but technical description of the pollination of Iris pseudocorus, Yellow Flag, can be found in Proctor and Yeo, 1972:

"The Yellow Flag (Iris pseudacorus) resembles the Martagon Lily in having multiple tubes giving access to the nectar.  Here, however, there are three tubes instead of six, three of the perianth segments (the 'standards') serving for display only.  The lower side of each tube is formed by the narrow stem, or haft, of one of the other perianth segments (the 'falls'), each of which has a large free blade on which insects can alight.  Lying over the haft of each fall is a greatly expanded and flattened style, looking like a petal and forming the upper side of the tube, and arching over a single anther.  The tube is large enough for the bumble-bees or long-tongued flies which pollinate the flowers to crawl right in. ...the tube is divided into  two narrow channels which contain nectar.  It is clear that the functional unit is not the whole Iris flower, but a third of it; what is particularly interesting is the remarkable analogy between each individual tube and the whole of a Labiate (mint) flower."

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Do you know what other flowers are members of the Iris family?  Check below.  Have a close look at the flowers of these Iris relatives.  Are they also made up of multiple "functional units" like Iris flowers, or just one functional unit, like most flowers?

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Some questions and research projects for the careful observer:

Apparently the beard of a bearded Iris is derived from the anthers.  Do they actually produce pollen, or are they sterile?  
In highly cultivated varieties, is there still nectar available for the bees, or has the nectar been bred out of the flowers?  
Do different varieties of Iris have different amounts of nectar (if the flowers are covered with a bag for a day or two so no bees can steal the nectar away)?  Does this affect the attractiveness of the Iris flowers to bees?
Some Iris varieties are scented, others less so or not at all.  How does the scent of the Iris affect their attractiveness to bees?
Which Iris colors or color combinations receive more bee visitors?  Which less?  Try to compare varieties that are similar in scent and amount of nectar when making these comparisons.
Watch bees visiting individual flowers.  Do they visit all three "functional units" of the flower on a single visit, or just one or two units?  Why do you think they behave this way?
Try adding a few drops of sugar or honey water to a few flowers.  Do bees act differently on flowers with extra nectar as compared with natural flowers without supplemental nectar?

Need more ideas for projects on Pollination?  See the Solitary Bee Web, especially the School Projects page.

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The Iris family includes a number of important ornamentals:

Gladiolus
Crocus (including the species that is used for saffron - which is Crocus pollen!)
Freesia
Sisyrinchium

The rhizome of some Iris species are the commercial source of orris root, used to flavor toothpaste.

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Glossary:

Anther: The part of the stamen that holds the pollen in a flower.

Perianth:  The corolla (petals) and calyx (sepals) of a flower.

Style:  The more or less elongated part of the pistil that is the female part of the flower, i.e. the part of the flower that will become a fruit or pod holding the seeds if pollination is successful.

Reference:
Proctor, M. and P. Yeo, 1972.  The Pollination of Flowers.  Taplinger Publishing Company, NY.
The description of Yellow Flag is on p. 197

Read about the Royal Irises Project, a study of 8 native species of Iris in Israel,  part of Rotem, the Israel Plant Database at Hebrew University of Jerusalem.   Click on "Projects" in the navigation bar.  These Irises apparently are pollinated by male bees.

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Revised Sept. 7, 2000.
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