Thursday, March 1, 2012

More than just a flower

Flowers are not always quite what they seem.  Technically, a flower consists of 4 sets of organs: sepals, petals, stamens, and carpels.  Stamens (pollen-producing organs) and carpels (seed-producing organs) do the work of sexual reproduction, while petals do the all-important job of attracting pollinators with color, nectar, and fragrance.  Sepals typically provide a protective wrapper for young flowers, but sometimes assist in the job of attracting pollinators, or sometimes replace the petals altogether. 

The actual flowers of the Poinsettia are tiny and clustered
within green cups, which themselves are clustered within a
mass of bright red bracts.  Nectar is produced in the yellow,
mouth-like appendages on the sides of the green cups.
Many plants have adopted an alternate strategy in which a colorful display is created, not by the flowers themselves, but by colorful bracts (modified leaves) around them.  Probably the most spectacular example of this is the winter-blooming Poinsettia.  In its native tropical American habitat, the bright red bracts attract migrating hummingbirds to hidden cups of nectar.

In some cases, what appears to be a single flower is a dense cluster of flowers, with specialized, petal-like flowers arranged in a circle around them.  This is the highly successful strategy of the sunflower family.

In the sunflower family, the "flower" consists of a compact head
of flowers, in which the outer circle of flowers (ray flowers)
are most often stretched out into a long petal-like shape.  The
inner flowers (disk flowers) are small and trumpet-shaped, with
five lobes representing the actual petals. Usually these are the
ones that produce the seeds.
In the Anthurium, the actual flowers are
the tiny bumps on the long spadix.
In the equally successful Aroid family (Araceae), a large colorful bract (called a spathe) provides a backdrop for a fleshy spike (the spadix) of tiny crowded flowers.  Bright red Anthuriums are a popular example, as are Calla lilies and Spathiphyllums.

For additional examples of "false flowers,"  I refer you to my article of several years ago in Florida Gardening Magazine:  False Flowers

I also featured two genera of the  Araceae in Florida Gardening articles: Amorphophallus and Calla lilies.

For a nearly complete list of my Florida Gardening articles, and for a link to the website where you can find an index to all of their articles, go to Florida Gardening Magazine.  The magazine is devoted to gardening in Florida, but in my own articles, I often explore more botanical questions.  The magazine is also followed by people in similar subtropical climates around the world.

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