Double flowered sunflowers

When you look at a sunflower, you’re really looking at a composite of tiny flowers, or florets.  The same is true for asters, daisies, and other members of the composite family of plants.  The colorful “petals” of a sunflower are actually a series of tiny florets, called ray flowers, and the seed-producing dark center is made up of lots of disk flowers.  Together, they join together and function as one large flower that attracts pollinators and produces seed.

Stiff sunflower.  The Nature Conservancy's Platte River Prairies, Nebraska.

This sunflower has two kinds of flowers – ray flowers that look like yellow petals, and small disk flowers in the center.

This is how sunflowers are “supposed” to look.  However, you will occasionally find a sunflower that looks more like a chysanthemum, with yellow ray flowers across most or all of the face of the flower head.  Botanically speaking, this is called “double flowering”.  Horticulturists find and breed double flowering varieties of sunflowers and other composites, and you can find them at many nurseries and other plant stores.

Maximilian sunflower.  TNC Bluestem Prairie, Minnesota.

A double flowered Maximilian sunflower (Helianthus maximiliani) at The Nature Conservancy’s Bluestem Prairie in Minnesota.  Most of the disk flowers have been replaced by ray flowers.

When we were in Minnesota a few weeks ago, we saw a fair number of double flowered Maximilian sunflowers at The Nature Conservancy’s Bluestem Prairie.  I don’t remember seeing so many examples in one prairie before, but maybe I just haven’t paid close attention.  The abundance of them made me curious to learn more, so I did a quick internet search when we got back to Nebraska, and emailed a few botanist friends for more information.  The best information I found was related to a 2012 PLos Genetics journal article in which scientists described their discovery of the particular mutation that causes double flowering to occur.  You can read descriptions of the research here and here.

Maximilian sunflower.  TNC Bluestem Prairie, Minnesota.

Extra “petals” can be awfully pretty.

You might think of genetic mutation as something bad, but mutations are actually very common and mostly benign (and don’t affect form or function).  Now and then, a mutation can cause serious problems for an organism, but other times it can generate variations in a DNA sequence that turn out to be advantageous.  Double flowering seems to be somewhere in the middle.  On one hand, producing fewer disk flowers means the plant has fewer opportunities for pollination and seed production.  On the other hand, extra ray flowers could make a plant more attractive to insect pollinators and increase visitation.  In the case of the Maximilian sunflowers at Bluestem Prairie, the mutation doesn’t seem too disastrous, at least based on the number of plants we saw that have the trait.

I’m glad – it sure is pretty.

Photo of the Week – July 30, 2015

During our trip to the Grassland Restoration Network workshop in Minnesota last week, several of us got up early enough to catch sunrise at The Nature Conservancy’s Bluestem Prairie on two beautiful mornings.  I shared a few photos from those outings last week, but thought I’d post a few more today.  I’ve got lots more…it wasn’t hard to find subject matter to photograph!

Leadplant and wildflowers.  TNC Bluestem Prairie, Minnesota.

Leadplant (Amorpha canescens) and other wildflowers abound on The Nature Conservancy’s Bluestem Prairie near Glyndon, Minnesota.

Woundwort (Stachys palustris).

Marsh hedge nettle, aka woundwort (Stachys palustris).

The cool dewy morning allowed me to get pretty close to this resting monarch butterfly...

The cool dewy morning allowed me to get pretty close to this roosting monarch butterfly…

Beetle on Flodman's thistle.  TNC Bluestem Prairie, Minnesota.

This beetle was feeding its way across the top of this Flodman’s thistle (Cirsium flodmanii) – at least I think that’s what I think the thistle species was… it’s always dangerous to guess when I’m far from home.

Common milkweed.  The Nature Conservancy's Bluestem Prairie - Minnesota.

Common milkweed flower buds can be just as attractive as the open flowers…

Bee on milkweed.  TNC Bluestem Prairie, Minnesota.

This bee spent the night on a milkweed leaf and wasn’t quite warm and dry enough to fly off when I spotted it.  If you look carefully, you can see pollinia stuck on two (maybe three?) of its feet.  If you’re not familiar with the fascinating (and unlikely) story of how milkweed is pollinated, you can learn more here.

Purple coneflower (Echinacea angustifolia).  The Nature Conservancy's Bluestem Prairie - Minnesota.

Purple coneflower (Echinacea angustifolia).  This is a species we don’t find very often in the Platte River Prairies (though it’s fairly common nearby) so I always enjoy seeing and photographing it when I can.  As with other “composite” flowers, coneflowers are actually collections (composites) of two kinds of flowers – the ray flowers that look like petals and the disk flowers in the center.  Occasionally, as in this case, a genetic signal gets crossed and ray flower pops up where a disk flower should be.

If you find yourself traveling to or through northwestern Minnesota (just east of Fargo, ND), I encourage you to make the time to visit Bluestem Prairie Scientific and Natural Area.  You can find directions and more information on the site here.  The Nature Conservancy owns about 6,000 acres of prairie there, and their ownership is bolstered by several other tracts of conservation land right next door.  The prairie hosts nesting prairie chickens and beautiful tracts of northern tallgrass prairie.  It’s worth the trip to see it.