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Wednesday, March 18, 2015

Mass Appeal and Pollination



Some of the many visitors to goldenrod.  © Beatriz Moisset

Many flowers are not particularly selective; they welcome all kinds of visitors. They are wide open, easily accessible, thus many insects can reach the nectar and/or pollen regardless of whether their tongues are long or short. Such flowers provide a convenient standing platform to save their visitors the inconvenience of hovering over them. Their structure is simple so the pollinators don’t need to figure out how to open them in order to reach their rewards. Goldenrod is a fine example.
Monarch butterfly on goldenrod. © Beatriz Moisset
 I have spent countless happy hours observing goldenrods and photographing their numerous visitors. The one most common in my area is the Canada goldenrod. Several hundreds of species visit their flowers. Bear in mind that not all flower visitors qualify as pollinators. Some are not efficient at carrying pollen, or sit in one place for a long time and never make it to another plant. Such is the case of ambush bugs, whose only concern is to snare hapless pollinators to make a meal out of them. If you are interested on photographing and identifying pollinators this is a good place to start.

Metallic green bee. © Beatriz Moisset
 This plant blooms in the fall. It often gets blamed for allergies, but the real culprit is another plant that grows close by, sometimes intermingled with goldenrods, ragweed. Its flowers are inconspicuous because its pollen gets carried by the wind, not by officious pollinators. This is how it gets into our nostrils and causes our suffering. The much maligned goldenrods have larger, heavier and stickier grains of pollen that cannot get airborne and that require help from visitors.

Two states, Kentucky and Nebraska, have the goldenrod as their state flower. It is not clear which species of goldenrod Kentucky picked, but it is likely the Canada goldenrod (Solidago altissima). Nebraska’s choice is clearer, the giant goldenrod (Solidago gigantea). South Carolina, not satisfied with a state flower, also has a state wildflower. It is the Canada goldenrod. It is worth mentioning that Delaware has a state herb, the anise-scented or sweet goldenrod (Solidago odora).

Bumble bee on sunflower. © Beatriz Moisset

Coreopsis. © Beatriz Moisset
 Two other state flowers also have mass appeal. Like goldenrod, they are members of the daisy or aster family, easy to access by different kinds of visitors. They are Kansas’ sunflower (Helianthus annuus) and Maryland’s Black-eyed Susan (Rudbeckia hirta). It is worth mentioning here that two states, Florida and Mississippi, chose the tickseed (Coreopsis spp.) as a state wildflower in addition to their official state flowers, the orange blossom and the magnolia, respectively.

Kentucky: Goldenrod
Nebraska: Goldenrod
South Carolina (wildflower): Goldenrod
Delaware (herb): Goldenrod
Kansas: Sunflower
Maryland: Black-eyed Susan
Florida (wildflower): Coreopsis
Mississippi (wildflower): Coreopsis

The indiscriminate pollination strategy represented by all these flowers has advantages and also disadvantages. They suffer no shortage of pollinators. If one species is doing poorly one year, as it often happens in the insect world, there are plenty more to fill in the deficiency. However, sometimes too much of a good thing can be bad. Some of these non-specialized pollinators may be visiting a variety of flowers instead of being faithful to just one species so they end up carrying the wrong kind of pollen in such cases.

Blossoms with such mass appeal give me the opportunity to introduce the reader to the main groups of pollinators. They are all well represented on these mass appeal flowers.

Andrenidae bee © Beatriz Moisset
Bumble bee. © Beatriz Moisset
 Let us start by getting acquainted with bees. More than 80 species have been seen on goldenrods. Some of them deserve mention. Bumble bees are larger than other bees, plump, dark with yellow or white stripes, and hairy. Metallic green bees are small and gorgeously colored. They may escape notice if one isn’t very observant; but it is easy to become captivated by their shiny aspect. Mason bees and leaf-cutting bees carry pollen on their underbelly, unlike most other bees that carry it on their hind legs. Most of them are dark, nearly black and about the size of honey bees or slightly smaller.

Wasp. © Beatriz Moisset
 Wasps are related to bees and sometimes people confuse them. Most wasps are less hairy than bees and have narrow waists. They raise their young on a diet of insects or spiders, instead of pollen and nectar as bees do. Adult wasps need nectar to fuel their flight. Thus, they are frequent flower visitors and accomplish some pollination.

Syrphid fly. © Beatriz Moisset
Syrphid fly. © Beatriz Moisset

Many types of flies, including mosquitoes and gnats visit flowers to feed on their nectar. Some are good pollinators. The Syrphid flies, also called flower flies, are among the most assiduous flower visitors. Most of them mimic bees or wasps and are frequently mistaken for them. However, they don’t sting and there is no reason to fear them.

Buckeye butterfly on goldenrod. © Beatriz Moisset
Pyrausta moth on sunflower. © Beatriz Moisset
Yellow collared scape moth on goldenrod. © Beatriz Moisset
 Butterflies, skippers and moths have extremely long tongues that they can use like drinking straws when sipping nectar. They favor long necked flowers and carry pollen from one to another.

Polished lady beetle on sunflower. © Beatriz Moisset
Soldier beetle on goldenrod. © Beatriz Moisset
Finally, beetles, although not well specialized for pollination, are also capable of doing so in special circumstances. We already mentioned magnolia pollination by beetles. They also visit other flowers and can do a reasonably good job in some cases.

In the following chapters we’ll see flowers that have chosen a different strategy. They are pickier or more selective. Some attract a handful of visitors; a few go to the extreme of having relationships with only one species of pollinators.

References
Canada goldenrod visitors in IL. http://eol.org/data_objects/31873000

Monday, March 2, 2015

The Earliest Pollinators: Beetles and Flies

Magnolia © Beatriz Moisset
 By the time the first flowering plants appeared on Earth there weren’t any bees or butterflies. Those superb pollinators would take millions of years to evolve from wasps and moths respectively. So, who would be attracted to flowers? Who would carry pollen?

Other insects, although not adapted to sipping nectar and storing pollen in little baskets, liked to visit flowering plants to eat the pollen. Sometimes, they also devoured the flowers themselves. Beetles and flies were among the earliest pollinators. These two groups of insects visit the flowers of magnolia and water lilies to this day. In general, flowers pollinated by beetles are cup-shaped to allow these insects to stay for some time. They are strongly scented by fruity or rotten smell. The petals may be tough and leathery, helping them to put up with the abuse; many of them are greenish or creamy white.

Tumbling flower beetles on magnolia © Beatriz Moisset
The state flower of Louisiana and of Mississippi is the Magnolia (Magnolia grandiflora) which is an example of some of the oldest flowering plants; it presents all the qualities listed above and it is pollinated by beetles that use the flowers as a singles bar. They stay for hours eating, drinking, mating and making a mess of the place. When they arrive, usually only the female part of the flower is mature enough, so if they carry pollen from other flowers they get cross-pollinated, but by the time the beetles leave, the stamens or male parts have become ripe. The visitors get easily dusted with it and ready to carry it to the next awaiting singles bar. Beetles and flies find a coating of nectar covering the petals that they can slurp as they go along.

Dance fly on Magnolia © Beatriz Moisset

It is worth mentioning here the tulip tree (Liriodendron tulipifera) because it is the state tree of Indiana, Kentucky and Tennessee. The state flowers of Indiana and Tennessee are not native; they are the peony and iris, respectively, so I like to think of the tulip tree blossom as the honorary state flower of these two states. The tulip tree is a relative of magnolias, equally ancient; its flower bears some resemblance to magnolias. It is also pollinated by beetles, although bees and other insects also contribute to its pollination.

Another ancient flower, the California poppy (Eschscholzia californica), California’s state flower is also pollinated by beetles in some instances. These are more numerous than bees in arid areas. Several species of bees, including honey bees also pollinate these flowers.

California poppy © Audrey. Flickr
State flowers that illustrate the earliest pollinators:
Louisiana: Magnolia
Mississippi: Magnolia
California: California Poppy

Once plants came up with this novel solution to their fertilization process, there was no stopping them. Evolution accelerated and an ever growing variety of flowering plants emerged from the older lineages. In turn, more insects evolved to take advantage of this resource. This is how some carnivorous wasps went vegetarian. They became what we now know as bees. Pollen and nectar supplied all their needs.

Also some moths developed a taste for nectar during their adult life. Unlike most moths, they were diurnal and often sported fancy colors. In other words, they evolved into butterflies. Being frequent flower visitors they became pollinators. This is not to say that wasps and moths, the predecessors of bees and butterflies don’t pollinate. In fact some of them are valuable and are highly specialized ones.

The following posts deal with these pollinators and their flowers.  We will start with the ones who invite a wide assortment of guests. They have mass appeal and several state flowers illustrate this nicely.

Pollinators of Official State Flowers 
Mass Appeal and Pollination