Sunflower Party Time!

Plains sunflower (Helianthus petiolaris). This species is dismissed by many as a roadside or cropfield weed.

Sunflowers are seen by some people as big beautiful flowers, and by others as big ugly weeds.  Regardless of aesthetic opinions, however, sunflowers appear to be pulling their weight, and more, in the ecology of the Nebraska sandhills prairies this year.  After a long dry year, there’s not much green, let alone blooming, in the sandhills right now.  The biggest and most obvious exception is the plains sunflower (Helianthus petiolaris).

Plains sunflower, an annual, is one of the few flowers still blooming in the dry sandhill prairies this summer.  Most other plant species have already gone dormant.

While most other plants have given up on this year’s growth because of the very low soil moisture, these annual sunflowers are acting like it’s party time.  I imagine the long taproot helps the plant get deep moisture, but its root system isn’t any bigger or deeper than many other sand prairie plants, which sit brown and withered in the surrounding landscape.  Of course, being annual plants, plains sunflowers don’t really have the option that perennials do to just shut down for the remainder of the season during stressful years.  Once a plains sunflower seed germinates, it’s got exactly one growing season to flower and make seeds before it dies.  If it had a motto, it would be something like “Live like there’s no next year!”

A bee fly feeding on a plains sunflower.

.

I’ll bet this fly is grateful for sunflowers.

There are a lot of insect and other species that should be awfully thankful for the ostentatious blooming of the sunflowers this year.  Sunflowers are probably the only thing keeping most pollinators alive at the moment, for example.  That’s great for those pollinator species, of course, but also for the predators and parasitoids that live of those insects. 

A cuckoo wasp rests on an annual sunflower.  These wasps lay their eggs in the nests of solitary bees, and the wasp larvae hatch and devour the young bee larvae and their provisioned food.  Thanks to Mike Arduser for the identification.

.

This grasshopper is probably more glad about the green foliage than the flowers – although it may feed on the flowers as well.

.

An ant on a sunflower petal. While it makes a good photo, I don’t think the ant was actually interested in what was on the front of the flower.

Ants have their own reasons for appreciating sunflowers – largely independent of the big showy flowers.  Sunflowers produce and excrete sweet sticky sap (known as extra-floral nectar) that attracts hungry ants.  It’s thought that attracting ants in this way might help repel herbivorous insects that might otherwise feed on the sunflower’s leaves and stems.  Ants are not predators to mess with if you’re a hungry caterpillar or other plant-eating insect… 

You can read more about prairie ants here

Ants collecting extrafloral nectar from the backside of a sunflower blossum.

.

The density of ants on some sunflowers was pretty impressive. I’m not sure if this is out of the ordinary because other food sources are limited, or if I was just noticing more of them because there wasn’t much else to look at…

.

This assassin bug (a predator) is also taking advantage of the attractiveness of sunflowers to other insects.

.

Not only are the sunflowers stil blooming – there are more flowers yet to come! What an amazing plant.

While sunflowers are filling an important role this time of year, that importance might actually increase this fall and winter.  The seed crop for birds and other wildlife is going to be pretty paltry this year.  Sunflower seeds are always a favorite of migrating and wintering animals, but this year, they will be especially critical.  So – party like there’s no tomorrow, sunflowers.  And, on behalf of the inhabitants of the sandhills prairies… thank you!

.

In Celebration of Annuals

 

When most people think about prairie plants, they think about long-lived perennial grasses and wildflowers.  However, 20-25% of plant species in most prairies are annuals; germinating, flowering, and dying in the same growing season.  Some of those annuals are tiny uncommon species that take advantage of small openings or disturbed areas when they can.  Others are adapted to growing conditions (e.g. saline or alkaline soils) that most other plants can’t grow in, and thrive because of a relative lack of competition.

Eustoma grandflorum is a member of the Gentian family, and is known in Nebraska as "Prairie Gentian". This annual plant has purple to white flowers and can be found in moist prairies throughout much of the Great Plains (we often find it in relatively alkaline soils). Its showy nature has led to the creation of horticultural varieties as well.

Most of the best known native annuals, however – think of annual sunflowers, annual ragweeds, and similar species – are largely considered to be weeds.  Because they can quickly become startlingly abundant, they get lumped in with non-native weeds such as buttonweed, exotic pigweeds, lamb’s quarters, and others, that are cropfield pests.  However, that label of “weed” is unfair for most of those annuals (including some of the non-natives).  A better term is “opportunistic”.  And thank goodness for them.  They fill spaces that are opened when the perennial plants around them are weakened, giving herbivores and pollinators something to eat, providing food and cover for wildlife, and helping to stave off true weeds that can take advantage of the same kinds of conditions. 

 

Plains annual sunflower is on of two annual sunflower species in Nebraska (the majority are perennials).  Plains sunflower inhabits sandier soil than its relative Helianthus annuus.  Both are considered cropfield pests but are also very important components of prairie plant communities.

In our Platte River Prairies, we work to ensure that we harvest seed from as many native annuals as we can each year so they can establish and create a seed bank in our restored prairies.  We do this, in part, because they are native species and part of the prairie community.  However, we also include them because they are a better alternative than some of the invasive species that compete for the same spaces.  We also watch for those annual plants and monitor their ebbs and flows in abundance to help measure whether or not we’re creating open spaces for germination and establish of annual and perennial plants alike.  When I see abundant annuals in our prairie, I know that there are perennials getting an opportunity to spread as well – they’re just not as showy about it.

Woolly plaintain (Plantago patagonica) is an abundant annual in distrubed sandy soils. The small grass seen growing with is is another annual, six-weeks fescue (Vulpia octoflora). We harvest as much seed from both species as we can for our sand prairie restoration work because the two species inhabit the same habitat as exotic annual bromes, and we'd rather have the native species!

These are just a few of the many annuals found in the Nebraska prairies we restore and manage.  They’re not any less interesting than perennial plants – just shorter-lived.  If anything, their short spectacular lives (they HAVE to bloom and produce seed in their single year of life in order to ensure a next generation) with abundant flowers and seeds make them underdogs that are easy to root for.  Go annuals!

Saltwort (Salicornia rubra) is one of several annual plant species that can thrive in very saline soil conditions. In Nebraska it is limited mainly to the saline wetlands around Lincoln, Nebraska and is a state-listed species. It is a succulent plant and tastes like sea water when chewed.

 

Western rockjasmine (Androsace occidentalis) is a tiny annual plant in the primrose family. Found in much of the western 2/3 of the United States and Canada, it is often difficult to see unless one is looking for it. It is relatively common in Nebraska (though usually overlooked) but is a state-listed threatened/endangered species in Indiana, Michigan, and Ohio.

Deer vetch (Lotus unifoliolatus), aka prairie vetch, is a very common native annual legume in our prairies along the Platte River. It becomes very abundant following grazing, summer fire, or drought.