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.

 
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About Chris Helzer

Chris Helzer is the Director of Science for The Nature Conservancy in Nebraska. His main role is to evaluate and capture lessons from the Conservancy’s land management and restoration work and then share those lessons with other landowners – both private and public. In addition, Chris works to raise awareness about the importance of prairies and their conservation through his writing, photography, and presentations to various groups. Chris is also the author of "The Ecology and Management of Prairies in the Central United States", published by the University of Iowa Press. He lives in Aurora, Nebraska with his wife Kim and their children.
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4 Responses to In Celebration of Annuals

  1. Stephen Winter says:

    Good post Chris. Some of the annuals make me wonder. My prairie world-view is like what you alluded to in the post – tallgrass prairie is a perennial system where the dominant perennial grasses rule the roost, so to speak. The extreme dominance of the perennial grasses makes sexual reproduction a relatively rare event, so most of the species reproduce asexually (discussed in one of your previous posts?). Why then, are some annuals like flax (Linum) or deer vetch be so abundant? How are they able to escape the competitive influence of the dominant perennials when so many other species can’t?

  2. Pingback: Photo of the Week – April 13, 2012 | The Prairie Ecologist

  3. Richar says:

    Wonderful article and as I read I kept hoping a list of these annuals would scroll up but, sadly no more than two or three species named, what a cliff hanger! Any reference material with such a list would be thrilling to encounter, thanks in advance.

  4. Jackie Orelski says:

    Great article! I crave any information on growing native. Recently read a book on sustaining wildlife with native plants, by Douglas W. Tallamy. He stated: “……..it will be the plants that we use in our gardens that will determine what nature will be like in 10, 20 and 50 years from now.” (including prairies) Thanks Chris!

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