Monday, March 7, 2011

Wild aronia plants in the US

      After an on-site aronia consultation with clients in Wisconsin, I drove back home to Iowa.  Driving along enjoying the scenery, I remembered that southwest Wisconsin is one of the areas where Aronia melanocarpa is native.  So I started looking for aronia plants in the rapidly passing landscape.  But the identifying characteristics of aronia plants are not distinctive, especially in July.  When viewed from a moving vehicle at a distance, identifying aronia plants was nearly impossible.  I would need to stop the car and get out for a closer search. 
 

Wild Aronia melanocarpa plant in Wisconsin
      Even though I lived in Madison, Wisconsin for several years while earning my Ph.D., I have never driven across the southwestern part of the state.  Highway 21 is a narrow, flat, stretch of road.  Making good time, I sped by a large rock outcropping.  Immediately, I did a u-turn and pulled into Ship Rock wayside.

Ship Rock
    This impressive geologic formation is on the Richfield-Preston Township line in Adams County.  It is located about one mile west of Richfield and about three miles east of Preston.  Ship Rock is also known as Preston Rock.  

    I learned that several natural rock formations once stood as islands in Glacial Lake Wisconsin.  This long-gone lake was originally formed by the melting ice sheet about 12,000 years ago.  The glaciers did not extend into Adams County but the melt waters did.

      After parking on the south side of the impressive formation, I walked around to the north side admiring and taking photos of the plant communities along the way.  Ferns and other shade-loving plants are abundant on the cooler north side of Ship Rock.

Ferns & mosses on north side of Ship Rock

      As I came around to the sunny south side, I immediately noticed that the temperature was hotter and the light was much brighter.  Clambering through the maze of large boulders strewn at the base of the formation, I nearly stumbled over several wild aronia plants.

Aronia plant on south side of Ship Rock

      They were growing in the accumulated rock debris at the base of the formation.  It appeared to be a high, dry habitat but I suspect moisture percolated up through the sandy soil between cracks in the rock.  This may be a bog-like site, perfect for aronia.  

      My experience confirms that aronia grows best in full sun.  Native aronia plants and aronia cultivars grow best in full sun.  The heat of a south facing exposure does not seem to bother them.  They can also tolerate occasional drought when well established.  In recent years, most of the original native habitat of Aronia melanocarpa has been lost to field crops and urbanization.


      Aronia plants will persist in semi-shade but they will languish or die if the site is too shady.  In a shady site aronia plants grow slower, flower less, and produce little if any fruit.  Aronia is not an understory shrub but they will grow on the sunny edge of a woodland.  Native aronia plants are often found growing in swamps or damp soils in natural openings in woodlands.

      Aronia cultivars that have been selected for fruit production are larger, more robust plants than native plants of Aronia melanocarpa.  The cultivars also tolerate a wider range of soils and growing conditions than the species.

      Plant distribution maps indicate that wild populations of Aronia melanocarpa are quite common in southwestern Wisconsin.  I wonder if these aronia populations started growing there soon after the glacial ice sheet melted abo
ut 12,000 years ago.  Had a Paleo Indian man stood exactly where I was posing for this digital photo?



      To learn more about aronia, visit our website Everhart Horticulture Consulting.
   
      Thank you,
      Dr. Eldon Everhart

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