Hiawatha Native Plant Program Successfully Grows Rare Downy Sunflower
The Hiawatha National Forest Native Plant Program has a success story a long time in the making, and it stretches across two districts of the Hiawatha National Forest. It took at least four years for a new population of downy sunflower (Helianthus mollis) on the St. Ignace District to become established and produce a seed source.
Downy sunflower is a medium sized prairie species with a showy yellow flower head. The leaves and stems are covered in soft white hairs, giving the plant its downy appearance. It is a rhizomatous, perennial plant that frequently spreads vegetatively and forms colonies. The plant is found in prairie remnants in open sandy ground, and also occurring in areas along railroads and in savannas. Downy sunflower is listed as regional forest sensitive on the Hiawatha NF and also threatened in Michigan due to the decline in native prairie settings. This species likely requires natural disturbances associated with prairie habitat such as prescribed fire or brush removal to prevent woody plant encroachment. Much of this habitat type has been lost or severely degraded.
The Hiawatha National Forest has only one known natural occurrence of downy sunflower. It is located in a dry sandy forest opening on the old Manistique Ranger district (now part of the Rapid River RD) in the central Upper Peninsula of Michigan. This parent population is pictured below.
The population showed signs of drought and also disturbance from a nearby motorized trail. A few plants that were disturbed were then transplanted to the Munising District office native plant garden. The transplant was a success! The plants multiplied and by the second year the plants produced flowers and seeds. Deb LeBlanc, West Zone Plant Ecologist, collected the seed for the Native Plant Program greenhouse in Marquette, Michigan. It was discovered that the germination rate was very low, only a few of the seeds produced new plants. In 2004, some of the seeds were sent over to the St. Ignace District office in the eastern Upper Peninsula.
The seeds were hand broadcasted in an area of the St. Ignace native plant garden. The area of the garden is in full sun, and contains other prairie species such as compass plant (Silphium laciniatum), blazing star (Liatris aspera), wild bergamot (Monarda fistulosa), and coreopsis (Coreopsis lanceolata). After a 2-year dormancy period the downy sunflower appeared in this location. Success was close at hand, but in the summer of 2007, Michigan experienced a severe drought. Despite the drought, the plants did emerge, but they did not flower. And finally in 2008, perhaps due to abundant rainfall in spring and summer, the plants flourished (see pictures below).
Information from propagating downy sunflower is helpful in learning how to improve techniques for growing other rare or unusual native species. The seeds from this thriving population as well as the population in the Munising native plant garden can now be collected and used to establish more populations in prairie remnants across the forest.
For More Information
Hiawatha National Forest – St. Ignace District Botanist
Hiawatha National Forest – West Zone Plant Ecologist