Michigan's Rare Goldenrods

Saturday February 18, the Biodiversity Club attended the Michigan Botanical Club’s meeting at Grand Valley State University, where Dr. Pam Laureto,  PhD and Biodiversity Club advisor, gave a presentation on Michigan's rare Goldenrods and her research regarding Houghton's Goldenrod and the naming of a new species: Voss's Goldenrod.  The following are notes from her presentation:

Michigan’s Rare Goldenrods – Dr. Pam Laureto – MCB-WPC past MBC president, current MBF President

Goldenrods belong to genus Solidago L. and family Asteraceae.  Solidago comes from Latin words “to become whole” because of supposed medicinal properties.  About 100 species: most are North American.  There are 23 species of goldenrod in Michigan. 

Goldenrod identification – structures used for identification: the “head” (the capitulum) is made of many inflorescence – outer disc florets are “perfect both male and female while inner florets are pistilate (only female parts).  Goldenrods are self-infertile plants.  At the base of the floret is the achene which is the fruit holding the seeds.  The involucre is made of the phyllaries which are shingle-like structures enclosing all of the florets.  Heads are part of a large structure called the capitulescence (an inflorescence of an inflorescence).  The different capitulescence shapes are: flat-topped, racemiform, or paniculiform, which contains open-lax, wand, club, axillary, pyramidal, and nodding shapes.

Growth form can also be used for goldenrod identification – positions of basal leaves, basal rosette, mid-stem leaves, upper stem leaves, and position of capitulescence all are used to determine a goldenrod’s species.

Note: GOLDENRODS DO NOT CAUSE HAY FEVER!  They are insect pollinated ( an important food source of nectar and pollen for insects), not wind-pollinated.  Their pollen is sticky and fairly large sized, so it doesn’t blow around in the wind.  Ragweed causes fall allergies, not goldenrod.

Some rare goldenrods:

Solidago albopilosa – White-haired Goldenrod.  It only exists in 3 counties in KY, and is nationally recognized as a rare species. 

Solidago shorttii – Short’s Goldenrod, only 13 known populations in the Ohio River area; federally recognized as endangered. 

Solidago spithamaea – Blue-ridge Goldenrod.  It lives in rock outcroppings in Blue Ridge Mountains of TN and NC, and is federally recognized as a threatened species.

Solidago houghtonii – Houghton’s Goldenrod, another federally threatened species.  Lives mostly in Michigan and Ontario, with 1 population in NY. 

Douglass Houghton (1809-1845) discovered a new species of Goldenrod on August 15^th 1839.  Houghton’s Goldenrod has a flat-topped inflorescence, short rhizomes, grows in clumps of many individuals that are all clones, and has a basal rosette of leaves.  An individual lives about 10-12 years, and flowers the 2^nd year of growth and then every other year.  An individual can produce new lones each year to keep genetics going for years after parent plant dies.  It mostly grows in the upper Michigan area near the northern parts of the great lakes, Lake MI and Lake Huron.  Growth patterns associated with the Niagara Escarpment because of dolomite limestone (an alkaline substrate) habitat specificity.  There are about 70 known populations, but some populations contain only a few individuals.

It is an allohexaploid species: Houghton’s Goldenrod has 54 chromosomes.  It is a species that is the result of hybridization between two genetically different parent species.  It has 3 different parental species involved:  S. ohioensis, S. ptarimcoides, and S. riddellii.  Solidago houghtonii likely formed only once. 

NEW SPECIES: SOLIDAGO VOSSII – Voss’s Goldenrod, Pringle and Laureto, 2010. This was discovered in central northern MI, Crawford county.  Dr. Voss noted this plant as being Houghton’s Goldenrod.  Jim Pringle felt that it was morphologically different from Houghton’s.  It was found to have 72 chromosomes – octoploidy.  Dr. Laureto picked up the work from there and followed it through up to naming the species and publishing in the MI botanical in 2010.  Growth patterns associated with the alkaline wet prairie fens by Lake Maurgarete.  Vossii is the only octoploid species of goldenrod.

The lecture was absolutely fascinating, and all of the members who came out to hear it were rewarding with  a very interesting presentation!