Riddell's Goldenrod is an erect native perennial forb growing 1-1/2 to 4-1/2 feet high on smooth thick unbranched stems.
The leaves are alternate, narrowly lance-like with smooth edges and pointed tips. The lower leaves are long (10x as long as wide), tapering to a winged stem. The upper leaves become stalkless to actually sheathing the stem. All leaves are usually folded along the midrib (forming a 'V-shaped' cross section). The longer basal leaves and many of the stem leaves are usually recurved. Leaf margins show very fine hair. Lower leaves may have withered by flowering time, especially in dry years.
The floral array is a somewhat flat-topped branched cluster composed of smaller cymes with the cluster stems and flower stalks frequently having fine hair. Depending on the robustness of the plant there may be 30 to over 400 flower heads.
Flowers: Flowers are very small, like most goldenrods, and composed of two types of florets: An outer ring of 7 to 9 yellow ray florets which are pistillate and fertile. These surround 6 to 10 disc florets which have tube shaped yellow corollas with 5 pointed lips that flare outward and reflex when in flower. The disc florets are bisexual and fertile. Disc florets have 5 stamens which surround and are appressed to the single style. The style has a lanceolate shaped (broadest in the lower half) appendage which is exserted beyond the corolla tube when the floret opens. The flower head is enclosed with 3 to 4 series of yellow-green phyllaries that are of unequal length, broad with rounded tips and without hair.
Seed: Fertile flowers produce a dry cypsela shaped like a narrow inverted cone, 1.5 to 2.2 mm long, with several longitudinal ridges and with a whitish fluffy pappus attached for wind dispersion. Seeds of Solidago usually require 60 days of cold stratification and light for germination. They should be surface sown.
Habitat: Riddell's Goldenrod grows from a fibrous root system that develops woody branching caudices which with age will shoot up multiple stems. It prefers moist calcium rich soils such as wet prairies, meadows, marshes etc. Full sun is preferred but it will flower in partial shade. It has been known to hybridize with Stiff Goldenrod, S. rigida. Studies by the Chicago Botanic Garden indicate it is usually free from powdery mildew but the woody caudices are susceptible to winter damage.
Names: The genus Solidago is from the Latin solido, to 'make whole' as the plants of this genus were known to "make whole". (see bottom of page for medicinal lore). The species name riddellii is an honorary for John Leonard Riddell (1807-1865). Some references place this species in the genus Oligoneuron based on the work of G. L. Nesom. The authoritative Flora of North America does not accept this based on anatomy and DNA studies by Zhang, Semple, Noyes, Rieseberg, Beck and others. Minnesota authorities at the U of M and the DNR follow the Flora. This is a wonderful and stately goldenrod that grows well in Minnesota and more people should plant it.
The authorship of the plant classification -Frank ex Riddell- is most interesting. The first to publish this species, ‘Frank’, refers to Joseph C. Frank ( - 1835), German Botanist who was sent to North America to travel and collect specimens for a German botanical society, the name of which has been lost. While in Cincinnati, he became acquainted with John Leonard Riddell and having discovered a new goldenrod species in his Ohio travels, he named it Riddell’s Goldenrod in Riddell's honor. Frank had published in Germany Rastadts Flora and in the United States he studied grasses and sedges, of which Eragrostis Frankii is named for him. His classification work on Solidago riddellii was later updated by ‘Riddell’, which refers to the very same John Leonard Riddell, (1807-1865), American chemistry professor, botanist, writer, and medical doctor. He was born in Massachusetts, but most of his botanical observations were in the central states from Ohio southward. His important work was a “Synopsis of the Flora of the Western States” defined in that era as the territory from the Allegheny mountains to the Platte River in Missouri Territory. It was in great part a compilation. He later published Catalogus Florae Ludovicianae. He served as Adjunct Professor of Chemistry and Lecturer on Botany in the Cincinnati Medical College where he also received his M.D. and he later became chair of the Chemistry Dept. in the Medical College of Louisiana (which then became the University of Louisiana), which position he held until his death. It was there he invented the binocular microscope. The plant genus Riddellia was named for him. Two other plants in Eloise Butler also bear Riddell’s name - Sky-blue Aster and Snow Trillium.
Comparisons: The leaves of Riddell's Goldenrod are somewhat grass-like in shape but larger than most grass and the closest other species would be Grass-leaved Goldenrod, Euthamia graminifolia, but there the leaves are very thin, not folded, are sparsely gland-dotted, and do not sheath the stem and also the number of ray florets is much higher - 17 to 22.
Above: The floral array is a somewhat flat-topped branched cluster of smaller cymes. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: 1st photo - Detail of individual flowers showing the disc floret corolla lobes that flare outward and reflex when in flower. 2nd photo - The yellow-green phyllaries are broad with rounded tips. Note the lanceolate shaped appendage on the styles of the open florets.
Below: 1st photo - Riddell's has a smooth, thick unbranched stem. Note the recurved leaves. 2nd photo - The floral array is a somewhat flat-topped branched cluster of smaller cymes. 3rd photo - Upper leaves sheath the stem and all are folded upward along the mid-vein.
Below: 1st photo - The leaf underside shows very fine hair on the leaf margin. 2nd photo - The root of Riddell's is fibrous and develops a woody branching caudex.
Below: Lower stem leaves are over 10x as long as wide with a winged stalk.
Below: The seed is a dry cypsela shaped like a narrow inverted cone, 1.5 to 2.2 mm long, with several longitudinal ridges and with a whitish fluffy pappus attached for wind dispersion.
Notes: Riddell's Goldenrod is not indigenous to the Garden. It was first planted by Eloise Butler on Sept. 3, 1914 with plants from Minnehaha Park and on Oct. 3, 1914 with plants from Fort Snelling, Minneapolis. in Aug. 1917 she planted 3 from a meadow near the Parkway Bridge of the Luce Line RR. More in 1918, '19, and '20 from various places. Eloise continued to add it in 1921, '22, '23, '26, '27, and '28. In 1946 Martha Crone noted finding it growing in the Garden wetland; she planted it in 1947 and 1953 and it was listed on her 1951 plant census. It was not listed on the 1986 census, but Gardener Cary George planted it again in 1993. In North America it is found only in 12 central states with the Dakotas on the west, Ohio on the east and Arkansas on the south. In Canada it is known only in Manitoba and Ontario and generally considered rare or vulnerable in Canada. Within Minnesota it is found in counties that are generally in the southern half of the state plus counties near the border with North Dakota. There are many exceptions within that area; it is generally known in the core metro counties. There are 18 species of Solidago known in the wild in Minnesota.
Medicinal Lore: The genus Solidago has several species whose leaves and tops were used by natives for sickness of the stomach - usually a teaspoon of leaves to a cupful of boiling water. Hutchins (Ref. #12) mentions several other uses. Here in Minnesota, Frances Densmore (Ref.#5) reported that the Minnesota Chippewa used various species of Goldenrod, for treating cramps, fevers, colds, ulcers and boils. Mrs. Grieve (Ref. #7) reports on European use of various species.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"