Solidago, commonly called goldenrods, is a genus of about 100 to 120 species of
flowering plants in the aster family, Asteraceae. Most are herbaceous
perennial species found in open areas such as meadows, prairies, and savannas.
They are mostly native to North America, including Mexico; a few species are
native to South America and Eurasia. Some American species have also been
introduced into Europe and other parts of the world.
Description Solidago species are perennials growing
from woody caudices or rhizomes. Their stems ranges from decumbent to ascending
or erect, with a range of heights going from 5cm to over a meter. Most species
are unbranched, but some do display branching in the upper part of the
plant. Both leaves and stems vary from glabrous to various forms of pubescence.
In some species, the basal leaves are shed before flowering. The leaf margins
are most commonly entire, but often display heavier serration. Some leaves
may display trinerved venation rather than the pinnate venation usual across
Asteraceae. The flower heads are usually of the
radiate type but sometimes discoid. Only ray florets are female, others are male,
hermaphroditic or entire sterile. Head involucres are campanulate to cylindric
or attenuate. Floret corollas are usually yellow, but white in the ray
florets of a few species; they are typically hairless. Heads usually
include between 2 and 35 disc florets, but in some species this may go up to
60. Filaments are inserted closer to the base of the corolla than its middle.
Numerous heads are usually grouped in complex compound inflorescences where
heads are arranged in multiple racemes, panicles, corymbs, or secund arrays.
Solidago cypselae are narrowly obconic to cylindrical in shape, and they are
sometimes somewhat compressed. They have eight to 10 ribs usually and are
hairless or moderately hispid. The Pappus is very big with barbellate
bristles. The many goldenrod species can be
difficult to distinguish, due to their similar bright, golden-yellow flower
heads that bloom in late summer. Propagation is by wind-disseminated
seeds or by spreading underground rhizomes which can form colonies of
vegetative clones of a single plant. They are mostly short-day plants and
bloom in late summer and early fall. Some species produce abundant nectar
when moisture is plentiful, or when the weather is warm and sunny.
Use and cultivation Young goldenrod leaves are edible.
Native Americans used the seeds of some species for food. Herbal teas are
sometimes made with goldenrod. Goldenrod is often unfairly blamed for
causing hay fever in humans. The pollen causing these allergy problems is mainly
produced by ragweed, blooming at the same time as the goldenrod, but is
wind-pollinated. Goldenrod pollen is too heavy and sticky to be blown far from
the flowers, and is thus mainly pollinated by insects. Frequent handling
of goldenrod and other flowers, however, can cause allergic reactions, sometimes
irritating enough to force florists to change occupation. Goldenrods are
attractive sources of nectar for bees, flies, wasps, and butterflies. Honey
from goldenrods often is dark and strong due to admixtures of other nectars.
However, when honey flow is strong, a light, spicy-tasting monofloral honey is
produced. While the bees are ripening the honey produced from goldenrods, it
has a rank odor and taste, but finished honey is much milder.
Goldenrods are, in some places, held as a sign of good luck or good fortune.
They are considered weeds by many in North America, but they are prized as
garden plants in Europe, where British gardeners adopted goldenrod long before
Americans did as garden subjects. Goldenrod only began to gain some
acceptance in American gardening during the 1980s.
They have become invasive species in other parts of the world, including
China; Solidago canadensis, which was introduced as a garden plant in Central
Europe, has become common in the wild, and in Germany is considered an invasive
species that displaces native vegetation from its natural habitat.
Goldenrod species are used as a food source by the larvae of many Lepidoptera
species. The invading larva may induce the plant to form a bulbous tissue mass
called a gall around it, upon which the larva then feeds. Various parasitoid
wasps find these galls and lay eggs in the larvae, penetrating the bulb with
their ovipositors. Woodpeckers are known to peck open the galls and eat the
insects in the center. = Cultivated species=
Cultivated goldenrods include: S. bicolor, S. caesia, S. canadensis, S.
cutleri, S. riddellii, S. rigida, S. shortii, and S. virgaurea.
A number of cultivars have been selected, including several of hybrid
origin. A putative hybrid with aster, known as ×Solidaster is less unruly,
with pale yellow flowers, equally suitable for dried arrangements.
Molecular and other evidence points to ×Solidaster being a hybrid of Solidago
ptarmicoides and Solidago canadensis, the former now in Solidago, but likely
the "aster" in question. The cultivars 'Goldenmosa' and S. ×
luteus 'Lemore' have gained the Royal Horticultural Society's Award of Garden
Merit. = Industrial use=
Inventor Thomas Edison experimented with goldenrod to produce rubber, which it
contains naturally. Edison created a fertilization and cultivation process to
maximize the rubber content in each plant. His experiments produced a
12-foot-tall plant that yielded as much as 12% rubber. The tires on the Model T
given to him by his friend Henry Ford were made from goldenrod. Like George
Washington Carver, Henry Ford was deeply interested in the regenerative
properties of soil and the potential of alternative crops such as peanuts and
soybeans to produce plastics, paint, fuel and other products. Ford had long
believed that the world would eventually need a substitute for gasoline, and
supported the production of ethanol as an alternative fuel. In 1942, he would
showcase a car with a lightweight plastic body made from soybeans. Ford
and Carver began corresponding via letter in 1934, and their mutual
admiration deepened after George Washington Carver made a visit to
Michigan in 1937. As Douglas Brinkley writes in "Wheels for the World," his
history of Ford, the automaker donated generously to the Tuskegee Institute,
helping finance Carver's experiments, and Carver in turn spent a period of
time helping to oversee crops at the Ford plantation in Ways, Georgia.
By the time World War II began, Ford had made repeated journeys to Tuskegee to
convince George Washington Carver to come to Dearborn and help him develop a
synthetic rubber to help compensate for wartime rubber shortages. Carver arrived
on July 19, 1942, and set up a laboratory in an old water works
building in Dearborn. He and Ford experimented with different crops,
including sweet potatoes and dandelions, eventually devising a way to make the
rubber substitute from goldenrod, a plant weed commercially viable. Carver
died in January 1943, Ford in April 1947, but the relationship between their
two institutions continued to flourish: As recently as the late 1990s, Ford
awarded grants of $4 million over two years to the George Washington Carver
School at Tuskegee. Extensive process development was
conducted during World War II to commercialize goldenrod as a source of
rubber. The rubber is only contained in the leaves, not the stems or blooms.
Typical rubber content of the leaves is 7%. The resulting rubber is of low
molecular weight, resulting in an excessively tacky compound with poor
tensile properties. = Traditional medicine=
Solidago virgaurea is used in a traditional kidney tonic by
practitioners of herbal medicine to counter inflammation and irritation
caused by bacterial infections or kidney stones. Goldenrod has also been used as
part of a tincture to aid in cleansing of the kidney or bladder during a
healing fast, in conjunction with potassium broth and specific juices.
Native Americans chewed the leaves to relieve sore throats and chewed the
roots to relieve toothaches. Cultural significance
The goldenrod is the state flower of the U.S. states of Kentucky and Nebraska.
Goldenrod was recently named the state wildflower of South Carolina. The sweet
goldenrod is the state herb of Delaware. Goldenrod was the state flower of
Alabama, but it was later rejected in favour of the camellia.
In the Midwestern United States, the blooming of goldenrods in August is a
reminder that it will soon be time for children to go back to school after
summer vacation. Diversity
Accepted Species Solidago albopilosa E.L.Braun –
whitehair goldenrod Solidago altiplanities C.E.S. Taylor &
R.J.Taylor – high plains goldenrod Solidago altissima L. – Canada
goldenrod, late goldenrod Solidago amplexicaulis Torr. & A.Gray
Solidago arenicola B.R. Keener & Kral – southern racemose goldenrod
Solidago argentinensis López Laphitz, Rita María & Semple
Solidago arguta Ait. – Atlantic goldenrod, forest goldenrod, toothed
goldenrod, cut-leaf goldenrod Solidago aurea Spreng.
Solidago auriculata Shuttlw. ex Blake – eared goldenrod, clasping goldenrod
Solidago bartramiana Fernald Solidago bicolor L. – white goldenrod,
silverrod Solidago brachyphylla Chapman – Dixie
goldenrod Solidago brendiae Semple
Solidago buckleyi Torr. & Gray – Buckley's goldenrod
Solidago caesia L. – wreath goldenrod, axillary goldenrod, bluestem goldenrod,
woodland goldenrod Solidago calcicola Fernald
Solidago californica Nutt. Solidago canadensis L. : Canada
goldenrod, Canadian goldenrod, common goldenrod
Solidago chilensis Meyen Solidago compacta Turcz.
Solidago confinis A.Gray Solidago coreana H.S.Pak
Solidago curtisii Torr. & A.Gray – mountain decumbent goldenrod, Curtis'
goldenrod Solidago dahurica Kitagawa ex Juzepczuk
Solidago decurrens Loureiro Solidago delicatula Small – elmleaf
goldenrod, smooth elm-leaf goldenrod Solidago drummondii Torr. & A.Gray. –
Drummond's goldenrod Solidago durangensis G.L.Nesom
Solidago elongata Nutt. – West Coast goldenrod, Cascade Canada goldenrod
Solidago erecta Nutt. – showy goldenrod, slender goldenrod
Solidago ericamerioides G.L.Nesom Solidago faucibus Wieboldt – gorge
goldenrod Solidago fistulosa P.Mill. – pine-barren
goldenrod Solidago flexicaulis L. – zigzag
goldenrod, broadleaf goldenrod Solidago gattingeri Chapman –
Gattinger's goldenrod Solidago gigantea Ait. – giant
goldenrod, tall goldenrod, early goldenrod, smooth goldenrod
Solidago glabra Desf. Solidago glomerata Michx. – clustered
goldenrod, skunk goldenrod Solidago guiradonis A.Gray – Guirado's
goldenrod Solidago gypsophila G.L.Nesom
Solidago hintoniorum G.L.Nesom Solidago hispida Muhl. ex Willd. – hairy
goldenrod Solidago houghtonii Torr. & A.Gray ex
A.Gray – Houghton's goldenrod Solidago humilis Mill.
Solidago inornata Lunell Solidago juliae G.L.Nesom – Julia's
goldenrod Solidago juncea Ait. – early goldenrod
Solidago kralii Semple – Kral's goldenrod
Solidago kuhistanica Juz. Solidago kurilensis Juz.
Solidago lancifolia Torr. & A.Gray – lance-leaf goldenrod
Solidago latissimifolia P.Mill. – Elliott's goldenrod
Solidago leavenworthii Torr. & A.Gray – Leavenworth's goldenrod
Solidago leiocarpa DC. in DC. &. A.DC. – Cutler's alpine goldenrod
Solidago lepida DC. – western Canada goldenrod
Solidago ludoviciana Small – Louisiana goldenrod
Solidago macrophylla Pursh – largeleaf goldenrod
Solidago macvaughii G.L.Nesom Solidago microglossa DC.
Solidago minutissima Kitam. Solidago missouriensis Nutt. – Missouri
goldenrod, prairie goldenrod, Tolmie's goldenrod
Solidago mollis Bartl. – velvety goldenrod, soft goldenrod, woolly
goldenrod Solidago multiradiata Ait. – Rocky
Mountain goldenrod, alpine goldenrod, northern goldenrod, manyray goldenrod
Solidago nana Nutt. – baby goldenrod, dwarf goldenrod, gray goldenrod
Solidago nemoralis Ait. – gray goldenrod, dyersweed goldenrod,
old-field goldenrod Solidago nitida Torr. & A.Gray – shiny
goldenrod Solidago odora Ait. – anise-scented
goldenrod, sweet goldenrod, fragrant goldenrod
Solidago ohioensis Riddell – Ohio goldenrod
Solidago orientalis G.L.Nesom Solidago ouachitensis C.E.S.Taylor &
R.J.Taylor – Ouachita Mountains goldenrod
Solidago ovata Friesner Solidago pacifica Juzepczuk
Solidago paniculata DC. Solidago patagonica Phil.
Solidago patula Muhl. ex Willd. – roundleaf goldenrod, roughleaf goldenrod
Solidago petiolaris Ait. – downy ragged goldenrod
Solidago perornata Lunell Solidago pilosa Mill.
Solidago pinetorum Small – Small's goldenrod
Solidago plumosa Small – plumed goldenrod, plumose goldenrod, Yadkin
River goldenrod Solidago pringlei Fernald
Solidago procera Aiton Solidago ptarmicoides B.Boivin – white
flat-top goldenrod, upland white aster Solidago puberula Nutt. – downy
goldenrod Solidago pulchra Small – Carolina
goldenrod Solidago radula Nutt. – western rough
goldenrod Solidago riddellii Frank ex Riddell –
Riddell's goldenrod Solidago rigida L. – rigid goldenrod,
stiff-leaf goldenrod Solidago roanensis Porter – Roan
Mountain goldenrod Solidago rugosa P.Mill. – wrinkleleaf
goldenrod, rough-stemmed goldenrod Solidago rupestris Raf. – rock goldenrod
Solidago satanica Lunell Solidago sciaphila Steele – shadowy
goldenrod Solidago sempervirens L. – seaside
goldenrod, salt-marsh goldenrod Solidago serotina Retz.
Solidago shortii Torr. & A.Gray – Short's goldenrod
Solidago simplex Kunth : Mt. Albert goldenrod, sticky goldenrod
Solidago spathulata DC. – coast goldenrod
Solidago speciosa Nutt. – showy goldenrod, noble goldenrod
Solidago spectabilis A.Gray – Nevada goldenrod, basin goldenrod
Solidago sphacelata Raf. – autumn goldenrod, false goldenrod
Solidago spithamaea M.A.Curtis – Blue Ridge goldenrod, skunk goldenrod
Solidago spiraeifolia Fisch. ex Herder Solidago squarrosa Nutt. – stout
goldenrod Solidago stricta Ait. – wand goldenrod,
willow-leaf goldenrod Solidago tarda Mack. – Atlantic
goldenrod Solidago tortifolia Ell. – twistleaf
goldenrod Solidago uliginosa Nutt. – bog
goldenrod, fall goldenrod Solidago ulmifolia Muhl. ex Willd. –
elmleaf goldenrod Solidago velutina DC. – threenerve
goldenrod, velvety goldenrod Solidago verna M.A.Curtis –
springflowering goldenrod Solidago villosicarpa LeBlond –
glandular wand goldenrod, hairy-seed goldenrod
Solidago virgaurea L. – European goldenrod
Solidago wrightii A.Gray – Wright's goldenrod
Solidago yokusaiana Makino Natural hybrids
Solidago × asperula Desf. Solidago × beaudryi Boivin
Solidago × calcicola Fernald – limestone goldenrod
Solidago × erskinei Boivin Solidago × ovata Friesner
Solidago × ulmicaesia Friesner Formerly included
Numerous species formerly considered members of Solidago are now regarded as
better suited to other genera, including Brintonia, Duhaldea, Euthamia,
Gundlachia, Inula, Jacobaea, Leptostelma, Olearia, Oligoneuron,
Psiadia, Senecio, Sphagneticola, Symphyotrichum, Trixis, Xylothamia
References External links
Goldenrod identification. Andy's Northern Ontario Wildflowers.
Goldenrods Group. Ontario Wildflowers. Solidago: Goldenrods. Astereae Lab.
University of Waterloo.