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    "Solidago" is from the Latin "solidus" meaning "whole" or "solid", referring to the plant's supposed medicinal use for healing injuries. Linnaeus named this genus in 1753. "Goldenrod" is a common name applied to all Solidagos.

    John Semple, Solidago expert and author of the Flora of North America treatment of that genus, makes these general comments about Solidagos on his University of Waterloo "Astereae Lab" web site:

Solidago includes about 133 species world wide: 120 species native to Canada and the United States, 8-9 species native to Mexico, and 10-12 species native to South America, the Azores, Europe and Asia. The latter are derived from North American taxa. All species are herbaceous perennials ranging from 2 cm to 2.5 m tall. These usually have small heads with yellow pistillate ray florets and perfect disc florets aggregated into flat-topped, wand-shaped or secund-conical inflorescences. The phyllaries are generally lanceolate to ovate or oblong, present in 2-4 graduated series, and have a translucent midrib.

    For individual species of Solidago, see Semple's, "Classifications and Illustrations of Goldenrods".

     Two species of Solidago are shown and discussed below. As of 2019, almost all floras call the first species below, Solidago simplex, but John Semple's research shows that Solidago simplex, first discovered for science in Mexico, is a species found only in Mexico. The species found through the southern Rockies (see the map below) is properly called Solidago glutinosa, a species first discovered for science by Thomas Nuttall on the "plains of the Oregon and Wahlamet rivers", in 1833 and named and described by Nuttall in 1841.

    The two species of Solidago shown on this page are similar and floras do not always agree on their distinguishing characteristics. Most floras separate them on the basis of the number of ray flowers, indicating that S. multiradiata has about 13 ray flowers and S. glutinosa about 8. However, other floras, e.g., the Flora of North America indicate that S. multiradiata has 12-18 ray flowers and S. glutinosa has 7-16 ray flowers.

     Some floras indicate that it is the differences in the hairiness of the plants leaves or stems or inflorescence or the shape of the inflorescence that separate the two species.

    There does seem to be agreement that the basal leaf petioles of S. multiradiata have (or almost always have) hairy margins, i.e., they are ciliate margined, whereas those of S. glutinosa are glabrous or minutely ciliate. See below for a photo showing the ciliate margins of S. multiradiata basal leaf petioles.

    The other point of considerable agreement is that the phyllaries of S. multiradiata are "unequal to almost equal" in length, but those of S. glutinosa are "strongly unequal". See photographs below.

    Semple points out that a key characteristic of Solidago glutinosa is its glutinous flower heads.

    There is disagreement about the elevational range of Solidago multiradiata. Weber, says it is found from the foothills to the subalpine; Ackerfield says foothills to alpine; Intermountain Flora and A Utah Flora indicate that S. multiradiata is found from the montane to the alpine; Semple and Nesom in the Flora of the Four Corners Region indicate that the range is subalpine and alpine. Semple in the Flora of North America says Solidago multiradiata is a species of the alpine. Of my photographs below of S. multiradiata, only the first was taken in the alpine. The rest were taken from 10,000' to 10,600".

    There is also some disagreement about the elevational range of S. glutinosa, but it is not as dramatic a difference among floras as the variance in range for S. multiradiata. It is generally agreed that S. glutinosa tends to be at lower elevations than S. multiradiata. Most floras indicate the range of S. glutinosa to be from montane to alpine.

Solidago simplex

Solidago simplex

Solidago simplex

Solidago simplex

Solidago glutinosa.  Synonyms: Solidago simplex, Solidago spathulata. (Sticky Goldenrod)
Asteraceae (Sunflower Family)

Montane, subalpine, alpine. Meadows. Summer.
Above: Lower Calico National Recreation Trail, August 12, 2019 and Wildcat Canyon Trail, August 27, 2007.
Left: Haviland Lake Trail, June 28, 2004.

This Solidago is widespread from Alaska down the Rockies to Mexico to Virginia to Quebec.  It grows from an inch tall in tundra to a foot-and-a-half tall in more hospitable environments.  It is usually shorter than S. multiradiata and has about eight rays per flower head whereas S. multiradiata has about thirteen.  Both have small, clustered, very bright golden yellow flowers giving plants a very soft, fuzzy appearance.

See the discussions at the top of this page and under S. multiradiata.

Solidago simplex was first collected for science by Humboldt, Bonpland, and Kunth near Santa Rosa, Mexico and was named and described by Humboldt in 1820. "Simplex" is Latin for "simple".

Solidago glutinosa was first discovered for science by Thomas Nuttall on the "plains of the Oregon and Wahlamet rivers", in 1833 and named and described by Nuttall in 1841.

Solidago simplex
Solidago glutinosa.  Synonyms: Solidago simplex, Solidago spathulata. (Sticky Goldenrod)
Asteraceae (Sunflower Family)

Montane, subalpine, alpine. Meadows. Summer.
Haviland Lake Trail, July 23, 2005 and Wildcat Canyon Trail, August 27, 2007.

S. glutinosa usually has about 8 ray flowers but can range from 5-11 ray flowers (or even to 16, according to the Flora of North America). Its very similar cousin, S. multiradiata, often has about 13 ray flowers with a range given as 12-18.

The Flora of North America indicates that the "somewhat viscid-resinous heads of Solidago glutinosa are its most distinctive feature".

The phyllaries of S. multiradiata are nearly equal in length, those of S. glutinosa are of very different lengths. Below, I outlined the tips of six phyllaries in red.

                          Solidago simplex                

Solidago simplex
Solidago glutinosa.  Synonyms: Solidago simplex, Solidago spathulata. (Sticky Goldenrod)
Asteraceae (Sunflower Family)

Montane, subalpine, alpine. Meadows. Summer.
Haviland Lake Trail, July 23, 2005.

Solidago simplex
Solidago glutinosa.  Synonyms: Solidago simplex, Solidago spathulata. (Sticky Goldenrod)
Asteraceae (Sunflower Family)

Montane, subalpine, alpine. Meadows. Summer.
Haviland Lake Trail, July 23, 2005.

The very lowest leaves are often toothed on their edges and have distinct petioles (lowest arrow).

As leaves are added upward along the stem, they become smaller, smooth on their edges, and sessile.

Lower leaves are ample and generally spatulate; upper leaves are smaller and narrower.

Leaf tips are sometimes said to be obtuse to rounded, but as is evident from this photograph, they can also be acute.

 

Solidago multiradiata
Solidago multiradiata
Solidago multiradiata (Rocky Mountain Goldenrod)
Asteraceae (Sunflower Family)

Montane, subalpine, alpine. Openings, woodlands. Summer.
Above: El Diente Trail at tree-line, August 19, 2019.
Left: Kilpacker Trail, July 22, 2004.

This is a very common plant of the subalpine and alpine zones.  Because it often grows in small, dense patches and has numerous small flowers, it can give the impression of a very small fuzzy-top shrub.  It grows to over two feet tall, but plants are more commonly about a foot tall.

As discussed above, there is little agreement in floras about how to distinguish this species from the very similar S. glutinosa (shown above), but several characteristics seem to be agreed on:

First, both S. multiradiata and S. glutinosa are distinguished from a number of other Solidagos by their rounded arrangement of flower heads (rather than arched and one-sided, see Solidago velutina). Further,

S. multiradiata can then be separated from S. glutinosa by its distinctly ciliate-margined leaf petioles (vs. no, or very minutely, ciliate margins in S. glutinosa);

by its often more numerous ray flowers (12-18, usually about 13) (vs. 5-16, usually about 8 for S. glutinosa);

by the nearly equal length of its phyllaries (vs. S. glutinosa with "strongly unequal" in "3-4 series" Flora of North America);

by elevation: S. multiradiata is usually not found at the lower levels of the foothills or montane; S. glutinosa is. Some floras indicate S. multiradiata is not found below 8,000', one indicates not below 8,700', one indicates not below 10,600', and the Solidago expert John Semple indicates that S. multiradiata is a species of the alpine. Of my S. multiradiata photographs, only the first was taken in the alpine. The rest were taken from 10,000' to 10,600".

and by stickiness: The Flora of North America indicates, "The somewhat viscid-resinous heads of Solidago glutinosa are its most distinctive feature, separating it from similar sympatric species [i.e., species occurring within the same geographical area]. My experience is that the heads are glutinous, but they may not feel that way. If you look at the phyllaries with a 10x hand lens you will see the sheen of glandular, glutinous drops.

The first specimen of Solidago multiradiata was collected for science in eastern Canada either in 1765 by Moravian missionaries in Labrador or by Joseph Banks in Newfoundland and Labrador in 1766.  Aiton named the plant in 1789. "Multiradiata" refers to the "many ray flowers".

Solidago multiradiata
Solidago multiradiata (Rocky Mountain Goldenrod)
Asteraceae (Sunflower Family)

Montane, subalpine, alpine. Openings, woodlands. Summer.
Colorado Trail above Roaring Fork, July 26, 2004 and
Kilpacker Trail, July 22, 2004.

You can just about count the 13 petals of the ray flowers. The trouble in counting them is that the heads are crowded together and over-lapping and it is common to find heads with some petals of the ray flowers very tiny or inconspicuous because they are just developing and some petals are bent, contorted, or destroyed.

While humans are concerned with such trivia, insects know what really matters.

                           Solidago multiradiata

Solidago multiradiata
Solidago multiradiata (Rocky Mountain Goldenrod)
Asteraceae (Sunflower Family)

Montane, subalpine, alpine. Openings, woodlands. Summer.
Taylor Mesa, August 22, 2019.

Phyllaries are said to be equal, or moderately overlapping, in length, as they are in the photograph at left. However, I have examined some S. multiradiata phyllaries which vary considerably in size in three or four over-lapping rows.

As shown above, phyllaries of S. glutinosa are strongly unequal.

Solidago multiradiata
Solidago multiradiata (Rocky Mountain Goldenrod)
Asteraceae (Sunflower Family)

Montane, subalpine, alpine. Openings, woodlands. Summer.
Taylor Mesa, August 22, 2019.

The photograph at left shows you that getting down on your belly, pulling some basal leaf blades aside, and poking your camera in, gets you a photograph with hairs on the leaf petiole still difficult to see, appearing at  first to be just a very fine saw-tooth edge of the leaf.

Greater magnification and better light show the hairs, still hardly noticeable.

   Solidago multiradiata   


Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Solidago glutinosa

Range map for Solidago glutinosa

Range map for Solidago multiradiata