Flora and fauna of the Athens County area, and occasionally habitats outside Ohio. Subject matter will consist of both interpretive material and taxonomic issues in plant and animal identification.

Thursday, January 19, 2012

Some Ohio Goldenrods

I tried Asters, why not try Goldenrods. Our bright yellow flowers of fields and forests dominate the landscape in late summer and fall. They provide nectar and pollen late in the season for a vast array of insects, especially bees. Depending on whether you are a lumper or splitter, there are about 22 species of Goldenrods in Ohio. The hay fever culprit is Ragweed, but Goldenrods still get much of the blame. Goldenrod pollen is too heavy to be carried by the wind, and is not the cause of your sneezing.

Many people initially separate the Goldenrods by whether or not they have small compact flower heads, or widely branching flowers like these above. I don't start that way, but prefer to use habitat. Rather than open fields, we'll look at the Goldenrods that tend to occupy forest areas first.

Like Asters, you need to look at all parts of the plant. Are the flowers concentrated at the top of the plant, or maybe spread along the entire stem? Do the flowers look compact or crowded together, or reaching out in a secund form like these.

Are the leaves all the same size, or do they change shape and size on various parts of the plant?

Finally, are the stems smooth or hairy?

A very common and easy species to identify is the Flat-topped Goldenrod, Euthamia graminifolia. Not considered a Solidago like most other Goldenrods, it is closely related. The flowers are found strictly at the top of the plant. The leaves are long and narrow, and is sometimes called Grass-leaved Goldenrod. Look for it on forest edges as well as open fields.

While this plant can be found in fields, I tend to see it more in dry open woods. It is the Slender Goldenrod Solidago erecta. This is one of those Goldenrods I call wand like or club like. The flowers hug the twig up and down the stem and never spread outward. The stems are smooth, and the leaves are widely scattered along the main stem. The flowers tend to be a more pale yellow rather than a deep yellow.

Another wand like species found deep in dry woods is the Silver-rod, Solidago bicolor. It blooms later than most species. The stems are hairy, but the real key to identification is the color. This is the one white  goldenrod. Older flowers will fade, while others begin to peak, showing two forms, which is what the word bicolor means.

Moving into moister woods, this very showy Goldenrod will attract your attention even from a distance. Notice how the flowers will bloom from top to the bottom of the stem.

It will grow erect when in the woods, and sideways when along a forest edge. This is the Blue-stemmed Goldenrod, Solidago caesia.

The flowers will grow upward, regardless of which direction the stem points. The leaves will grow straight out from the plant, or droop downward. They rarely grow or point upward.

The hairless stems are red, often with a purple-blue tinge.

As we hike further into moist or wet woods, we come across this sharp toothed, broad leaved species known as Zig-Zag Goldenrod, Solidago flexicaulis.

Up close this flower reminds me of the Lysimachia plant Swamp Candles.

Zig-Zag Goldenrod is so named because of the crooked stem growth. This is a very shade tolerant species.

A Goldenrod next to railroad tracks, what's unusual about that?  Sometimes nothing, but this is a prairie species I found outside of Marion Ohio. There are remnant prairies in this region, and this is the Stiff Goldenrod, Oligoneuron rigidum. Like a few other prairie species, they have been placed in a different genus.

Besides the habitat, Stiff Goldenrod is recognized by the compact flower heads that do not radiate out.

Looking up close, this species has short round leaves covered in dense white hairs. The stem will have these same white hairs. Similar flowering prairie species such as Riddell's and Ohio Goldenrod have longer skinnier leaves. The leafhopper here was being bashful.

Now we start getting into the open area species with wide spreading flower heads. This is Rough-leaf Goldenrod, Solidago patula. Before starting to think these are the ones that all look alike, remember, this one is found in wetlands, and is often called Swamp Goldenrod.

The stem on this is angled, not round. The middle and upper leaves are serrate and have no stem (sessile). They are light green. The lower leaves will be round to egg shaped and form a long winged petiole.

Speaking of wide spreading species, this profile is so typical of many goldenrods. Larger plants of this one may have many spreading plumes. You have to check the leaves.

Smaller plants may have only a single panicle of flowers. So what is this diverse looking species? It's called Wrinkle-leaved Goldenrod, Solidago rugosa. These are found in open fields with rather wet soils.

Separating Wrinkle-leaved from Rough-leaf in a wetland is easy. The leaves are short and the stem is covered in dense hairs. The leaf veins are very prominent.

The leaf veins are so deeply impressed, it gives the surface the appearance of wrinkled skin. The leaves feel raised, as if covered in little bubbles.

Moving to drier habitats, this is a common species of poor soils. The Gray Goldenrod, Solidao nemoralis. Gray Goldenrod is one of the smaller species reaching only 1-3 feet.

Key features include the leaves and stem being covered with very fine hairs. This often gives the plant a grayish-blue look. Leaves are widest near the tip and taper down at the base. On most plants I've seen, the leaves also get smaller as you go up the plant. Gray also has a habit of sending out little leafy shoots between the main leaves. Some say they also recognize it by how the top of the flower head doesn't stay erect, but bends over slightly.

Okay NOW you can say these are the ones that all look the same. These species of open fields with wide spreading plumes are tough.

First thing to do is look at the leaf veins. Several species will show 3 distinct veins in the majority of the leaves. Using the leaf veins, and the hairy stem, the flowering picture above is Canada Goldenrod, Solidago canadensis.

Another clue is this insect created bunch gall. They are almost exclusively on this species. Canada Goldenrod is one of the most common species in our area. Some authors split the Tall Goldenrod, while many others lump Solidago altissima as just a variety of Canada. I have found nothing consistent that separates them.

Another common 3-veined species is the Giant or Late Goldenrod, Solidago gigantea. This plant can reach 7 foot in height. All of these wide plumed goldenrods will show hair on the stem up at the flower heads. You have to look further down to see if the stem stays hairy or not.

The determining factor on Giant Goldenrod is the smooth stem. The stem will turn from green to red-purple. It will often have a white glaucous coating as well. The leaves are smooth and sharply serrate.

Looking at just the flowers won't help on these. Look at the leaf veins, notice they are 1-veined only. This makes it either Early or Sweet Goldenrod.

Those two species are similar. On Early Goldenrod, Solidago juncea, look for stipule like baby leaves growing among the larger leaves. During the flowering period, look at the bottom of the plant. It should have very long leaves and a basal rosette that persist during blooming. Early Goldenrod is so named because it blooms before the others. Don't let the name fool you though, It will continue to flower well into the summer.

If it's Sweet Goldenrod Solidago odora, the lower leaves will have shriveled up and turned brown, or disappeared completely. Of course there is one easier way to tell. If you crush the leaves and get a pleasant anise or licorice odor, you have Sweet Goldenrod.

Well that's only half the species in the state. Perhaps I can find many of the others next year. Of course being in the field with an expert might help!


  1. Hi Dennis. Way to take on the goldenrods! Do you see Euthamia leptocephala in Ohio? None of the range maps I've seen show it closer to Ohio than the intersection of Missouri, Illinois, and Kentucky. You say that it's common... I wonder if you're thinking of E. graminifolia.

    If you haven't already seen it, there is a guide to common goldenrods of the Chicago Region at http://fm2.fieldmuseum.org/plantguides/guide_pdfs/Solidago%20Rapid%20Color%20Guide-CW9.pdf. Although we don't get the southern influence that you would have in southern Ohio, many of the species found here are also found there.

  2. For some reason, that link isn't working... you'll have to type it into your browser to see the goldenrod guide...

  3. My bad Scott, I meant graminifolia all along. Got the PDF of that publication. Nice to see they illustrate many of the same specifics I mentioned. I feel good about that.

  4. Your descriptions of goldenrods really make me wonder just what I have in my backyard. I had pretty much decided it was solidago odora except that my husband and I have crushed many leaves and find no hint of anise. But nothing else that I have found really describes this plant. While I have a plant in my backyard, it is everywhere on the roadsides here in southeast Michigan near Lake Erie and just beginning to bloom (September 12). One of the plants in my yard is already 6 ft. tall. The flowers are plumes not resembling Riddell's domed cluster. The stem is smooth. The leaves are smooth, top and bottom. I cannot see any teeth even with a magnifying glass but the edge feels just slightly rough. The leaves show a central vein that you can fold the leaf on, similar to Riddell's but not as prominent a feature. There are also minor parallel veins somewhat like the leaves on grass-leaved goldenrod though the parallel veins are more prominent on the grass leaved. Last but most importantly, the flower is really beautiful. I would just like to know what it is :).

    Thanks for sharing your vast knowledge of biology and ecolodgy!

  5. Could you help with this one? How can you differentiate between Solidago odora and Euthamia graminifolia? I crushed a leaf and it smells strongly but not sure that I am smelling anise! Thanks!

  6. Where do you live? I have never seen solidago odora AFAIK. What is ubiquitous here in southeast Michigan appears to be seaside goldenrod, solidago sempervirens. I know, we are very far from the sea but in the winter our roads are salted to melt ice. Lots of salt! I happened upon a reference somewhere that mentioned large populations of seaside goldenrod were introduced near the Detroit River, Southwestern Ontario, Southeast Michigan, and parts of Ohio. If the leaves don't smell of anise, seaside goldenrod may be what you have. It is absolutely ubiquitous on roadsides here in Trenton which is on the Detroit River. It is blooming right now and very beautiful. It is much taller (6 ft.) than Grass-leaved goldenrod, euthamia graminifolia which I have never seen more than 3 ft. tall and which is also blooming right now. The grass-leaved goldenrod has smaller, narrower leaves with a blueish tint and a bushier habitat. Having said all that I need to mention that I am a mere novice identifying goldenrods so take my comments with a grain of seaside salt :).