Weakley Flora to the Rescue! (With a Primer on Using Botanical Keys)

upper stpem, leaves, and inflorescence

upper stem, leaves, and inflorescence

The day after writing the previous post, I returned to Serpentine Barrens Conservation Park armed with a 10X lens, a small knife, a ruler, a notebook, and most important, a printout of page 1126 of the Flora of the Southern and Mid-Atlantic States by Alan S. Weakley, determined to key out my unknown goldenrod species.

Success! I keyed it out in the field, but collected a sample to photograph at home with the macro lens.

If you’re interested in how botanical keys work, keep reading. If you just want to know which species it is, skip to the end.

The first couplet in Weakley’s key reads:

1  Leaves with numerous slightly raised, pale, translucent, blister-like pustules; leaves transmit light when held up; plant glabrous………E. leptocephala
1  Leaves without pale pustules, or if present then leaves opaque and do not transmit light; plants glabrate to pubescent.

Glabrous is smooth, glabrate means “almost smooth”, and a pubescent area is covered in short hairs.

closeup of stem and leaf base showing hairs

closeup of stem and leaf base showing hairs

 

Have a look at this photo. Clearly the plant is hairy, so I chose the second line, which leads to this couplet:

 

 

 

2  Major veins on leaf underside 3-5 (if 3 then all 3 veins bold), leaves 5-12 mm wide; heads with 20-50 flowers.
2  Major veins on leaf underside 1-3 (-5) (if 3 or 5 then only the midvein bold), leaves <6 mm wide (-8 mm wide in E. gymnospermoides); heads with 10-20 flowers.

leaf base, underside

underside of leaf at base

In the field I measured the largest leaves that were still intact on the plant. (All the lower, presumably largest, leaves had turned brown and curled up and many had fallen off.) Most of them were in the 7-8 mm range. Every leaf I examined had five veins, though some were pretty hard to see. Given these facts, I chose the first line of couplet 2 (more about the flower heads later), which leads to

3  Leaves 3-6 (-8) mm wide, punctae on leaf upperside bold, flower heads 10-20 flowered………..E. gymnospermoides
3  Leaves 5-12 mm wide, punctae on leaf upperside obscure or not bold, flower heads 20-50 flowered.

Again based on leaf width, and the fact that the punctae (dots) were not bold, I chose the second line, which leads to

4  Leaf undersides, upper stems, and branches glabrate, often with villous hairs on midrib of leaf underside …………………E. graminifolia var. graminifolia 
4 Leaf undersides, upper stems, and branches copiously to moderately short villous
…. E. graminifolia var. nuttallii

Look at the first picture again; I’d call that copiously villous. (“Villous” means covered in soft hairs.)

flower heads (7/32" long)

flower heads (7/32″ long)

About the flowers… Remember that plants in the Asteraceae have composite flowers. That little thing next to the ruler in this picture, measuring only about five and a half millimeters long, is a flower head – a collection of flowers. At least, it was, as these had all turned to seed. I was able to cut some open and tease out the seeds. I didn’t count more than 20 in any single head, which suggests about 20 flowers (each flower produces one seed). But, they were minute, and I was working with a small knife and a 10X hand lens, so it’s quite likely my count was inaccurate. Since I couldn’t get a true count of flowers per head, I ignored that part of the key.

seeds

seeds

So there it is. My mystery grass-leaved goldenrod/goldentop is Euthamia graminifolia var. nuttallii.

The More I Learn, the Less I Know

Readers of this blog will have noticed that I am fascinated by names. It isn’t enough for me to spot a plant and say “that’s a goldenrod”; I need to know which goldenrod, the actual species name, what other common names there might be for it and what the Latin words translate to and how it relates to other species… and pretty much anything else related to its taxonomy.

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No plant has led me into taxonomic Wonderland like this one —>.
I first saw it at Serpentine Barrens Conservation Park, in late August in bud, then in October in flower (kind of).

Right away I recognized it for a goldenrod, yet it looked a little different from other goldenrods. The flower heads weren’t in plumes or in the leaf axils like other goldenrods I know. So I took a few pictures, went home, and opened the books. It was easily categorized into “flat-topped goldenrods”, sometimes known as goldentops, for which Newcomb lists two Solidago species and Peterson lists four; Clemants and Gracie list two Euthamia species and two Oligoneuron species.

Hmm. Time to open more books.

Melanie Choukas-Bradley, in An Illustrated Guide to Eastern Woodland Wildflowers and Trees (2004), describes a lance-leaved goldenrod, Solidago graminifolia, noting that it’s also called Euthamia graminifolia, and also noting that “some botanists…consign the flat-topped goldenrods to a separate genus (Euthamia).”

Fleming, Lobstein, and Tufty, in Finding Wildflowers in the Washington-Baltimore Area (1995), report seeing “lance-leaved goldenrod (Solidago graminifolia)” in the area where I found this plant (they call the area the Potomac Power Line).

At this point I had tentatively decided that what I found and photographed would currently be called Euthamia graminifolia. I decided to run it by a few experts for confirmation. That’s when I learned that Euthamia is a “problem genus”.

Now I was really interested in learning what was going on, so I consulted a bunch of internet sources, and that’s when things got a little crazy.

In short, the USDA PLANTS Database lists six Euthamia species, not all of which are found in the Maryland Piedmont. BONAP lists five, only one of which is in the Piedmont. MBP lists four, only one of which is in the Piedmont. ITIS recognizes four species, and lists thirty-six Latin synonyms for E. graminifolia. Thirty-six!

Now totally confused, I consulted even more authorities, and found the following:

from EOL

 Euthamia is a genus of flowering plants in the aster family, Asteraceae.[2][3] They are known commonly as goldentops[4] and grass-leaved goldenrods.[5][6]

The species were formerly classed in genus Solidago, the goldenrods. They were separated on the basis of morphological differences, such as the arrangement of the flower heads in the inflorescence and the glands on the leaves, and of DNA data.[7] Authors have recognized 5 to 10 species.[5]

from the Astereae Lab:

Euthamia… is a small genus of erect, herbaceous perennials native to North America. Sierren (1981) revised the genus and recognized nine eastern species and one western species. Haines (2006 Flora North America) recognized only five species. Euthamia was incorrectly included in Solidago by many authors for a more than a century. Cronquist (1981) accepted the distinct generic status for this group of species on the basis of morphology and leaf anatomy (Anderson and Creech 1975).

Lane et al. (1996) showed that the on the bases of cpDNA, Euthamia was phylogenetically not close to the true goldenrods with a number of other genera more closely related…

Unfortunately, the practice of placing the grass-leaved goldenrods in Solidago continues and leads to errors in interpreting the results of ecological studies.

 

And finally, Flora of the Southern and Mid-Atlantic States (Alan S. Weakley, 2015) lists six species, with the note that Euthamia is

A genus of about 8-10 species, herbs, of North America. There are a number of serious problems remaining in our knowledge of Euthamia.

Apparently so.

Weakley’s key is excellent, and if I can get back to the park before the plant is done blooming, I might be able to key it out. Stay tuned…

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on-line sources

USDA PLANTS Database
BONAP (The Biota of North America Program)
MBP (Maryland Biodiversity Project)
ITIS (Integrated Taxonomic Information System)
EOL (Encyclopedia of Life)
Astereae Lab (University of Waterloo)
Weakley Flora (The University of North Carolina Herbarium)

Poor Joe Buttonweed

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poorjoe, rough buttonweed
Diodella teres
(formerly Diodia teres)
Rubiaceae

 

! was really happy to find a member of the Rubiaceae growing in Serpentine Barrens Conservation Park, and even happier to realize it’s a “new-to-me” species. And then I was surprised to learn that it’s considered a nuisance weed of turfgrass. Type “poorjoe” into Google and it will autocomplete to the phrase “poorjoe weed”, and then you’ll find tips on how to eradicate it.

Poorjoe likes disturbed sites and nutrient-poor soils, like in the clear-cut area under power lines where I found these. It’s an annual plant that might sprawl a bit, but is more likely to have ascending stems. The flowers are typically lavender-colored, but there’s some variation and, like a few of the Houstonia species I’ve written about, can appear to be white (or actually be white). They’re borne in the leaf axils. The leaves are sessile, with stipules that form little cups that contain a few long bristles. The stem is often reddish-brown.

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As nuisance madders go, this one isn’t nearly as bad as its cousin Virginia buttonweed (Diodia virginiana). Google that common name, and the whole first page of results will be how to control (kill) it in lawns. Virginia buttonweed is a perennial, sprawling rather than ascending, with white flowers, and no bristles in the leaf axils.

Diodella teres ranges from southern New England south through Florida and west through central Texas, with a few occurrences in the desert Southwest as well. In Maryland it can be found in the Piedmont and parts of the Coastal Plain.

What constitutes a “weed”, anyway? I like this definition: “a plant growing where it isn’t wanted”. I saw only a few poorjoe plants in an area full of invasive aliens, so I’d hardly name it a weed in that context.

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Got Milkwort?

And now back to my finds in Serpentine Barrens Conservation Park.

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purple milkwort, field milkwort
Polygala sanguinea
Polygalaceae

This intriguing small annual grows in moist to dry soils in sunny or partly shady sites. It’s often unbranched, with slender leaves and a tight raceme of flowers that is so dense it appears at first to be a single flower.

In Maryland purple milkwort is found in parts of the Coastal Plain, Piedmont, and Appalachian Plateau. It’s also fairly widespread in eastern North America, occurring in Quebec and Ontario, New England, the mid-Atlantic, the midwest, some parts of the deep South, and into the eastern parts of the Great Plains. There are no conservation issues.

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There are about three dozen species of Polygala in various parts of the US, most with rather limited ranges.  P. sanguinea is one of the most widespread. Thirteen of these species are in Maryland, most of them in the coastal plain.

The genus name Polygala is from two Greek words meaning “many” and “milk” – there was a belief that cows grazing on pasture with Polygala species would produce more milk. Probably that’s the reason for the common name “milkwort”, too. (“Wort” is a Middle English word meaning “plant”.) The specific epithet sanguinea is a reference to blood, but I’m not sure why; possibly because of the color of the flowers?

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My Year of the Gentians (part 1)

Earlier this year I was thrilled to spot my first gentian family species, pennywort (Obolaria virginica), at Rachel Carson Conservation Park. Then last week, I found three more gentian family species, one at Serpentine Barrens Conservation Park, and the other two in Colorado. More on those in the next two posts.

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rosepink, bitterbloom,
rose gentian,
American centaury
Sabatia angularis
Gentianaceae

 

Of the nineteen or so species of Sabatia native to the US, five can be found in Maryland. Of those five, only this one is widespread across the state; the other four are mostly limited to the coastal plain. Two of those are listed as S1/endangered.

Rosepink is a biennial, growing a basal rosette of leaves in its first year and sending up a flowering stalk in its second. The plant reaches to a height of about two and a half feet, with flowers up to an inch and a half across open from July through September. Look for rosepink in meadows and woodland clearings with moist to dry, acidic soils. The two specimens I found were sheltering under the outermost edges of an eastern redcedar (Juniperus virginiana) in a power line right-of-way.

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This species ranges from Ontario south into northern Florida, east to New York (with some occurrences in Massachusetts and Connecticut), and southwest into eastern Texas and Oklahoma. It’s threatened in Michigan and endangered in New York.

 

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Common Dittany

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aka American dittany, Maryland dittany,
frost mint, stone mint, sweet horsemint,
fairy skirts
Cunila origanoides
Lamiaceae

Like the blue curls in my last post, common dittany is in the mint family. It has the characteristic square stems and paired leaves, not to mention a marked fragrance like oregano or thyme, but the flowers are a little atypical. They lack “lips”, and have two stamens rather than four. The flowers are found in terminal clusters and in axillary clusters on the upper portions of the stems.

This species is a perennial subshrub that grows to about one foot tall, with branches often sprawling or flopped over. I came across a single specimen in the Serpentine Barrens Conservation Park, growing in textbook common dittany habitat: dry soil, shade from trees overhead, and little to no competition from other plants on the forest floor.

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There are about a dozen species of Cunila. All except this one are native to South America and southern North America (as far north as Mexico). C. origanoides‘ range includes an area somewhat to the east and west of the Appalachians, from southern New York through South Carolina, and the Ozarks, with a few scattered occurrences elsewhere.

The plant probably got its common moniker “dittany” from a similar looking old-world herb, dittany of Crete (Origanum dictamnus). The specific epithet origanoides means “like oregano”. Native Americans made a tea of common dittany for a variety of medicinal purposes, but please note that it does not have FDA “generally recognized as safe” status (according to The Herb Society of America).

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Blue Curls

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aka forked bluecurls,
bastard pennyroyal
Trichostema dichotomum
Lamiaceae

This mint family member will get your attention. The flower has five petals, two up and three down. But the speckled middle lower petal extends far out from the others, and the four stamens protrude and curl dramatically. The plant itself shows the usual mint family characteristics of paired leaves on a square stem.

Trichostema is from the Greek and means “hair-like stamens”, while dichotomum refers to the way the plant grows (forking in pairs, typical of the Lamiaceae).

Blue curls is a short (to 18 inches) annual plant of dry, sunny places, such as the power line clear-cut in Serpentine Barrens Conservation Park where I found dozens of specimens. They were growing in a swath of orangegrass plants, another species I only just learned about.

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According to various sources, blue curls blooms from August through October. I don’t know if that’s the case in the Maryland Piedmont, but I’ll keep an eye open for them when I go back to that area.

This is one of twelve species of Trichostema native to North America; only two others can be found in this area, and both are on the Maryland DNR’s RTE (rare/threatened/endangered) list. T. dichotomum ranges from Quebec and Ontario south to Florida, Texas to the southwest, and Iowa to the northwest. It’s rare in Indiana and threatened in Michigan. In Maryland look for it in the Piedmont as well as parts of the coastal plain, the Blue Ridge, and the ridge and valley provinces.

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