Astery Things #2: The Joe-Pye Weeds

Eutrochium fistulosum

Once upon a time there was a genus of plants called Eupatorium. It was a large genus, lumping together plants commonly known as thoroughworts, bonesets, mistflowers, snakeroots, and joe-pye weeds. Roughly twenty years ago, the genus was split into twelve or more genera. Thoroughworts and bonesets are still Eupatoriums; mistflowers are now Conoclinium, and snakeroots Ageratina. Joe-pye weeds, those plants with large arrays of pink-purple flowers and whorled leaves, were placed in the new genus Eutrochium.

Eutrochium maculatum

Historically, four of North America’s five Eutrochium species were found in Maryland, but one of them, E. maculatum (spotted joe-pye weed), has been extirpated. The other three are

  • E. dubium (eastern or coastal plain joe-pye weed)
  • E. fistulosum (hollow joe-pye weed, trumpetweed)
  • E. purpureum (sweet, sweet-scented, or purple node joe-pye weed)

Distinguishing these four species from one another is fairly straightforward, provided you can look at mature, flowering specimens. Here is a much abbreviated chart of some identifying characteristics, taken from the Flora of North America, with the most useful ones in bold purple:

  E. dubium E. fistulosum E. maculatum E. purpureum
stems
purple-spotted purple purple spotted dark purple at nodes
  sometimes solid purple sometimes spotted sometimes solid purple greenish to purple-green
  solid hollow solid; may be hollow at base solid; may be hollow at base
leaves
arrangement in whorls of 3-4 in whorls of 4-6(-7) in whorls of (3-)4-5(-6) in whorls of 3-4(-5)
venation 3-nerved pinnately veined pinnately veined pinnately veined
shapes deltate-ovate narrowly lanceolate lance-elliptic lance-ovate
  ovate broadly lanceolate lanceolate ovate
  lance-ovate lance-ovate deltate-ovate
margins coarsely serrate finely serrate sharply or doubly serrate coarsely serrate
bases abruptly contracted gradually tapered gradually tapered gradually tapered
or abruptly tapered or abruptly tapered
florets
number (4-)5-9(-10) (4-)5-7 (8-)9-20(-22) (4-)5-7(-8)
notes
found only in coastal plain over 6 feet tall wide distribution known to hybridize
  and inland along major rivers morphologically variable morphologically variable

When trying to identify plants in the field, remember to look at the totality of characteristics rather than focusing on one or two, because there can be so much variation from plant to plant. And also because you really shouldn’t be cutting into plant stems in the field, at least not in areas where plants are protected.

E. fistulosum: hollow stem

Here are a few pictures to illustrate. Keep in mind that these are garden plants; wild-growing specimens rarely look so lush and full. Also, the E. maculatum pictured in this post is not the species, but rather a cultivar (‘Gateway’). Still, it’s not too far off what a wild plant looks like.

E. fistulosum: a whorl of 4 broadly lanceolate leaves

E. fistulosum: a loose corymb of flower heads

 

 

 

 

 

 

 

 

 

 

 

 

 

 

E. maculatum: whorl of three leaves, purple-spotted stems

 

And here are a few of E. maculatum. It’s worth noting that further up on the stems, the leaves were in whorls of four (but I couldn’t get a good picture up there).

E. maculatum: lanceolate-ovate leaf

 

 

 

 

 

 

 

 

 

Eutrochium species with purple node

This picture from four years ago is probably of E. purpureum, though I was never able to get close enough for a confident ID. At any rate, it shows what a purple node looks like.

 

Of course none of this is what makes joe-pye so interesting. It’s those flowers. Unlike the aster I wrote about in the last post, joe-pyes have no ray florets – only disc florets. Each floret consists of five pointed petals, fused at the base, from which a single long style emerges. The cumulative effect of all those tiny flowers, from 4-24 per head, dozens of heads in each corymbiform inflorescence, up to a dozen inflorescences on each stem, often multiple stems from one plant… it’s just breathtaking.

And then there’s the icing on the cake: joe-pye weeds attract bees and butterflies like crazy.

More about this next time.

 

Astery Things #1: New England Aster

Symphyotrichum novae-angliae is a typical aster, with flower heads consisting of roughly 50 to 75 dark rose to deep purple ray florets ringing a button of 50 to 110 disc florets that are initially yellow but become purple with age.

upper stem leaves

There are quite a few other blue-purple flowering aster species in Maryland, but distinguishing them is a topic for an upcoming post.

flower heads forming

This species is found mostly in New England, of course, and in the upper mid-west and mid-Atlantic, but also ranges south through the Appalachians and into the Great Plains. In scattered areas of the West it’s found as a garden escapee. In Maryland, New England aster is found almost entirely from the Piedmont west, with just a few occurrences in the Coastal Plain.

pruned by rabbits!

The flowers pictured here are typical, but this particular plant is not. Usually New England aster sports one stem (or just a few) standing up to four feel tall; there may be some branching near the top. The plant shown here was pruned several times by rabbits before I got ’round to spraying repellent on it, hence the short, bushy appearance. New England aster grows in a variety of habitats, sunny to partly shady, almost always in moist to wet soils.

 

Clearly it makes a lovely garden plant if you can protect it from herbivory while it’s still small.

 

 

Of Astery Things and Big Butterflies

New York ironweed (Vernonia noveboracensis)

I don’t like putting my blog into summer dormancy, but I haven’t found much in the past month to photograph and write about. But I’ve been itching to start shooting again, so last week, instead of hunting for wildflowers, I decided to spend time photographing flowers a little closer to home – that is, in my own front yard, since a lot of showy native plants are flowering there now. These include both typical and oddball members of the Asteraceae: goldenrod, New York aster, New York ironweed, joe-pye weed, blue mistflower, and the somewhat weedy Carolina elephant’s foot.

Eutrochium maculatum, one of the species commonly called joe-pye weed

Aster family flowers are interesting in many ways, including their ability to attract bees and butterflies. I’ve taken over 700 photos in the past few days; once I’ve finished processing those and doing a bit of research, I’ll finally have more to post about. Stay tuned!

 

 

 

Devastated

the hotspot, 30 July 2015

“Please rain,” I wrote earlier this year. We got rain, alright. This past May was one of the wettest on record. The Capital Weather Gang reported more than 10 inches of rain in a 23 day period. There was a lot of flooding in the Potomac basin.

Not that I was around to witness it; I was traveling. But the clues are still there: deposits of debris, dried mud on the upslope side of the Billy Goat C trail, muddy tree leaves six feet off the ground, that sort of thing. I saw them this morning when I went out to have a look at my favorite bedrock terrace, which I call the hotspot.

the hotspot pond, 10 June 2015; note how lush, with arrowhead in the water

My usual path to it, across a narrow channel, was still underwater, so I went to another low spot and was able to get across via an islet.

The islet was almost empty: only a few plants, maybe a foot tall coming up through the freshly deposited dirt, no more than one plant per square meter. Big piles of woody material, downed trees, shrubs, and vines on the upstream side of boulders and large trees. Lumber. Plastic and glass bottles. A child’s flip-flop shoe.

jimsonweed on the islet, 10 July 2014

I’ve never gone through that area because by this time of year, it’s waist-high or taller in jimson weed.

the hotspot, 30 June 2016, with a bit of the pond in the foreground

The hotspot was almost empty, too. A few nodding onion on the higher rocks. Racemose goldenrod starting to grow. One small clump of big bluestem grass blooming. Remnants of trumpet creeper and poison ivy. A few scraggly shrubs that might be buttonbush. Very little else.

One of the delights of the hotspot is a pond that’s tucked into the rocks, well above the river. The pond supports aquatic plants, and wetland obligates grow next to it. This year, that little pond held more water than I’ve ever seen in it, but nothing green. The rocky edges were crusted in dried mud. No plants.

the hotspot, 18 July 2017; note how low the water in the pond is, but the area is still lush; zoom in to see flowers on buttonbush and milkweed

Last July in that area I saw flowers on buttonbush, wild potato vine, swamp milkweed, Carolina horsenettle, water willow, thin-leaved sunflower, swamp candles, common arrowhead, fogfruit, and nodding onion. Seedpods on wild blue indigo, and buds on Culver’s root. Halberd-leaved rose mallow taller than me and budding up. Same with joe-pye weed. And cardinal flower. And leafcup and cut-leaved coneflower. Honeyvine climbing over everything, not yet blooming. There was a middle-height forb I identified later as Ludwigia decurrens, the first report of this species in Montgomery County.

This year, on the riverbanks near the hotspot the rosemallows are starting to regrow. Leafcup, coneflower, and sunflower are as well, but they’re only about a foot tall. There’s some water willow in the river. I couldn’t find a trace of any of the other plants: no joe-pye weed or wild blue indigo or Culver’s root or cardinal flower. No honeyvine.

I’m devastated. I won’t get to see those nifty flowers this year.

the hotspot and pond, 3 July 2018

The hotspot, however, was not devastated. This sort of flooding is part of the natural rhythm of the Potomac; the river’s occasional scouring of the bedrock terraces is one of the factors that allows unusual plants, and unusual plant communities, to thrive there. I have no doubt that all the species I mentioned above will be back next year (unless it floods again), in all their glory. And maybe the river will have brought something new.

check the archives for July, 2017, for pictures of plants growing in the hotspot: Golden Glow, Bewitched by Buttonbush, Common Arrowhead, and Ribbet

This is Not Giant Hogweed

Rain ends drought. And rain brings mosquitoes. So many mosquitoes.

I was walking on a wet towpath. So many mosquitoes. Their little whining buzzing was continual, and too close to my ears. Their attacks were continual. It was so humid, I sweated off the first coat of Ben’s 100 in 20 minutes, and took to walking with the bottle in hand. I hate putting poison on my skin, I hate strong odors. Why was I doing this?

To find a plant, of course. Recent reports of a giant hogweed (Heracleum mantegazzianum) sighting in northern Virginia has led to a bit of a media frenzy, which reminded me of the walk I took with a friend last April. She had pointed at some very large leaves and asked, “what’s that?”

I didn’t know, but figured it for something in the Apiaceae, so I took a few pictures and looked it up later. Turned out to be cow parsnip, Heracleum maximum, a close relative of the plant everyone’s been fussing about.

So there I was, enduring the mosquitoes. I found the plants, a nice stand of them, but sadly they were done blooming. Also they were largely guarded by walls of stinging nettles, so I’ll admit it: I didn’t even try to get good pictures. I got as close as I reasonably could, got a few shots, and then got the hell out of there.

I really can’t overstate just how thick the mosquitoes were.

At any rate, cow parsnip, which is listed S3/watchlist in Maryland, is easily confused with giant hogweed. There have been a few sightings of the latter in recent years, but I understand that those plants were reported to the authorities, who removed them.

I’d love to be able to post pictures of giant hogweed, but I’ve never seen it. I’ll consider that a good thing.

The principal difference between the two is size, although that doesn’t help early in the season, when plants are still small. Giant hogweed grows to five and a half meters (18 feet!) tall, with a stem diameter of 15 centimeters (six inches). Cow parsnip grows to three meters (ten feet), with a stem diameter of five centimeters (two inches). The leaves and umbels are correspondingly sized (much larger on giant hogweed). The largest cow parsnip plants pictured above were about seven feet tall.

A more useful way of telling them apart is to look at the lowest leaves. Both species have compound leaves. Cow parsnip leaves generally have three rather broad lobes, while giant hogweed’s are much narrower and often irregular.

Also, the stems are different. Here’s cow parsnip; notice that but for the hairs, it’s solidly green. Giant hogweed stems have purple splotches. Both species have that ring of hairs at the nodes.

I wrote about the poisonous aspects of these plants in this post.

Remember, plants in the parsley family look a lot alike to the untrained eye. I’ve seen people mistake poison hemlock for Queen Anne’s lace, for example. Some umbellifers are tasty; others are deadly poisonous. Don’t mess around with them.

ps – about one hour after scheduling this piece to post, I saw this:

Dear Friends –
Maryland Native Plant Society board members
Jil Swearingen and (possibly) Rod Simmons will be on the Kojo Nnamdi Show on WAMU between 12:30 and 1:00 on Tuesday June 26. The topic is invasive plants. It was inspired by recent reports of giant hogweed in Virginia.

Be sure to tune in!

https://wamu.org/show/the-kojo-nnamdi-show

(Jil is one of the founding directors of MNPS and Rod is a Past President.)

Like a Marble, or an Eye

More small blue things from May. Between travel and rain I haven’t had the opportunity to go hunting in Maryland for several weeks now.

This annual is truly one of my favorites, and I make a point of hunting for it every year. Venus’ looking glass (Triodanis perfoliata) likes poor soils; look for it in open rocky or sandy places.

 

 

I have been having so much fun shooting with The Beast (70-200mm lens). Just look at the sparkle on those petals!

 

 

 

This is a species of Sisyrinchium, probably S. angustifolium though I can’t be sure. Blue-eyed grass is the common name, and indeed the leaves are grass-like. It’s in the iris family.

 

And speaking of irises, the ones I obsessed over last year are going strong. The ones along the canal are, anyway. The ones in the vernal pool are growing like crazy but I haven’t seen flowers on them yet.

I wish I had some new pictures of Baptisia australis to share, but honestly I haven’t even been out to shoot them. We’ve had tremendous amounts of (badly needed) rain in recent weeks, and I know that part of the river well enough to know that one stand is under water. Here’s what they looked like budding up in early May this year.


The other stand I’m sure is fine, but the channel I need to cross to get at them is flooded, too. Here’s a picture from last year.

Today I Am…

Random pictures of small blue things (and purple things), because once again I haven’t the time to write meaningful content.

I don’t know if this is a color variation of common blue violet (Viola sororia) or something else. There is a well-known white form, sometimes called Confederate violet, but it doesn’t look quite like this one. Violets are notoriously promiscuous so who knows. The color is remarkably consistent every year. I’ve only seen them at Rachel Carson Conservation Park.

If you see a blue violet that stands well above the level of its leaves, and if it’s growing in or very near to open water, then it’s probably marsh blue violet (Viola cucullata).

 

 

Wild geranium (Geranium maculatum), also at RCCP. These two were somewhat bluer than is typical.

 

 

 

Virginia spiderwort (Tradescantia virginiana) There aren’t many three-petaled flowers around.

 

 

 


Only one of the seven species of Oxalis found in Maryland is an alien, but some of the others can be awfully weedy. I like them anyway. I’ve been on the hunt for Oxalis colorea, previously overlooked here until a fellow botanerd found it [hi, Bill]. If I make any progress I’ll write about it. In the meantime, though, you just can’t call violet woodsorrel (Oxalis violacea) a weed.

Even the leaves are charming.