Astery Things #6: Verbesinas

Lining the highways this time of year are lots of tall white-flowering and yellow-flowering forbs. Various species of goldenrod are among the latter, and so are two other members of the Asteraceae: wingstem and yellow crownbeard, the only species of Verbesina present in Maryland (probably).

At first glance (or at 60 miles per hour), the two look a lot alike. Each can get quite tall, up to two meters, and each has large leaves, thick-looking stems, and dense arrays of composite flowers.

But it’s easy to distinguish between them. Have a look at the similarities and differences. [In the following pairs of photos, V. alternifolia (wingstem) is on the left, and V. occidentalis (yellow crownbeard) is on the right.]

Overall form: tall plants, multi-branched, with thick stems, topped with yellow flowers.

Both have leaf-like tissue running along the stems (hence “wingstem”).

Here’s the most obvious difference: V. alternifolia leaves are mostly alternate along the stems, while the leaves of V. occidentalis are mostly in pairs along the stems.

Note my frequent use of the word “mostly”. There is a lot of morphological variation in these species. In general – and this applies to Symphyotrichum, Helianthus and many other aster family species as well – the leaves tend to get smaller as they ascend the stem, and they start to alternate at the top. You need to consider the entire plant – observe the leaf arrangement at every node, especially lower on the plant – in order to decide what the overall arrangement is.

Speaking of morphological variation, have a look at this. The flowers say wingstem, but how about those whorled leaves? I’m not sure what to think. This one plant was found in an area where both species were growing. Could it be a hybrid?

Now look at the flowers. V. alternifolia often has fewer heads per array than V. occidentalis. However, this should not be considered an identifying characteristic, especially since it’s hard to define exactly what constitutes an array. And, V. alternifolia might have a larger number of arrays (instead of the single one pictured here).

Look at the individual heads. V. alternifolia has more ray florets, generally about six; V. occidentalis has one to three. Also, it seems to me that the rays of V. alternifolia are straight and often reflexed, but the rays of V. occidentalis are somewhat twisted and stick straight out.

These two species grow in the same habitats. I find them on moist soils at the margins of the woods, the river, the canal, and roadways. If you want to get a really good look at them side by side, take a trip to the C&O Canal Lock 6 parking lot on the Clara Barton Parkway. Right between the lawn and the trees, you can find both. You can also find two other closely related astery things, but that’s the subject of my next post.

Now, about my claim that these are the only two Verbesina species present in Maryland… BONAP and USDA PLANTS both show two other species present, but neither source gives county-level data. Look at the BONAP map for V. virginica.  It doesn’t look like this species would be present here in Maryland, does it? If it is, it’s on the lower Eastern Shore. The Maryland Biodiversity Project has no records for it, though, and classifies the other species (V. encelioides) a waif, with only four records, all in Baltimore city. 


ps the top photo shows wingstem blooming above the Potomac River near Great Falls.

Astery Things #5: Carolina Elephant’s-Foot

When an unknown plant appears in my garden, I’ll watch it grow for a season before deciding if it’s a weed.

What is a weed, anyway? My favorite definition is “a plant growing where it isn’t wanted”.

Despite this practical concept, I’ve had a hard time deciding if the Elephantopus carolinianus that appeared as a volunteer in my garden deserves weed status. It’s an interesting plant that stands about a foot and a half tall, with thick but sparse leaves that result in an open, somewhat coarse texture, and it has appealingly unusual flowers. However, it’s deep-rooted and seeds itself freely, which means high weed potential.

Unlike the other species in this series of posts, whose flower heads contain only disk florets, Carolina elephant’s-foot consists only of ray florets. You have to look very closely to see it, but each flower head contains from one to five individual flowers (usually four); each one of those flowers has a single petal that’s so deeply lobed, it appears to be five separate petals.

Look for E. carolinianus in dry soils in sunny or partly sunny areas, for example near rock outcroppings in a woodland, or in disturbed, open areas. It ranges from southern Pennsylvania (where it’s endangered) to eastern Texas. Three other species of Elephantopus are native to the US, all with smaller ranges centered on the southern states.

Astery Things #4: Blue Mistflower

Next in the series of posts on composite flowers lacking ray florets is blue mistflower. Like the joe-pye weeds, blue mistflower was once placed in the genus Eupatorium, but nowadays it’s known as Conoclinium coelestinum. The flowers are somewhat similar in appearance to joe-pyes, the heads of tightly clustered disk florets with long protruding styles giving the inflorescences a fine, feathery, misty look.

click on this one to zoom in and see the minute flowers opening on the outside of the heads

Also like joe-pye weeds, blue mistflower likes wet soils; along the banks of the Potomac River, if I see joe-pyes, I’m almost certain to find blue mistflower nearby. Unlike joe-pyes, the plants are short, getting to about two feet tall in ideal conditions.

Speaking of the Potomac, I went back out to check on the spot I reported on last week, a place where in other years I would definitely find mistflower. It was all underwater again. Lots of rain upstream.

Blue mistflower ranges mostly along the Mississippi River basin and its tributaries, from southern Illinois south, and also in the eastern mid-Atlantic and the Carolinas. It’s found in most of Maryland except for the westernmost and easternmost parts of the state.

eastern tailed-blue butterfly (Cupido comyntas) sipping from mistflower

Apparently these flowers are a great nectar source for a variety of butterflies, but I haven’t seen many on it. Three years ago I wrote that I was worried that the blue mistflowers in my garden would become weedy*. “Weedy” is, of course, in the eye of the gardener. They certainly have spread, somewhat aggressively, and I’ve had to pull some out, but they haven’t reached weed status yet.


*Lepidopterans Photobomb My Mistflower Shoot

Big Butterflies #3: Zebra Swallowtail

While shooting eastern tiger swallowtails in the joe-pye weeds, out of the corner of my eye I kept seeing something large and white darting about in the New York ironweed. I only managed to get a few blurry pictures of it before it disappeared altogether. There’s no doubt what it was: a zebra swallowtail (Protographium marcellus, formerly Eurytides marcellus).

The next day I was outside tending to something else when I saw it again. This time I dashed inside, got the camera, and dashed back outside to the low fence that separates my property from the road. Along this fence I’ve planted understory trees and shrubs, and a few perennials. Among these are two small pawpaws, and that’s where the zebra swallowtail was.

For half an hour I observed its behavior. It would flutter about the pawpaws, settling for maybe a second or two at a time, then it would head south and check out the joe-pyes and ironweeds, then it would make a big loop up the street and come back over the fence on the north side of the yard, gliding back through the trees and shrubs to flutter about the pawpaws again. Sometimes it made a big loop through my yard instead; always it returned to the pawpaws.

The males are known to patrol around pawpaws, looking for females. Pawpaws (Asimina triloba) are the host plant for the caterpillars. Adult zebra swallowtails feed on nectar from a variety of plants, including dogbane, common milkweed, verbena, redbud, and blueberry. I need to plant some of those by next spring, because I sure would like to see more of these striking insects flying about my yard.

Zebra swallowtails are found primarily in the South, southern mid-Atlantic, and southern mid-West. In Maryland, which is almost as far north as they go, they fly in April and August; further south they fly from March to December.

Apparently it’s difficult to distinguish the females from the males, at least when they’re on the wing, other than by observing behavior. The one pictured in this post might be a male; all the time I observed it, I never saw it laying eggs (the females lay one egg at a time, on the undersides of pawpaw leaves). I also haven’t seen any eggs or caterpillars on the plants, though I’ve been checking every day.

Zebra swallowtails from summer broods have much longer tails than those from spring broods. Click on these pictures to get a better look at just how long those tails are.







ps: here’s a picture of a pawpaw flower; around here, they bloom from about mid April to mid May

Astery Things #3: New York Ironweed

Growing along the fence with the joe-pye weeds in my garden is another oddball asteraceous species: Vernonia noveboracensis, or New York iron weed.

Like the joe-pye species, the inflorescence of NY ironweed consists only of disk florets; there are no rays at all. And what a great example of this kind of flower it is: look closely and you can see how five narrow petals, fused at the base, form a corolla, from which a split style pops way out.

There are two native species in MD; the other one, broad-leaved ironweed (V. glauca), is found in a few locations in the eastern Piedmont and in the Coastal Plain, while New York ironweed is found throughout the state. There’s also an alien, Arkansas ironweed (V. arkansana) reported in one location in the Coastal Plain.

New York ironweed’s native range is from southern New England into northern Florida and west into central Kentucky and Tennessee (and in one county way out in northern New Mexico). It’s listed “special concern” in Kentucky and “presumed extirpated” in Ohio.

Often described as “coarse” in texture, this is a tall forb – over six feet in ideal conditions – with an open habit. It likes moist to wet soils; in the wild you’ll find it growing along river banks, in the full sun or dappled shade.

In the garden site it where it will get enough sun and water, in the back since it gets so tall, or along a fence. It doesn’t attract butterflies as well as the joe-pye weeds do, but bees go crazy for it. And it blooms for a long time.

I was trying to get good, clear close-up shots of the flowers, with the camera mounted on a tripod, but something large and white kept moving around in the upper reaches of the plants. As soon as I realized what it was I took the camera in hand and tried to get pictures of yet another type of butterfly. It never stayed still, so all the shots were lousy and I was pretty bummed… until the next day. More about that in my next post.

Big Butterflies #2: Dark Wings

eastern tiger swallowtail, dark morph: dorsal view, closeup showing markings on hindwings

While researching butterflies I learned that there are six dark-winged swallowtail species in Maryland: the black, giant, palamedes, pipevine, spicebush, and dark morph eastern tiger.

eastern tiger swallowtail, dark morph: ventral view showing hindwing markings

The dark winged butterfly that I had been shooting on joe-pye weeds [see previous post] was a dark morph eastern tiger swallowtail (Papilio glaucus). The dark morphs are always females.

eastern tiger swallowtail, dark morph: ventral view showing body


Several characteristics distinguish dark morphs from other butterflies with dark wings, but the one that’s a dead giveaway is the lack of white spots on the body.

eastern tiger swallowtail, dark morph: ventral view showing white “dashes” on wings





Also note that the white marks on the trailing edge of the forewing are elongated: dashes rather than spots.

dorsal view










It wasn’t until the next day, while I was shooting yet another species of butterfly (subject of a future post), that I saw what I thought was a spicebush swallowtail (Papilio troilus). I didn’t even realize at the time that’s what it was, because I was so focused on the other one that I didn’t stop to think that this particular butterfly was actually resting on a spicebush.

ventral view


Note the round spots on the body, and also the fingertip-shaped bluish markings at the trailing edge of the hindwing. The lack of a lighter patch in front of those blue marks indicates that this is a female. SEE UPDATE BELOW.

Spicebush swallowtails range from eastern Texas north into the Midwest and southern New England, and south into Florida. Several species of plants host the caterpillars, most notably spicebush (Lindera benzoin). Adults feed on quite a few different plant species, including some exotics; among the native species are milkweeds, dogbanes, and thistles.

another dorsal view

I’m totally kicking myself for not hopping the fence that was in my way to get better pictures. I’ve checked my spicebushes several times each day since then, but haven’t seen another butterfly on them.



giant swallowtail


Here’s a giant swallowtail (Papilio cresphontes) that I photographed in the eastern panhandle of West Virginia a few years ago. I’ve never seen one of these around my house; they are found in most of Maryland, but are fairly rare.


pipevine swallowtail

I believe this last one to be a pipevine swallowtail (Battus philenor). The plants it’s on are Aristolochia fimbriata, white-veined Dutchman’s pipe, a South American species that’s growing in the Enid A. Haupt Garden next to the Freer Gallery of Art in Washington, DC. Aristolochia species are hosts for the pipevine swallowtail, and so the gardeners in the Haupt and the nearby Mary Livingston Ripley Garden have been growing them for several years now, in order to attract the butterflies. Smithsonian Gardens has some wonderful spaces around the Mall, but I’m digressing.

UPDATE 8/22/18: The second butterfly is NOT a spicebush swallowtail. I failed to see something obvious. Pictured is the almost-identical red-spotted purple (Limenitis arthemis).

I checked many resources for help understanding butterfly identification; particularly useful sites included