No, Really, It’s Still June: Knock it Off!

What is going on with the asters and sunflowers this year? It’s really too early for them to be blooming. First there was Ionactis linariifolius, then the Solidago species, and now this.

I’ve been visiting this same spot near Carderock for five years now. The earliest I’ve ever seen woodland sunflower (Helianthus divaricatus) blooming was late July.

Of the seven or so Helianthus species found in the Maryland piedmont, this is the only one with sessile, entire, opposite leaves, making identification pretty easy.

My Bane: the Fleabanes

This spring I’ve spent hours and hours and hours taking pictures of fleabanes and reading about fleabanes and studying fleabanes, all with the intent of writing a detailed post with tips for field identification. It didn’t seem like I was making any progress… until I started writing this post anyway. The act of attempting to explain something forces me to think about it clearly and organize the details, and with that comes deeper understanding. Also with that came the realization that I have no pictures of Robin’s plantain, and it’s done blooming for the year probably, so gah! Maybe next year.

Erigeron flowers look like daisies, but with many more rays. Four species of them are found in the Maryland Piedmont. Here’s a brief summary of their characteristics.

Erigeron annuus (annual fleabane, daisy fleabane)

Usually the tallest of the fleabanes, though height is variable. The literature says this one grows to three and a half feet tall, but I’ve seen them much taller than that. The stem is generally sparsely hairy, and the hairs are generally spreading (but descriptions vary a lot). The stem may branch near the top; overall the plant may produce as many as 50 flower heads. The basal rosette of leaves usually withers by the time the plant flowers. The stem bears many leaves along its entire length. The lower ones are large, toothed, and have petioles, while the upper ones are a little if at all smaller, slightly toothed or maybe entire, and sessile. The leaves are lanceolate to oblong. The flowers have anywhere from 50 to 120 rays; flower buds are conspicuously hairy. They bloom from summer into fall, on and off, and like disturbed, weedy areas.

E. annuus: sparsely hairy stem, hairs spreading

E. annuus: leafy throughout

E. annuus: coarse-toothed lower stem leaf with winged petiole

E. annuus: flowerhead next to H. sapiens thumb for size

Erigeron philadelphicus (common fleabane)

This one can reach two and a half feet in height, with sparsely hairy stems that may branch near the top. The oblanceolate-to-obovate basal leaves may be present during flowering, or may have withered. The stem leaves are variously shaped, from ovate to narrowly elliptic, but they get smaller in size and fewer in number as they ascend the stem. Lower stem leaves may have a few teeth, while upper ones are entire; all leaves may be pubescent to some extent. There are single leafy bracts near the inflorescences. The plants bear from one to 35 flower heads, each with anywhere from 150 to 400 rays, from late spring to mid summer. The plants like moist, disturbed areas (think roadside depressions).

E. philadelphicus: basal leaves and clasping lower stem leaves

E. philadelphicus: upper stem leaf, clasping, entire, with a secondary flowering stem branching off

E. philadelphicus: a small colony

Erigeron pulchellus (Robin’s plantain)
Usually the shortest of the fleabanes, to two feet tall, unbranched and bearing one to nine flower heads, and often described as having a “stout” appearance. The stem is conspicuously hairy along its entire length. The basal rosette of spatulate (spoon-shaped) leaves is present during flowering. The few stems leaves are dentate, somewhat hairy, oblong, and clasping. The flowers are generally the largest of these four fleabanes, up to an inch and a half across, and have 50 to 100 rays. They bloom from mid-spring to early summer, and prefer rocky, less disturbed areas.

I deeply regret that I have no photos of this plant. Having learned how to identify the fleabanes, I went back through all my photos; every one that I had thought might be Robin’s plantain has ended up being common fleabane. There are some very nice, clear pictures on this blog.

Erigeron strigosus (daisy fleabane, prairie fleabane)

This not-commonly-seen fleabane can reach three feet in height, with a stem that may branch near the top. The stem hairiness is described differently by various authorities, but the specific epithet strigosus is taken from the word strigose, which refers to hairs which are short and lie close to the stem, pointing upwards. This is one identifying characteristic of the species. Another is the stem leaves, which are much closer to linear than any of the other species’ leaves. There aren’t many of them. The larger/lower ones may have a few coarse teeth or be crenate, and have long, sometimes winged petioles, while the upper leaves are more likely to be entire and sessile or with short petioles. The basal leaves are usually present during flowering. Each plant can bear 10 to 200 flower heads, each flower with 40 to 100 rays. This species blooms at about the same time as E. philadelphicus (late spring to mid summer), but prefers higher quality habitats.

E. strigosus: mid-stem showing strigose hairs and sessile, elliptic leaf

E. strigosus: more of the mid-stem

Individual plants vary, and each of these species except the annual has 3 or 4 varieties, each with differing characteristics. Identification is not always straightforward. About color: all these species have white flowers, but some can have a pinkish or bluish tint to them. In many species color is an unreliable characteristic, and in these species it should not be considered diagnostic.

There are close to two hundred species of Erigeron in North America, almost all of which are native. E. annuus, E. philadelphicus, and E. strigosus are found in almost every state and province, while E. pulchellus is found on the eastern half of the continent.

Just for fun, here’s E. uniflorus, oneflower fleabane, spotted in Iceland last summer. It’s also found in Alaska, Canada, and Greenland.

Our Earliest Aster

In much the same habitat as Virginia bluebells grows our earliest-blooming aster family species: Packera aurea (formerly Senecio aureus), commonly known as golden ragwort or golden groundsel. It starts blooming about the same time as the bluebells, but in the Potomac Gorge area seems to hit peak bloom just after the bluebells do.

Though they grow together, I’ve noticed that golden ragwort may have a bit more tolerance for slightly drier soils than the bluebells do. In some areas I can see that the land closest to the river is carpeted in bluebells, while a short distance away – on the other side of the trail, for example, where the land starts sloping upward – the carpet changes to ragwort.

Golden ragwort is a colony-forming perennial forb that grows to about two and a half feet tall. The flowers are borne on a corymb ( a more or less flat-topped cluster) and have the typical aster family arrangement of ray flowers and disk flowers.

 

The basal leaves are oval with a cordate base and have scalloped edges and long petioles.

 

 

 

The stem leaves are completely different: narrower, deeply lobed, and sessile or clasping.

 

 

Golden ragwort is one of 57 Packera species native to North America. Look for it growing in moist to wet woodlands in the mid-West, mid-Atlantic, New England, a few parts of the South, and eastern Canada.

The Aster Family (part 5): Odds and Ends

Did you know that there’s a word for the study of the Asteraceae? It’s synantherology. And, a person who studies the Asteraceae is a synantherologist.

I was going to write a post about the lower orders of classification within the aster family. But it ends up being unusually complicated, with various authors positing sub-families, super-tribes, tribes, sub-tribes, and even sub-genera as ranks between family and species. If you’re really interested, check out the Asteraceae page at the Tree of Life Web Project, or Classification of Compositae from the International Compositae Alliance.

So rather than another detour into taxonomy, here’s a gallery of aster family oddballs: flowers that might not look like composites at first glance.

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Anaphalis margaritacea
pearly everlasting

Maryland Biodiversity Project has only 2 records for this plant, including one in the piedmont, so it’s unlikely you’ll see it in this area. But you’ll see it often in floral arrangements. The yellow-ish centers are the disk florets, and the white outer parts are bracts; there are no ray florets.20140915-DSC_0024


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Antennaria plantaginifolia
plantain-leaved pussytoes

This plant is found throughout the Maryland piedmont. White disk florets only, surrounded by green phyllaries. Look at those little seeds!
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Elephantopus carolinianus
Carolina elephant’s foot

Found throughout the Maryland piedmont. Click on the image and then zoom in to see the details: this head is showing four individual disk florets, each with a five-lobed corolla. There are no ray florets.

 

 


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Erechtites hieraciifolius var. hieraciifolius
pilewort; fireweed; burnweed

Found throughout the Maryland piedmont. My apologies for not having a clearer picture. The flower heads contain disk florets only (no ray florets).


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Conoclinium coelestinum
blue mistflower
(with eastern tailed-blue butterfly)

Found throughout the Maryland piedmont. Disk florets only.

 

 


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Eutrochium purpureum
sweet joe-pye weed
(with eastern swallowtail butterfly)

Found in most of the Maryland piedmont.  Disk florets only.
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The Aster Family (part 4)

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Tragopogon (goatsbeard) species (I think)

 

 

Each floret of a composite family plant produces a single fruit (which contains a single seed) called a cypsela. In many texts and on-line sources, the term achene is used. The difference between the two is technical (it depends on the position of the ovary), and for years both were used rather loosely. While trying to make sense of this I tripped over an article in the Brazilian Journal of Botany, the poorly translated abstract for which reads

The worry about the indiscriminate use of the terms cypsela and achene for the fruits of Asteraceae has been frequently detached by specialists in this family. The present work was developed aiming to verify the existence of arguments to justify the adoption of a term against the other. After historical and anatomical analysis, we concluded that there is technical basis to consider cypsela and achene as different types of fruits. For Asteraceae, the correct is to call cypsela; achenes are only derived from superior ovaries, as in Plumbaginaceae.

At any rate, picture a single small seed with a tuft of hairs, like dandelions have.

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Erechtites hieracifolius (pilewort)

 

 

That’s pretty much it, unless there are barbs instead of hairs:

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Bidens bipinnata (Spanish needles); note the capitulum (flower head) with yellow ray and disk florets at top, another flower head showing the phyllaries in the middle, and the barbed cypsela at the lower right

 

 

next: lower classifications

The Aster Family (part 3)

There are three types of aster family flower heads, named according to the type(s) of florets present.

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If both types of florets (ray or ligulate and disk) are present in a head, the arrangement is termed radiate.

Verbesina alternifolia
(wingstem)

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If a head contains rays only, it is called ligulate.

Hieracium venosum
(rattlesnake weed)

 

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And if only disk florets are present, a head is called discoid.

Vernonia noveboracensis
(New York ironweed)

 

Another characteristic of aster flower heads is the presence of phyllaries.

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Symphyotrichum species, possibly S. oblongifolium 
(aster)

 

 

At the base of a flowerhead there’s a whorl of bracts (modified leaves), called an involucre. In aster family plants only, the individual leaf-like structures are called phyllaries. The number of phyllaries, how they’re arranged (how many rows), the shape, presence of hairs, and other fine details are characteristics used to distinguish certain species from others [see this recent post about tickseed].

Symphyotrichum species
(aster)

next: aster fruits/seeds

The Aster Family (part one)

From golden ragwort in April to goldentop in October, about one in five flowering plant species that I find in the Maryland Piedmont is in the aster family.

It’s unknown how many plant species there are altogether: discoveries still happen, and of course there’s taxonomic uncertainty. But experts believe that there are about 352,000 flowering plant species (angiosperms), and of the other major plant groups, there are an estimated 1,000 species of conifers and conifer allies (gymnosperms), 13,000 species of ferns and fern allies (pteridophytes), and 20,000 species of mosses and liverworts (bryophytes). [The Plant List]. So it’s probably safe to say that flowering plant species outnumber all other plant species combined by an order of magnitude.

Of the flowering plant families, the Asteraceae is probably the largest with about 23,600 species in 1,620 genera. [Encyclopedia of Life]  Whether or not it actually is the largest depends on the current state of taxonomic science; the other contender is the Orchidaceae.

There are 2,401 native Asteraceae species in North America. [BONAP] The Maryland Biodiversity Project lists 373 Asteraceae species (native and alien) in Maryland, and by my very rough estimate, about half of these can be found in the Piedmont.

So what are the characteristics of aster family flowers?  Have a look at this Jerusalem artichoke:

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How many flowers do you see? If I zoom in I can see about 21, not counting the unopened buds.

Wondering how that can be? Here’s a clue: an older but still accepted name for this family is Compositae, or composites. Plants in this family bear heads that appear to be single flowers, but these heads comprise from several dozen to several hundred individual flowers.

next time: aster family floral morphology

This post is dedicated to my friends Cheryl and Barry, who independent of each other gave me the idea to write about plant families during the dormant season.