Two Yellow Violets

Since violets (Viola species) hybridize so readily, they can be tricky to identify. Individual plants sometimes show characteristics intermediate between two species. Take a look at the USDA PLANTS Database page for Viola and you’ll see what I mean: of the 129 species shown there, 43 are hybrids. (Presumably these are naturally occurring hybrids, not cultivated varieties.)

Yellow violets are easier, because there are only a few species, and only three of those are found in Maryland. Right now, one of them is blooming in the Potomac gorge area: smooth yellow violet (Viola pubescens var. scabriuscula, formerly known as Viola pensylvanica). There’s a second variety of the same species that’s commonly called downy yellow violet (V. pubescens var. pubescens).

I started writing this post almost a year ago, then realized I didn’t have any good photos for it, so set it aside until now. Over the last few days I’ve examined a few dozen yellow violets, and they’ve all been the smooth variety. I hoped to have photos of both for this post, but if I wait too long I’ll have to set it aside again, so here goes.

The two varieties bloom at about the same time (April) and grow in the same habitat (moist deciduous woodlands). The main difference between the two is hinted at in the name: in botany, pubescent means covered in short hair, while scabriuscula means slightly rough.

Although this one is smooth yellow violet, you can see some pubescence on the leaf base and adjoining stem on the lower right leaf. Smooth yellow violet can have a slight pubescence but is mostly glabrous (smooth), which you can see on the rest of this plant.


Another identifying characteristic is the shape of the stipules. Those of downy yellow violet are broadly oval, with a blunt tip, while those of smooth yellow violet are narrowly oval, with a pointed tip, as shown here. (A stipule is a small, leaf-like bit of tissue found where the petiole meets the main stem; there’s one in the very center of this photo.)

Finally, look at the whole plant: downy yellow has a single flowering stem, with one basal leaf or none, while smooth yellow has two or more flowering stems and one to three basal leaves.* The plant pictured here appears to have three basal leaves (at one o’clock, six o’clock, and eleven o’clock), one flowering stem with a blossom and a bud (seven o’clock), and a second flowering stem still developing (twelve o-clock).

I’ll keep looking at yellow violets this spring, and if I find any of the the downy variety I’ll write a follow-up post.

*descriptions from the Flora Novae Angliae by way of the New England Wildflower Society’s gobotany website (which every botanerd should bookmark):

1a.  Stems solitary, with 0 or 1 basal leaves; leaf blades densely pubescent; stipules broad-ovate, with an obtuse apex … 21a. V. pubescens var. pubescens

1b.  Stems 2 or more from the apex of the rhizome, with 1–3 basal leaves; leaf blades glabrous or sparsely pubescent; stipules lanceolate to narrow-ovate, with an acute apex [Fig. 935] 
 … 21b. V. pubescens var. scabriuscula Torr. & Gray

When One Color Isn’t Enough (part one)

More pictures to keep us dreaming of warmer weather. This time, spring-blooming multi-colored flowers.

Erigenia bulbosa (harbinger-of-spring; Apiaceae)

This is one of our earliest blooming native plants (the only one I can think of that blooms earlier is skunk cabbage). These anthers turn quickly from dark red to black, giving rise to another common name, pepper-and-salt.

Mertensia virginica (Virginia bluebells; Boraginaceae)

That’s right, bluebells again, because here they are in several different colors all in one clump. I can’t wait to see them again.

Galearis spectabilis (showy orchis; Orchidaceae)

This surprisingly common terrestrial orchid grows in all the physiographic provinces in Maryland, but we have the most records for it in the piedmont and coastal plain. Look for it blooming in April and May in rich, moist soils in wooded areas.

Viola sororia (common blue violet, white form ; Violaceae)

Common blue violets are, well, pretty common around here. They seem quite fond of edge areas and open woodlands, always in moist soils. They can be found all over Maryland, blooming from late March into early May.

Cypripedium acaule (pink lady’s slipper; Orchidaceae)

Like most orchids, pink lady’s slipper has specific growing requirements, which means you won’t find it just anywhere. But it does grow pretty much all over the state. Look for it flowering in early May, in rich, undisturbed woodland soils.

Penstemon hirsutus (hairy beardtongue; Plantaginaceae)

This bizarre-looking flower is found mostly in the northern part of Maryland, but there’s a reliable stand on the Billy Goat B trail. Look for it in lean soils (rocky areas) in full sun light, blooming from early to late May.

Mitchella repens (partridgeberry; Rubiaceae) [click on this one!]

What can I write about partridgeberry that I haven’t written before? This is one of my very favorites; I go looking for it every year at the end of May. The plants grow very long but stay very low, creeping along rocks. We have records for it in every Maryland county.

Thalictrum coriaceum (maid-of-the-mist; Ranunculaceae)

Although it isn’t on the Maryland RTE list, we only have records for it in three quads in Montgomery County. I think that’s rather odd, and suspect it’s due to misidentification (see The Botanerd’s Handy Guide to Thalictrum Species). That bright pink on the sepals and filaments turns quickly to brown.


Continuing with pretty pictures during this cold season. It’s a thin line between blue and purple. Color is a continuum. Color is in the eye of the beholder. If some of these look more blue or pink than purple, well, c’est la vie.

Triodanis perfoliata (Venus’ looking glass; Campanulaceae)

Look for this annual forb growing in rocky places where there isn’t much competition from other plants. It generally blooms from about mid May into early June here in the Maryland piedmont.

Clinopodium vulgare (wild basil; Lamiaceae)

A perennial forb with circumboreal distribution. Look for the flowers in the height of summer.



Cunila origanoides (common dittany; Lamiaceae)

A perennial native to North America, and found mostly in the mid West and mid Atlantic. It blooms in late summer.


Elephantopus caroliniana (Carolina elephant’s foot; Asteraceae)

A rather weedy-looking plant with a fascinating inflorescence. Click on the picture and look closely; you’ll see that this is actually four disk flowers, each with a five-lobed corolla. The species is native to the southeastern US (Maryland is almost as far north as it goes). It blooms in late summer.


Eutrochium purpureum (sweet joe-pye weed; Asteraceae).

The joe-pye weeds (formerly Eupatorium species) are perennials that love wet places, but this particular species tolerates drier soils and is a great native for the home garden, with dramatic heads of colorful flowers towering above most other forbs. And it attracts butterflies. Blooms in late summer.

Mentha arvensis (field mint; Lamiaceae)

Another mint-family plant with circumboreal distribution. Another late-summer bloomer.



Mimulus alatus (winged monkeyflower; Phrymaceae)

Watch for this wetland plant and its almost identical cousin M. ringens var. ringens (Allegheny monkeyflower) blooming in early to mid summer.


Monarda fistulosa (wild bergamot; Lamiaceae)

The mint family sure is represented well here. Look for it in mid summer, possibly covered in bees and butterflies.


Phlox divaricata (woodland phlox, wild blue phlox; Polemoniaceae)

As you can see this flower ranges from almost white through lighter and stronger shades of blue and purple. They bloom at about the same time as Virginia bluebells. Bluebells grow in the floodplain while this phlox grows just upland of the floodplain, in still moist (but not wet) woodland soils.

Physostegia virginiana (obedient plant; Lamiaceae)

Yet another mint family mid summer bloomer. Watch for it on rocky outcrops and gravel bars in the Potomac.





Ruellia caroliniensis (hairy wild petunia; Acanthaceae)

In Maryland this species is found mostly in the Coastal Plain; in the piedmont it’s restricted to a few sites near the Potomac River (as far as I know – please leave a comment if you know otherwise). Watch for it in late spring and early summer.

Trichostema dichotomum (forked bluecurls; Lamiaceae)

Blue or purple, or splitting the difference? Whatever. This is a most striking plant, one of those OMG finds. Well it was for me, anyway. What a lurid color. Late summer, dry soils, open areas. Yow.

Verbena hastata (blue vervain, swamp verbena, Verbenaceae)

As one of the common names suggests, you’ll find this in wetlands, blooming anywhere from late June to mid August. This is an extreme closeup; the plants are rather tall but the inflorescences rather small.



Vernonia noveboracensis (New York ironweed; Asteraceae)

All ray flowers with strongly exserted stigmas, no disk flowers. Very tall plant, wispy appearance. Likes wet soils. Blooms in mid to late summer.


Viola palmata (early blue violet, three-loved violet; Violaceae)

Violet taxonomy is in flux, and violet species can be difficult to differentiate. This one is relatively easy because of the unusual leaf shape, although even that can be highly variable. Look for it in mid spring in drier woodlands.

One More Violet

I’ve been so fixated recently on understanding difficult genera that I’ve gotten way behind in posting; there are now a dozen different species that will have to wait until next year, as they’re surely done blooming by now. But since Viola has been one area of focus, I’ll do a quick post about one more species.

As acaulescent blue violets go, this one is easy to identify, because of the unusual leaf shape. It’s Viola palmata, aka early blue violet, cleft violet, or wood violet. In the southern part of the Maryland piedmont it seems to bloom much later than the other blue violets; I’ve seen no sign of those at the Billy Goat Trails, on Sugarloaf Mountain, or at Rachel Carson Conservation Park in the last two weeks.

Note how variable the leaf shape is.

These photos were taken on May 2, along the C&O Canal towpath near the Marsden Tract. I saw this species last year in mid May on Sugarloaf Mountain, so it’s likely to be blooming still.


A Vexing Violet, or, How to Overthink Identification

Ah, violets. How can something so small, delicate, and beautiful be so vexing?

Last year I wrote about Viola blanda (sweet white violet), then updated my post to say that the plant pictured might be Viola primulifolia (primrose-leaved violet). When I went back to Rachel Carson Conservation Park last week, my third goal was to find these plants and get a definitive ID.

I’m so naive.

I did find a nice stand of them, in the same place where I saw a single plant last year. With Weakley’s Flora* downloaded to iBooks on my iPhone, I perched on a rock near the trail, took out my hand lens and measuring tape, and got to work.

First step: read about the genus.

Identification notes: Viola has presented numerous problems in taxonomy, distribution, and identification…

Oh, yay. But, I knew this.

Particularly troublesome are the so- called “acaulescent blue violets”, including V. sororia, V. sagittata, V. palmata, V. septemloba, etc. They may be difficult to identify due to morphological overlap, or trying to key plants without mature leaves; in some instances hybridization may be suspect. Leaf maturity is an important feature to recognize–the earliest 1-2 leaves produced in most of these taxa are generally ovate-cordate in outline and may not display characteristic lobing, toothing, or pubescence until more mature leaves are produced, 1-2 weeks later. Specimens thus collected early in the flowering period can present the botanist with a perplexing series of plants that do not key cleanly. [emphasis mine]

Interesting, and worth keeping in mind about leaf morphology and maturity, but I was looking at white violets, not blue. So continuing…

A second troublesome group contains the small white violets, including V. blanda, V. incognita, and V. macloskeyi. These taxa have been dealt with in various ways, but resist a wholly satisfactory treatment, due to apparent hybridization…

So now what? Soldier on, use the keys. There are four of them. Four keys for a single genus.

Key C – Acaulescent Violets with stolons and white (or rarely blue) flowers

That’s the one. “Acaulescent” means “without stem”. This amuses me, because violets have stems. A major distinguishing feature among violets is that some have only basal leaves, while others have caulescent leaves (leaves on the flowering stems). I’m not sure why basal-only is termed “acaulescent”, but whatever. These plants had white flowers and no stem leaves, so Key C it was.

First couplet:

1. Flowers generally blue…
1. Flowers white…

Hey, this is easy! Second couplet:

2. Leaf blades > 1.5× as long as broad.
2. Leaf blades < 1.5× as long as broad.

Got the measuring tape, checked a few leaves… uh oh. Which leaves to measure? Each plant had several low leaves and a single larger, more upright leaf. Is that the mature leaf I should be measuring? “Leaf maturity is an important feature to recognize…” Oh, right. So I measured a few mature leaves and found that on average, they are exactly one and a half times as long as they are broad. (A few are very slightly more, and a few are very slightly less.)

The thing about nature is that it refuses to be put into neat categories. Keys are great, but they can never account for every variation. When using keys the rule is: examine multiple specimens and go with the best fit, even if it isn’t a precise fit. But I really didn’t know where to go here, so I decided to follow both leads to see what happens.

The first line of the couplet above leads to

3. Leaf blades ovate-lanceolate to ovate-triangular, 1.5-2× as long as broad, the base broadly rounded to subtruncate…  V. primulifolia 
3. Leaf blades lanceolate to linear-lanceolate, 3-15× as long as broad, base narrowly cuneate and somewhat decurrent onto petiole.

This had me scratching my head. For the most part the leaves were more ovate-triangular (first line), but the bases were more often cuneate and decurrent (second line). Since neither of these descriptions quite fit, but the first one was closer, I kept it in mind as a possibility and went back to the second line of couplet two (leaf blades less than one and a half times long as broad):

5. Leaf blades completely glabrous (petioles may be villous); [of wet, acidic seepage or swampy woods, often with Sphagnum]…   V. pallens
5. Leaf blades pubescent, at least on the upper surface of the basal lobes; [of wet to more mesic situations]

Most of the leaves were slightly to very pubescent. Also, these plants were found in a wet area, so the habitat description works, too. I chose the second line, which led to:

6. Lateral petals glabrous within; petioles and peduncles usually reddish-tinged; leaf apex acute; basal lobes of the leaf often overlapping; pubescence of the upper leaf surface often restricted to the basal lobes; [of mesic, often nutrient-rich forests]… V. blanda
6. Lateral petals bearded within; petioles and reduncles [sic] green; leaf apex obtuse to rounded; basal lobes of the leaf not overlapping; pubescence of the upper leaf surface usually widespread; [of mesic to wet situations]… V. incognita

The lateral petals were very slightly bearded, not glabrous, but the petioles and peduncles were reddish-tinged; the leaf tips were acute, but the basal lobes of the leaves were not overlapping. The pubescence was more widespread on some plants than others.

At this point I didn’t know what to think, so I turned to the internet and a few books to get descriptions of V. primulifolia and V. blanda. I’ll spare you the details, other than to say that according to Illinois Wildflowers, V. primulifolia sometimes has slightly bearded petals.

In the end it came down to looking at pictures. From all that I saw, the mature leaves of these plants look a lot more like V. primulifolia. The final check was location: are the two species found in Montgomery County? V. primulifolia is, V. blanda is not.

So with the information available and my understanding of the terminology, I’ve reached the conclusion that these are primrose-leaved violet.

Going through an exercise like this is tedious, but I do it in part to teach myself botany. How else can we learn but to question everything? I welcome discussion in the comments section, especially if you think I got something wrong.

*Weakley’s Flora can be downloaded from the University of North Carolina Herbarium website