Identifying the Violets of Manhattan (New York County)

With March drawing to a close, a tiny violet caught my attention in a concrete Hudson River Park flower bed. I didn't recognize it, which reminded me that I'd been meaning to learn more about the violets of Manhattan. I've always loved violets -- they're so familiar, and yet challenging. (And they can be very surprising.)

You can read about New York City's violets in @danielatha's 2018 State of New York City's Plants, but Manhattan doesn't have the wetlands, forests, and beaches of the outer boroughs. Which species thrive, or at least hang on, here in this densest borough?

After analyzing about 1,000 observations in iNaturalist, I've written up 10 species below (one is a twofer). This seems to capture the reported diversity on iNaturalist to date, not counting a couple of isolated cultivated species. There may be more diversity than is reported so far, and I probably haven't got everything quite right, so please weigh in with your comments.

As you observe violets this season, please try to photograph four things:

  1. A front view of the flowers, on their own level (an overhead shot has less ID value);
  2. A profile view of the flowers, to show sepals, spur, and stem;
  3. A closeup of a leaf or two;
  4. The overall habit of the plant (basal leaves only? stem leaves?) with a size reference.

All photos in this post are clickable -- the links will take you to the original observations. Thanks to the photographers for making their pictures available with a Creative Commons license.

Oh, and that violet I found the other day is #3 below.


1. Common Blue Violet (Viola sororia)

Common Blue Violet is an extremely successful and abundant native violet in Manhattan, growing jubilantly in lawns, parks, beds, borders, and between cobblestones and in pavement cracks. It blooms profusely in April and early May. It is the default purple violet anywhere in the borough. It can form dense, thick carpets, and while it may be small in mowed or thin-soiled areas, it can grow several inches tall in favorable locations.

Flowers rise individually from the rhizomes; they are not on arranged on stems with leaves. Leaves are coarse and broad, heart-shaped with a pointed tip and sharp teeth on the margin; they ascend from creeping rhizomes. The purple form has rich, vibrant purple flowers with a touch of bright blue at the base of the petals. There are long, dense hairs on the inside of the two lateral petals, tending to visually obscure the reproductive organs inside the flower. The spur is quite short and blunt, barely protruding behind the flower.

(Update 04/02/2020): The color of the Common Blue Violet is quite variable. Some plants produce flowers with more reddish or pinkish hues, like this gorgeous plum-colored individual below. Note too, as shown in this image, that the first leaves to emerge in spring are blunt-tipped with rounded teeth, and are rather smooth, in contrast to coarser, more angular leaves produced as the season unfolds.

Confederate Violet, or V. s. forma priceana, is a variation of Common Blue Violet with striking white, purple-centered flowers. In all other respects, it resembles the blue form. It is also abundant in the city, and it is frequently misidentified as many other species from all over the world.


2. Eurasian Sweet Violet (Viola odorata )

The introduced Eurasian Sweet Violet is very fragrant -- the quintessential violet scent -- which is a good clue to its identity. Working from photographs can be a bit harder, particularly since most people shoot violets from above. The leaves, which are kidney-shaped with scalloped margins, form a basal rosette; the flowers grow individually from the base of the plant. The flowers are purple, or sometimes white or pink, and have minimal hair on the lateral petals so that the reproductive organs are clearly visible (unlike V. sororia in which the hairs are much longer): https://www.labunix.uqam.ca/~fg/MyFlora/Violaceae/Odorata/odorata.e.shtml.

This species is said to be naturalized in New York. However, having gone through all the records in iNaturalist, I can't find a lot of evidence for it. Most plants are either clearly V. sororia or are ambiguous at best (especially since the first leaves of V. sororia early in the season can appear smaller and more rounded, more like those of V. odorata).

This beautiful pink-flowered plant below, posted by @aberkov does indeed appear to be V. odorata (again, most V. odorata flowers are purple); it's not clear whether it's wild or cultivated. (Update 03/29/20: aberkov confirmed that the plant pictured below is cultivated. I now believe that V. odorata is extirpated in our region, except where reintroduced in cultivation. Here's a map of Research Grade observations in the Northeast -- the species is effectively absent away from western New York and southern Ontario, which is amazing: https://www.inaturalist.org/observations?nelat=44.722601203578094&nelng=-65.8714934438467&place_id=any&quality_grade=research&swlat=40.2703715944484&swlng=-81.5270110219717&taxon_id=55845. What accounts for this I wonder?)


3. European Dog Violet (Viola riviniana Purpurem Group)

The European Dog Violet has a purple-leaved form that is used in the horticultural trade and is sometimes sold as V. labradorica, which is an incorrect name for this plant because V. labradorica is a different violet native to northeastern North America.

Apparently this plant can self-seed and become weedy under some conditions. There is some evidence from iNaturalist observations that it occurs in and around cultivated areas in Manhattan (https://www.inaturalist.org/observations?ident_taxon_id=61481&place_id=1264&subview=grid), though it is not listed as an established species in NYBG's 2018 State of the City's Plants report. This is a small plant with purple-tinged, somewhat fleshy-looking foliage, leaves on the flower stalk, pointed sepals, and slender, violet-purple blooms with long spurs and only short hairs in the flower's throat, revealing the round-tipped style.

See discussion of this plant here: https://www.houzz.com/discussions/2209751/viola-labradorica-purpurea-v-riviniana-what-s-the-story and here: https://davesgarden.com/guides/pf/go/1415/#b.


4. Bird's Foot Violet (Viola pedata)

I believe the few observations of the rare and beautiful Bird's Foot Violet in Manhattan are plants growing in native plant gardens: https://www.inaturalist.org/observations?locale=en-US&place_id=1264&preferred_place_id=1&subview=grid&taxon_id=82536. The flower and leaf shape together are distinctive.


5. Downy Yellow Violet (Viola pubescens)

Aptly named, the Downy Yellow Violet bears bright yellow flowers on hairy stems. The plant sends up a long stem, and flowers grow from the leaf axils along the stem. Basal leaves are usually absent.

This species is loosely cultivated in Central Park and a few other parks in Manhattan; it's used in restoration plantings and can be found in the Ramble and Hallett Nature Sanctuary. It's been cultivated in the park since at least 1865, but appears to depend on human intervention for survival in this heavily altered landscape. It seems that iNatters have different opinions on whether this and the following two species should be marked "cultivated" or "wild." Here's a photo shot from @lisabrundage:


6. Canada Violet (Viola canadensis)

The tall and striking Canada Violet, like Downy Yellow Violet above, depends on human intervention to thrive in Central Park, but thrive it seems to do. Because the species appears to spread on its own in areas where it has been planted, some iNatters believe it should be considered wild for the purposes of iNaturalist. This is a leggy plant, with leaves and flowers sprouting off the stem. Flowers are white with a yellow center and purple backs on the top two petals, setting this species apart from the following species. Here's a nice shot from @ansel_oommen:


7. Cream Violet (Viola striata)

Cream Violet is another restoration species in Central Park, present because people brought it there in the last few decades to restore wooded areas. It could be confused with Canada Violet (above), but it lacks yellow color in the mouth of the flower and the back of the petals is all white.


8. European Field Pansy (Viola arvensis)

The small, pale European Field Pansy is, as its name suggests, introduced from Europe. It typically has flowers a half-inch or so in size that are cream-colored with some yellow on the bottom petal and a few guide marks for pollinators. Its sepals tend to be longer than its petals, making the flower look partially enclosed (http://www.luontoportti.com/suomi/en/kukkakasvit/field-pansy). Some individual plants can look intermediate between this and V. tricolor, which is described next (I'm pondering these, for example: https://www.inaturalist.org/observations/22464945).

There is an American field pansy species, V. bicolor, but it differs in appearance (https://www.illinoiswildflowers.info/prairie/plantx/field_pansy.htm) and apparently has not been recorded from Manhattan.

Here's a V. arvensis example from @jholmes; note the long sepals and bicolored flower:


9. Wild Pansy (Viola tricolor)

Wild Pansy, also known as Johnny-Jump-Up and Heartsease, is a Eurasian plant that has been introduced into North America. It appears to be uncommon around Manhattan. It is also an ancestor of many cultivated pansy plants as you can see in the section below, and those should be identified appropriately in iNaturalist. Naturalized V. tricolor generally show tricolored purple, white, and yellow flowers with purple rays. They tend to be larger and more colorful than the previous species, with sepals that are not longer than the petals (http://www.luontoportti.com/suomi/en/kukkakasvit/wild-pansy). This is naturally a very variable species, and I also wonder whether some of these plants are coming from self-seeding ornamentals that slowly revert to a more ancestral form (e.g., this observation of @susanhewitt's https://www.inaturalist.org/observations/23495579).

Here's a photo from me:


10. Garden Pansies (Viola wittrockiana) and "Violas"

Is there anything as cheerful as the big, colorful, ruffled face of a Garden Pansy? These large-flowered garden plants are horticultural hybrids going back hundreds of years. They have been bred in colors from white to nearly black, with a wide range of colors in between, and they often have a dark blotch in the middle of a lighter-colored flower, such as burgundy on yellow.

Garden Pansies are a very common sight during cooler months in Manhattan in pots, window boxes, and planters; around street trees; and in flower beds. They should be marked "cultivated" in iNaturalist; they do not naturalize. See discussion about their taxonomic history under a recent taxonomic swap: https://www.inaturalist.org/taxon_changes/73692. Here's a recent observation from @susanhewitt:

But not all pansy-like ornamentals that you encounter in Manhattan are true Viola wittrockiana. A range of smaller, sometimes striped, and variously colored plants commercially known as "violas" are prevalent as well. They often take over in summer after Garden Pansies fade. These ornamental plants are derived from European V. cornuta and V. tricolor (see https://ufdcimages.uflib.ufl.edu/IR/00/00/17/73/00001/EP32700.pdf and https://www.americanvioletsociety.org/Registry/Cultivar_Registry_Classification.htm section B2).

I would suggest that we identify them on iNaturalist as Melanium, which is the pansy section of the genus Viola, and they should be marked as cultivated. Here's an example from @olibr_:


That's all for now. I'll probably update this post periodically as we learn more. Let me know what you think, and if you want to try your hand at IDing some violets, click here: https://www.inaturalist.org/observations/identify?taxon_id=50829&place_id=148950.

Tagging some more of you that I think will be interested: @srall @elevine @sadawolk @mertensia @oxalismtp @tsn @zihaowang @klodonnell @wayne_fidler @elizajsyh @nycnatureobserver @craghorne @spritelink @irag @andrew_garn @kai_schablewski @ballardh

Posted by djringer djringer, March 29, 2020 11:25

Observations

Photos / Sounds

What

Common Dog-Violet Viola riviniana

Observer

djringer

Date

March 27, 2020 04:52 PM EDT

Description

Growing in a raised bed at the base of an ornamental plant of some sort. “Purpureum group” ornamental form of this European species. Perhaps introduced in garden soil during planting or cultivation of the bed? One very small plant (finger tip for scale in last image)—not a deliberately cultivated species here as far as I can tell.

Comments

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awesome, thanks for tagging me!

Posted by srall 5 months ago (Flag)
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Very helpful. Thank you for putting these notes together!

Posted by tsn 5 months ago (Flag)
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Wow, a very impressive and very useful gathering of information. Thank you David! I had no idea what the choices were really, but now I will understand a bit better what I am seeing. :)

Posted by susanhewitt 5 months ago (Flag)
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Another great post! Quite helpful. Thanks for tagging me!

Posted by klodonnell 5 months ago (Flag)
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Thanks for the helpful post!

Posted by aberkov 5 months ago (Flag)
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Thank you for this great resource!

Posted by elizajsyh 5 months ago (Flag)
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Thanks for sharing information, insight and enthusiasm ... and that awesome link to the Chilean observation (under the words “very surprising” above).

Posted by elevine 5 months ago (Flag)
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Fantastic guide! Thank you so much.

Posted by lisabrundage 4 months ago (Flag)

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