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Tuesday, August 21, 2007

Viola conspersa (Dog Violet)

Viola conspersa (Dog Violet) and related "Stemmed" blue violas from Eastern North America

Our friend Kim Blaxland who is especially interested in Viola species e-mailed me today to ask me about Viola conspersa plants that we have seen. It seems there is some question whether this is just an upright form of another species and should be lumped with Viola labradorica*/V. adunca v. minor.

Viola conspersa is a relatively upright plant with light blue flowers and leaves scattered up the stem. While the other species have their stems prostrate on the ground.

She asked especially about what kind of rocks and what the soil pH would be. I think I usually have seen V. conspersa on soil derived from diabase (an intrusive igneous rock which usually give rise to circumneutral soils) here in Berks County, PA

The pictures of Viola conspersa here are mine. The first two are from PA State Gamelands #52 (north of Churchtown, Lancaster Co. and south of Maple Grove in Berks Co.) They are growing among and in crevices of diabase boulders along Black Creek. (Kim just e-mailed me and said of the first picture "Lovely photo of V. conspersa! Shows the spurs well, also the purple leaves persistent from the previous year compared with the color of the new spring leaves ."
The last three pictures are from Middle Creek WMA and are in the wet meadow on sandstone derived soils that I though were acid.

If anyone can tell us about locations for Viola conspersa and what kind of soil they are growing in and the parent rock the soil derived from that information would be appreciated.

Kim wrote:

Harvey Ballard, violet expert from Athens Ohio, who wrote the Violaceae treatment in the Flora of Pennsylvania has said that Viola labradorica and Viola adunca v. minor are conspecific and that they merge into Viola conspersa . By Viola labradorica I do not mean the purple-leafed violet of cultivation that is actually Viola riviniana purpurea. I mean the real Viola labradorica as it occurs in Newfoundland, Labrador, Greenland, and high mountains on the Gaspe Peninsula and northern Maine.

I am studying these three species in the NE to try to justify continuing to recognize Viola conspersa as a distinct species.

The stems of V. conspersa do lie down horizontally after flowering, and in autumn the plant will produce new short upright stems in the center from the rhizome.

The two differences I have worked out between V. conspersa and V. adunca v. minor are:
1. Stipules of former are wide lanceolate with very feathered margins, latter narrow lanceolate and either entire or few short teeth/divisions on margin.
2. Rhizome horizontal for former cf. vertical for latter.

V. conspersa does not grow at Shenk's Ferry does it? I've never seen it there. It would be very interesting to test the soil pH at some of these places. Maybe I need to buy a pH meter.

It was interesting writing the descriptions for you, comparing V. appalachiensis with the other three species made me realize that the only differences between them is that V. appalachiensis has rounder leaves, horizontal stems and finer longer peduncles.

The three species, V. adunca minor, V. labradorica and V. conspersa all have vertical stems, its just that those of V. labradorica are much shorter.

Viola adunca v. minor and Viola labradorica both occur on limestone. Viola labradorica reaches a maximum height of only three inches. I saw it growing in shallow depressions in the flat coastal limestone peninsulas at the NW tip of Newfoundland, sheltering for protection from the severe winds. Under these extreme weather conditions it is not surprising that it is so small. Viola adunca v. minor grows taller, to 5-6 inches, in light woods, for example on the Bruce Peninsula, NW of Toronto in Canada. All the morphological characters of these two species are the same except for the overall size. Several stems and a few basal leaves arise vertically from the top of the rhizome. Cauline leaves are evenly distributed up the stems. Leaves are reniform to cordate, stipules entire or with only a few teeth, flowers pale mauve on peduncles from the axils of the leaves on the stem. Fine hairs are on the inside of the lateral petals. The head of the style is bent into a hook with fine hairs on the side near the stigmatic opening. The spur at the back of the lowest petal is tapered, 4-5 mm long. Viola conspersa is usually about the same height as Viola adunca v. minor, flowers are of a similar color but usually slightly larger. The leaves have slightly more cordate bases, and the stipules have more feathered margins, but there do not seem to be enough obvious major differences in morphology to separate these species. However, I have only seen Viola conspersa growing on diabase and sandstone.

Another interesting stemmed violet is Viola appalachiensis that occurs on the Allegheny plateau in western Pennsylvania, also growing in alkaline soils. It grows as a mat forming ground cover because the stems creep horizontally on the ground surface, though usually not rooting from the nodes. The leaves are small and round to reniform. Light mauve flowers are borne from the leaf axils but well above the leaves on tall delicately thin peduncles. The petal spur is tapered and about as long as the three species mentioned above

Two additional notes: 1) V. conspersa x V. striata hybrids thrive where soil has been limed (Dick Lighty pers. comm.) and a note about Diabase soils from NC.
2) Soils derived from the diabase rock (Iredell on uplands and Wilkes sandy loam at the base of the slopes) are quite different from typical Piedmont soils that are acidic or sour soils with a low pH. Soils derived from diabase rocks are basic, or sweet, with a high pH. Sweet soil is ideal for certain kinds of plants typically found in other regions of the United States, particularly in the prairies of the Midwest.

*by the way, as Kim mentions the Viola labradorica wth purplish leaves in cultivation is invariably NOT correctly named. It always turns out to be a selection of Viola riviniana, a European species.

1 comment:

Anonymous said...

I ound the discussion to be useful. Would you please tell me where I can obtain seeds.