Keys to Nature
Project
Key to Violets of the Chicago Region - Amateur Version


© John & Jane Balaban, Viola pubescens & Viola sp. - Keys to Nature Project

Title:
Key to Violets of the Chicago Region - Amateur Version
Version:
142
Author(s):
William Alverson, Jennie Kluse, Harvey Ballard
Email:
walverson@fieldmuseum.org
Description:
This tool is designed to help amateurs identify flowering violets (the genus Viola) in the Chicago Region. It was put together by Bil Alverson and Jennie Kluse, based on Harvey E. Ballard Jr.'s publication, The Violets of Michigan (see pages 131 - 197 of The Michigan Botanist, 1994). NOTE: A group of violets called the "stemless blues" has been given an alternative taxonomic treatment by Dr. Nir L. Gil-ad, who has different concepts of some of the species. Begin his key, Key to the "Stemless Blue" Violets, Subsection Boreali-Americanae, of the Chicago Region - Expert Version, from the Keys to Nature homepage, or by copying and pasting the following URL to your browser: http://fm1.fieldmuseum.org/keystonature/blueviolets/.

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Key Structure:
1. Plant with above-ground stems; the leaves and flowers grow out of these vertical or ascending stems - 2.
1. Plant with no above-ground stem; the leaves and flowers arise separately out of the ground, directly from the rootstock - 10.

2. Corolla solid yellow, or white with yellow center; edges of stipules smooth or jagged - 3.
2. Corolla cream-white to yellow-orange, or lavender to blue, with or without yellow center; edges of stipules fringed or deeply lobed - 4.

3. Corolla white with yellow center; stipules more slender, tapered from base to tip, shriveled-dry in texture - V. canadensis
3. Corolla solid yellow; stipules broader, commonly broader above base and then narrowing towards the tip, soft-leafy in texture - V. pubescens

4. Stipules deeply lobed near base with oblong or spoon-like segments at least 1/4 as long as whole stipule - 5.
4. Stipules fringed with thread-like or triangular segments less than 1/4 as long as whole stipule - 7.

5. Corolla pale blue with yellow center; flowers less than 1 1/2 cm long; lateral petals about twice as long as sepals - V. rafinesquii (V. bicolor)
5. Corolla cream or yellow-orange with yellow center; upper petals sometimes dark blue at tips; if flowers less than 1 1/2 cm long, then lateral petals nearly length of sepals - 6.

6. Petals shorter (or up to 2 mm longer) than the sepals; all five petals cream-colored towards tips and about equal in length - V. arvensis
6. Petals longer than sepals, the upper petals dark blue or purple towards tips, and longer than the other three petals - V. tricolor

7. Leaves more slender (narrowly egg-shaped to triangular in outline), more or less squared off at base, and with edges mostly smooth; corolla dark blue; leaves often densely covered with tiny, short, soft hairs - V. adunca
7. Leaves broader (egg-shaped to kidney-shaped), their edges with rounded or sharp teeth; corolla cream-white, lavender, or light blue in color; leaves hairless or with a few hairs - 8.

8. Corolla solid cream-white; spur of lowest petal less than 4 mm long and up to 1/4 as long as the entire lowest petal; edges of sepals with conspicuous hairs; edges of leaves evenly cut by small rounded teeth - V. striata
8. Corolla light blue or lavender; spur of lowest petal commonly over 5 mm long, more than 1/4 as long as the entire lowest petal; edges of sepals without hairs; edges of leaves without small rounded teeth - 9.

9. Corolla solid light blue; lateral petals "bearded" inside with dense clusters of hairs; leaves broadly egg-shaped to kidney-shaped in outline, usually with a broad apex (sometimes with a small, narrow projection at tip), with low rounded teeth along edges - V. labradorica
9. Corolla light blue to lavender with dark purple "eyespot" at center; lateral petals not bearded; leaves egg-shaped in outline (the upper leaves with narrow tips), with a few, widely-separated sharp teeth along their edges - V. rostrata

10. Tip of style hook-shaped; stolons (horizontal stems on surface of ground or just below surface of soil) green, stiff and cord-like; this species is native to Europe but has escaped from gardens into our lawns and woods - V. odorata
10. Tip of style shaped like a short scoop; stolons pale-colored and slender, or no stolons present; native species of natural habitats - 11.

11. Corolla white; spurred petal without hairs on inner face; lateral petals sometimes with dense clusters of hairs ("bearded"); stolons present (except in V. renifolia); top of rootstock less than 3 mm thick - 12.
11. Corolla purple [though albinos do exist fide G. Tonkovich]; lateral petals and, sometimes, spurred petal bearded within (except in V. pedata); stolons never produced; top of rootstocks usually more than 3 mm thick - 15.

12. Leaf blades more than 1 1/2 times as long as broad - 13.
12. Leaf blades less than 1 1/2 times as long as broad (often broader than long) - 14.

13. Leaf blades narrow, lance-shaped, tapering to a narrow base - V. lanceolata
13. Leaf blades broader, with broader bases that are sometimes form lobes at base of leaf - V. xprimulifolia

14. Leaf blades dull (not shiny) on upper surface, hairless on upper and lower surfaces, the underside not paler than the upper surface, orange-tinged when dried; edges of leaves with low rounded teeth or almost without teeth - V. macloskeyi
14. Leaf blades (a) shiny and hairless above and with or without hairs on lower surface, or (b) dull and sparsely to densely hairy both above and below, the underside distinctly paler than the upper surface but not orange-tinged when dried; margins with sharp teeth - V. blanda

15. When viewed from front, living flowers flattened so much that the tips of the orange stamens peek out; lateral petals hairless on inner surfaces; stipules not free, instead fused to stem - V. pedata
15. Living flowers not flatted, rather the petals face forward and cover the stamens; lateral petals bearded within; stipules free, not fused to stem - 16.

16. Leaf blades lobed or divided - 17.
16. Leaf blades toothed along margins but not lobed or divided - 20.

17. Leaf blades divided nearly to base into narrow segments - V. pedatifida
17. Leaf blades with large irregular teeth or with lobes reaching about halfway down the base, which cut the blade into triangular, oval, or kidney-shaped leaf segments - 18.

18. Leaf blades much longer than wide, arrowhead-shaped; the lowest quarter or third of the blades have coarse teeth or lobes; sepals elongate and tapering to narrow tips; spurred petal densely hairy within - V. sagittata
18. Leaf blades barely longer than wide, or about as wide as long; lobes triangular to broad-oval in shape, reaching up to at least the middle of the leaf; sepals more rounded, with blunt tips; spurred petal with few or no hairs within - 19.

19. Early spring (outermost) and late summer (innermost) leaf blades unlobed; central division of mid-season blades unlobed, the lateral divisions lobed [character not yet clear.]- V. xpalmata
19. All leaf blades lobed; central lobe of midseason blades deeply lobed like the lateral divisions [character not yet clear.] - V. xsubsinuata

20. Most or all leaf blades distinctly longer than wide - 21.
20. Most or all leaf blades nearly as wide as long, or wider - 23.

21. Leaves sparsely to densely hairy; sepals usually "ciliate" (with fringe of hairs along their edges); plants growing in dry habitats - V. sagittata
21. Leaves hairless or nearly so; sepals not ciliate; plants growing in wet habitats - 22.

22. Lateral petals with long, thread-like hairs within; spurred petal densely hairy within; young cleistogamous flowers (self-pollinating flowers that never open) on stalks that start off pressed to the ground surface - V. affinis
22. Lateral petals bearded within by short knob-shaped hairs; spurred petal hairless within; young cleistogamous flowers on erect stalks - V. cucullata

23. Sepals long-tapering, with sharply narrow tips and well developed lobes ("auricles"); lateral petals bearded within by short, knob-shaped hairs; spurred petal hairless within; flowers commonly held higher than leaves - V. cucullata
23. Sepals broader, with parallel sides or tapering slightly, with blunt tips and inconspicuous lobes; lateral petals, and often the spurred petals, with dense clusters of long, thread-like hairs within; if spurred petal is hairless within, then the leaves held higher than the flowers - 24.

24. Flowers often held above leaves (especially just after flowering begins); leaves essentially hairless; largest leaf blades with tips mostly blunt or rounded, bases squared off or slightly lobed, and with rounded teeth along margins; spurred petal usually densely hairly within; plants growing in wet, alkaline, open habitats - V. nephrophylla
24. Leaves often held above the flowers; leaves commonly moderately to densely hairy with long, soft hairs; largest leaf blades often with pointed tips, conspicuous lobes at base, and sharp teeth along edges ; spurred petal usually hairless within; plants growing in moist or dry habitats - V. sororia

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This page was last modified on: Sun, 9 Oct 2011 23:23:07 -0500.