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Ruellia humilis 
This prairie native has light lavender petunia-like flowers that are 1 ½ inches in diameter. Wild petunia blooms sporadically from June through October; flowers usually fall off cleanly so deadheading is unnecessary. Wild petunia’s fuzzy green foliage remains ornamental throughout the entire season.
Sanguisorba ‘Red Thunder’ Dozens of burgundy-red, knob-shaped flower heads on wand-like stems, to 30 inches tall; blooms in late July through September. The foliage is pinnately compound. Each medium green leaflet is 2 inches long, lightly textured and toothed. However, when the Japanese beetles start eating holes in the leaves, they become brown and unsightly.
Silene caroliniana var. wherryi ‘Short and Sweet’ 
Silene caroliniana can be found in rocky, calcareous woods and outcrops from New Hampshire to Ohio and south to Missouri and Alabama. It is not found in Illinois. Pink round flowers with wedge-shaped petals less than an inch wide appear from late May through early June (about a two-week bloom period). A cultivar of a native, ‘Short and Sweet’ has flowers that attract nectar-seeking insects and butterflies. The sticky flowering stems give this plant the common name “catchfly.”
Symphyotrichum oblongifolius ‘October Skies’ 
October Skies is a selection of a native to the northeast and has masses of small [about one inch] soft lavender-blue daisy-like flowers with yellow centers that bloom late August into October. The foliage is narrow creating a fine texture. The gray-green color is pleasing all summer and no powdery mildew was reported. Evaluators rated the foliage as good and praised it for its lack of disease issues. It is also aromatic when touched. In all but one site, this aster was not browsed by deer or rabbits.
Veronica longifolia ‘Eveline’ 
Eveline speedwell blooms mid to late summer with some re-bloom in September. The flowers are pink-purple on a tapering four-inch spike. Repeat bloom is more consistent when spent flowers are deadheaded. Dark green, disease-resistant foliage stays shiny and clean late into the season. There is no significant fall color.
Veronica ‘Purpleicious’ Veronica ‘Purpleicious’ is an erect, bushy, clump-forming spike speedwell that is noted for its long period of bloom. Flowers were given high marks for repeat bloom. Evaluators characterized its flower color as a purple-pink, jewel-toned violet and rich pink-violet. Peak bloom took place in June-July, but some flowers were still present in September.
Viola ‘Purple Showers’ ‘Purple Showers’ viola is touted for its large, dark purple flowers that appear from spring through fall atop compact foliage. Lightly fragrant, deep purple-violet flowers appear in spring and then sporadically throughout the season, providing a soft show of color. The flowers fade to lavender. Although flowering in one trial garden (full sun and well-drained soil) was prolific, the May flowering was sporadic in the other gardens.
