Foliage clumps resemble those of columbine (Aquilegia). Plants typically bloom in late spring or summer, sending up sparsely leafed stems topped by puffs of small flowers, each consisting of four sepals and a prominent cluster of stamens. Superb for airy effect; offer a pleasing contrast to sturdier perennials. Delicate tracery of leaves and flowers is particularly effective against dark green background. Foliage is good in arrangements. Most meadow rues need some winter chill; all thrive in dappled sunlight at woodland edges. Protect from wind. Divide clumps every 4 or 5 years. Deer resistant.
T. aquilegiifolium. COLUMBINE MEADOW RUE. Zones US, MS, LS; USDA 6-8. From Europe, northern Asia. To 23 ft. tall, 1 ft. wide, with bluish green foliage. Earliest of the meadow rues to bloom: Clouds of fluffy stamens (the white or greenish sepals drop off) appear for a couple of weeks in mid- to late spring. Rosy lilac is the usual color, but white and purple selections are available. If left in place, spent flowers are followed by attractive, long-lasting seed heads. Heat tolerant. 'Thundercloud' is a vigorous, heavy-blooming variety with deep rose-purple stamens. 'Album' has white stamens; those of 'Purpureum' are pinkish purple.
T. 'Black Stockings'. Zones US, MS, LS, CS; USDA 6-9. Hybrid of uncertain parentage. Resembles T. rochebrunianum, but with sturdy black stems.
T. delavayi (T. dipterocarpum). CHINESE MEADOW RUE. Zones US, MS, LS; USDA 6-8. From western China. To 34 ft. (even 6 ft.) tall, 1122 ft. wide, with thin, dark purple stems that need support. Green foliage. Violet to lavender sepals, yellow stamens. 'Album' has white sepals. 'Hewitt's Double' sports double lilac-colored flowers (one row of sepals, another of modified stamens that resemble petals); bloom continues for two months or longer. Heat tolerant.
T. flavum. YELLOW MEADOW RUE. Zones US, MS, LS, CS; USDA 6-9. Native from Europe to the Caucasus and Siberia. Heat-tolerant, green-foliaged species to 35 ft. tall, 1122 ft. wide; stems need staking. Blooms in summer, bearing flowers like those of T. aquilegiifolium, but in lemon-yellow. Leaves of 'Illuminator' emerge yellow-green, then turn bright green. T. f. glaucum (T. speciosissimum), called dusty meadow rue, has blue-green leaves and stems; its selection 'True Blue' is an improved, sturdier plant.
T. kiusianum. DWARF MEADOW RUE. Zones US, MS, LS; USDA 6-8. From Japan. Bluish green leaves; plant spreads to form mats of tidy rosettes, each to 6 in. high and wide. Light purple, 12-in. blooms rise just above the foliage in late spring or early summer. Excellent in rock gardens or along paths.
T. rochebrunianum. Zones US, MS, LS, CS; USDA 6-9. From Japan. To 46 ft. tall, 1122 ft. wide, with sturdy stems that don't need staking. Flowers consist of white or lavender sepals and pale yellow stamens. 'Lavender Mist', with violet sepals, is a superior selection.