Plant Evaluation Notes an Evaluation Study of Tricyrtis Richard G
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Issue 16, 2001 Plant Evaluation Notes An Evaluation Study of Tricyrtis Richard G. Hawke, Manager of Plant Evaluation Programs he subtle blossoms of Tricyrtis, or toad three outer tepals. The tepals usually form an and hybrids being introduced from Japan and lily, bloom in late summer and autumn, upward- or downward-facing funnel, and the United States, including forms with var- Ta time of year when color is rare in pouch-like appendages are located at the base iegated foliage and dwarf habits. Many are shade and woodland gardens. Uncommon of each outer tepal. available only from specialty nurseries, or beauty, late-season blooms and adaptability to Toad lilies are perfect plants for moist in limited quantities, but several species shade give the toad lilies exceptional garden woodlands or shady gardens. In cultivation, have become common in garden centers and merit. they grow best in a moist, humus-rich soil, in nurseries everywhere. Tricyrtis is no longer a There are 16 herbaceous perennial light to moderate shade. Foliage may scorch botanical curiosity or specialty plant, but is species of Tricyrtis, native from the eastern in full sun, but plants will tolerate more sun- recognized as an outstanding perennial for Himalayas to China, Japan, Taiwan and the light if given adequate soil moisture. Leaves late-season interest in shade and woodland Philippines, growing in tall grass near the edge emerge in late spring, usually avoiding frost, gardens. but flowers and leaves can be damaged by of mountain woodlands or in damp, shady The Evaluation Project early autumn frost. The flowers open late in ravines. Toad lilies have vertical to slightly The Chicago Botanic Garden (USDA the season when many other perennials, espe- arched stems, and most spread by creeping rhi- Hardiness Zone 5b, AHS Plant Heat-Zone 5) cially woodland species, have finished flow- zomes. Leaves vary by species and can be conducted an evaluation study of 24 taxa of ering for the year. The flowers are produced lance- to egg-shaped, hairy to hairless, con- Tricyrtis from 1990 to 1999, although not all for a long period and, if unharmed by killing colorous or mottled, and with or without a taxa were grown for the full 10 years. The ini- frosts, will continue blooming into November. clasping base that surrounds the stem. The tial evaluation group contained plants that Garden companions include hosta, fern, helle- white or yellow flowers are borne in terminal were readily available in 1990, with addition- bore, astilbe, Solomon’s seal and rodgersia. and/or axillary clusters, and typically begin al taxa incorporated periodically during the Until recently, toad lilies were neither blooming in early autumn. Flowers may term of the project. common nor well known in the horticultural appear lavender or purple rather than white Due to the unavailability of research world. Few gardening references included due to the degree of purple blotching on the information on Tricyrtis, not much was known information on more than a species or two, and tepals, the segments of a flower that cannot be about the cultivation of toad lilies in the historically, nurseries offered only a limited distinguished as a petal or sepal. Like other Chicago area. The degree of winter hardiness number of species for sale. Today, however, members of the Lily family, or Liliaceae, was an uncertainty, and the particulars of dis- toad lilies are experiencing an explosion in the Tricyrtis flowers are composed of mostly eases and pests that afflicted toad lilies were horticultural market, with many new cultivars equal-sized segments, three inner tepals and unknown. A comprehensive evaluation of the toad lilies was undertaken, with winter hardi- ness of primary consideration. Each taxon was evaluated on five criteria: 1) floral display, Jenny Lee Jenny including flower color, flower size, flower pro- duction and bloom period; 2) habit display, including height measurements, spreading potential, foliage quality and habit quality; 3) winter hardiness; 4) cultural adaptability; and 5) disease and pest resistance. Plant traits and evaluation specifics for the taxa that complet- ed more than four years of the trial are shown in Table 1. A summary rating was assigned to each taxon based on flower production, habit quality, plant health, winter injury and disease or pest problems. A five-star rating signifies an exceptional performance, whereas a one- star rating indicates a very poor performance. Although 24 taxa were evaluated in the 10-year project, only 16 taxa successfully completed four or more years of testing. Four Tricyrtis latifolia 2 Plant Evaluation Notes taxa were eliminated from the project in 1995 was well-drained and periodically droughty, green spots, and the flowers of ‘Kohaku’ were after being verified as taxonomically identical and had an average pH of 7.5 throughout the the largest and showiest of all. to plants already under evaluation. The char- evaluation term. Flowers are borne at the terminals and/or acteristics of Tricyrtis dilatata were verified Maintenance practices were kept to a in the upper leaf axils of most species. The as identical to the synonymous species T. minimum to simulate home garden culture. Tricyrtis hirta cultivars produced clusters of macropoda. No differences in characteristics Overhead sprinklers provided water as needed, large, showy flowers in the leaf axils along the were observed between the plants of T. for- and no fertilizer was applied. An 18-inch-high entire stem, a trait that created a more impres- mosana var. stolonifera and T. formosana, the wire mesh fence, to deter rabbits from eating sive floral display than on other species. former considered a synonym of the latter the plants, enclosed the plot beginning in the Flower coverage at peak bloom—usually two (Mathew 1985). Plants received from third season. A mulch consisting of shredded to three weeks after the first flowers opened— Heronswood Nursery as T. maculata closely leaves and wood chips was placed around the was typically under 40% on most species, but matched the characteristics of T. formosana, plants for aesthetic purposes, water conserva- long bloom periods compensated for the low and were subsequently purported to be a tion and weed suppression. coverage. Tricyrtis formosana and T. hirta hybrid between T. formosana and T. hirta, ‘Miyazaki’ had the best floral show with more Observations according to plantsman Dan Hinkley of than 80% of the flowers open at once. Floral, foliar and habit traits were Heronswood Nursery. All plants received as Most of the toad lilies had green leaves, observed and compared for each toad lily dur- Tricyrtis ‘T&M Hybrids’ proved to be T. hirta although a number of cultivars displayed var- ing the growing season. The flowers are typi- and were removed from evaluation. In addi- iegated or chartreuse foliage. The strongest cally upward-facing, funnelform and white or tion, four taxa including Tricyrtis hirta variegation was the creamy-white margins of yellow with purple or maroon spotting. The ‘Golden Gleam’, T. formosana ‘Amethystina’, Tricyrtis hirta ‘Albomarginata’. The soft yel- pendulous, tubular flowers of Tricyrtis T. ‘White Flame’ and T. ‘Adbane’ died within low margins of T. hirta ‘Miyazaki Gold’ and T. macranthopsis are a clear yellow with reddish- the first or second year, but were not replaced hirta ‘Variegata’ were similar, but more pro- brown spotting inside, and easily distinguished for further testing. nounced on the former and faded to lighter from other toad lilies. The flowers of T. The test site featured two mature red oaks green by the late season on the latter. The char- macropoda are unique among the toad lilies that provided natural shade for the majority of treuse leaves of ‘Lemon Lime’ were marked because the tepals are fully reflexed at maturi- the toad lilies. The site received morning sun with small green spots, and the large, lush, ty, resulting in one of the smallest flowers. The for several hours, but was in medium dappled spring-green leaves of ‘Tojen’ nicely comple- flowers of ‘Tojen’ are distinct from other toad shade for the remainder of the day. Only mented its handsome burgundy stems. lilies—the outer tepals are white with laven- Tricyrtis hirta ‘Miyazaki’ received full mid- Tricyrtis formosana had the darkest green der margins and the inner tepals are clear day sun during the summer months. All plants leaves, and T. macranthopsis was the only toad white, without spotting. The white flowers of were sheltered from wind by wooden fences lily with glossy foliage. The elliptic- to ovate- T. hirta ‘Alba’ are actually marked with pale that surrounded the garden. The clay-loam soil shaped leaves of Tricyrtis latifolia and Table 1: Plant Characteristics and Performance Summary Ratings Overall Tricyrtis Flower Flower Flower Bloom Plant Plant Habit Anthracnose Rating Color 1 Size Coverage 2 Period Height Levels 3 ★★★★★ Tricyrtis formosana white, dark purple 11/4 - 11/2 in. high late Aug-early Nov 36-40 in. upright stems none ★★★★ Tricyrtis hirta white, pale purple 1- 11/2 in. moderate early Oct-mid Nov 24-36 in. arched stems minor,1995-99 ★★★ Tricyrtis hirta ‘Alba’ white, pale green 1- 11/4 in. moderate mid Sep-late Oct 36-40 in. arched stems minor to severe,1995-99 ★★★ Tricyrtis hirta ‘Albomarginata’ white, purple 11/2 in. low late Sep-mid Nov 20-27 in. arched stems minor to severe,1996-99 ★★★ Tricyrtis hirta var. masamunei white, purple 11/4 in. low early Sep-early Nov 16-24 in. arched stems minor,1998-99 ★★★★★ Tricyrtis hirta ‘Miyazaki’ white, pale purple 11/2 - 13/4 in. high late Sep-early Nov 24-30 in. arched stems none ★★★★ Tricyrtis hirta ‘Miyazaki Gold’ white, pale purple 11/2 in. low late Sep-early Nov 18-24 in. arched stems minor,1995-99 ★★★★ Tricyrtis hirta ‘Variegata’ white, pale purple 1- 11/2 in.