Being called a frog isn’t exactly a compliment. The amphibious creature we all know has warty skin that can secrete poison. Calling someone a toad means they are contemptible or hateful, according to the Oxford Dictionary.
Does this definition apply to plants as well? Plants of the genus Tricyrtis are often called toadstools. The most common explanation for the name frog is that the flowers and leaves are spotted like frogs. Also, the flowers have warty, sac-like protuberances at the base of the flowers that some believe mimic the skin of a frog. These protrusions are known as nectaries, and in my opinion they are a far cry from the appearance of frog skin.
I personally like the Japanese name for Tricyrtis, hototogisu, which is the name of a shy bird that lives in the forest. Even the “lily” part of the common name is a bit misleading. Tricyrtis belongs to the Liliaceae, the lily family, but true lilies belong to the genus Lilium. Tricyrtis may be shy, but it is an asset in the fall garden.
Frog plants are shade-loving herbaceous perennials, native to the Himalayas to East Asia, including China, Japan, Taiwan and the Philippines. They are found on shady rocky slopes, river banks and along forest edges. Tricyrtis is almost always found where rainfall is abundant, although I have found that it is quite drought tolerant once established.
The genus consists of about 20 species, but most plants in commerce are either Tricyrtis formosana or Tricyrtis hirta, or hybrids of the two. Other species may not be as hardy in Wisconsin.
Tricyrtis hirta, the hairy frog, is the coldest species in this genus. As the name suggests, the leaves are hairy, arranged in a ladder shape along the unbranched stems. It spreads slowly to form a mass.
The flowers have a white or pale purple background color and are covered with dark purple spots and blotches. They are between 1 and 1 1/2 inches wide and have the appearance of an orchid. Flowering time is from mid-September to mid-October. Due to the small size of the flower and the detailed colours, it is best used where it can be seen up close. The hairy frog ranges in height from 1 to 3 feet.
Tricyrtis formosana, Formosa toadlily, is not as hardy as Tricyrtis hirta, but it hybridizes with it easily, resulting in several cultivars that are reliably hardy in southern Wisconsin.
Unlike the hairy lily, it spreads with lateral stems to form a colony, but not so quickly as to become invasive. The flowers bloom over a longer period of time than Tricyrtis hirta, usually continuing until a severe frost stops flower production.
While purple is the natural flower color, Tricyrtis macrantha is a species with yellow flowers. Unfortunately, they are only hardy to zone 6, making them less reliable even in southeastern Wisconsin. If you can grow it in a protected area, the gorgeous flowers make it worth a try.
I grow five varieties of Tricyrtis in my garden. Tricyrtis ‘Miyazaki’ grows about 18 inches tall and has purple flowers with white spots. It is highly flowering and was the top choice in trials conducted at the Chicago Botanic Garden.
Some list it as a cultivar of Tricyrtis hirta, while others consider it a hybrid with Tricyrtis formosana. ‘Blue Wonder’ is a hybrid with light purple flowers with dark purple spots.
Tricyrtis ‘Tojen’, another hybrid, has larger leaves than the typical toad lily. Lavender orchid flowers are mostly terminal, not in the leaf axils, and unspotted. The bright green leaves contrast with burgundy stems.
‘Lightning Strike’ has golden foliage streaked with green. Lavender flowers are produced at the top of stems that are 2 feet tall. My most recent acquisition is Tricyrits formosana ‘Autumn Glow’. A broad yellow margin on the dark green leaves makes it distinctive in the garden.
The variety I don’t grow, but have admired in other locations, is ‘White Lightening’, a cultivar of Tricyrtis hirta. It is a vigorous, upright grower and has a pure white flower along the stems in the leaf axils. White flowers are a beacon in the shade garden. Toadlily is a wonderful companion for hostas, ferns, astilbe, hellebores, heuchera and spring-blooming wildflowers. It is resistant to deer browsing, but rabbits may find new shoots to their liking.
For a fall flowering shade plant, it can’t be beat.
Cedarburg resident Glen Herold was a professor of horticulture at Central Illinois College, East Peoria, Illinois from 1979 to 2011. He earned a bachelor’s degree in biology and a master’s degree in horticulture from the University of Wisconsin-Madison. He currently holds membership in the Midwest Regional Hosta Association, American Hosta Association, American Conifer Society, Maple Society, Wisconsin Woody Plant Society, and Wisconsin Hardy Plant Society. Anyone with questions or comments can email Glenn at PlantmanGlenn@gmail.com. Additional articles on plants and gardening can be found on my blog: https://TheCottageGardener53012.Wordpress.com.