(Editor's Note: this article was originally published on August 23, 2008. Your comments are welcome, but please be aware that authors of previously published articles may not be able to promptly respond to new questions or comments.)
Perhaps the most elegant of the spring-flowering bulbs are the trout lily, fawn lily, glacier lily or dog's-tooth violet, also known as Erythronium. The flowers of most are nodding, with reflexed petals, looking decidedly like turk's-cap lilies. The flowers may be solitary or several per stem, varying in height from a few centimetres to about 30 cm. Floral colours vary from white to yellow and pink shades. The leaves are smooth, broad or narrow and held close to the ground. They may be solitary or produced in a cluster. Many are attractively mottled with maroon spots and blotches. Most are hardy to zone 3 if properly mulched.
These lily relatives hail primarily from North America with just a single species being found in Europe and two species in Asia. The name comes from erythros, Latin for red, referring to the reddish-pink flower colour of the European species E. dens-canis. In this example, the species epithet dens-canis means dog-tooth, referring to the shape of the bulb. The North American common names trout or fawn lily refers to the mottled foliage of many of the species. Glacier lily refers primarily to the high alpine species that bloom just as the snows melt.
Worldwide, there are some 20 species of Erythronium, although as garden ornamentals, we only grow a few. All are spring-blooming bulbs that often start to bloom shortly after the snow melts, especially those which hail from high mountainous areas. Depending on where you live, they may bloom from late February to late June. In the wild, they either grow in lightly shaded woodland areas or from sunny, alpine meadows. Most prefer even moisture year-round but a few of the high alpine species, such as E. grandiflorum, E. helenae and E. hendersonii, require perfect drainage and drier conditions during the dormant season. As it happens, these species are among the most difficult to grow in cultivation due to their exacting requirements.
The bulbs of all the species are distinctly tooth-like in shape. They lack the protective skin found on tulips, daffodils and most of the other fall planted-spring blooming bulbs. As a result, the bulbs of Erythronium cannot hold moisture for long once out of the ground. When you purchase them, plant them immediately. A few are offered in local nurseries but most are available only at specialist bulb nurseries. For the adventurous, you may grow them from seeds sown in fall, but be patient as it may take 5 years or more to reaching blooming-size.
The European species, E. dens-canis has solitary flowers in various shades of pink with very attractive mottled foliage. It is one of the earliest-blooming species and also among the shortest.. There are several named forms which vary in their shades of pink as well as several white-flowered selections. Erythronium caucasicum is very similar with white flowers and considered by some to be merely a variant of E. dens-canis.
The dog's-tooth violet, E. dens-canis
One of the easiest American species is E. americanum. This is also a small species with solitary flowers, in this case bright yellow with various brown spots. The foliage is perhaps the most striking of all the Erythronium. This species produces underground stolons which run, resulting in new plants popping up some distance away from the parent bulb.
The American trout lily, E. americanum
The largest and most prolific are the hybrids and or selections (the jury is still out!) derived from E. tuolumnense, E. californicum and E. revolutum, all which hail from the mountains of California. These hybrids may reach to 30-40 cm, with 3-5 flowers per stem and relatively large basal leaves which are variously mottled. The most popular and vigorous hybrid is probably ‘Pagoda' with pale sulfur-yellow flowers. ‘Citronella' has smaller blooms of bright lemon-yellow. ‘Pink Beauty' and ‘White Beauty' are pink and white-flowered respectively.
Some of the named selections include 'Pagoda', 'Citronella' amd 'White Beauty'
Other species which may be offered in the trade include E. albidum, an eastern North American species with solitary, white flowers and mottled leaves. From western North America comes the difficult alpine species E. grandiflorum, E. helenae, E. montanum and E. hendersonii. Westerners more amenable to cultivation include E. oregonum (1-3 white flowers, mottled foliage), E. californicum (1-3 cream white flowers, mottled foliage), E. howellii (nearly identical to E. californicum), E. citrinum (essentially a yellow-flowered E. californicum) and the parents of the hybrids, E. tuolumnense (solitary yellow flowers, plain green foliage) and E. revolutum (1-3 pink flowers, mottled foliage).
Some other American species inlcude E. albidum, E. revolutum and E. oregonum
To round out the list there are two Asian species of note. Erythronium japonicum has solitary lilac-purple flowers with darker interior markings and striking mottled foliage. Some gardeners consider this species the most beautiful of all the Erythronium. Finally there is E. sibericum, a plain-foliaged species whose relatively large soliatry flowers are pink with a contrasting cream-white center.
Flower and foliage details of E. japonicum
Now that we are starting to think about which fall-planted bulbs we will grow this year, keep Erythronium in mind. For the woodland garden and rock garden, they are second-to-none for their elegance and graceful beauty.
I would like to thank the following people for the use of their pictures: Galanthophile - E. revolutum; GardenGuyKin - E. oregonum; Jeff_Beck - E. albidum.