Silene, like their close relatives Lychnis, are commonly known as campion or catchfly. The genus Silene and Lychnis have often been interchanged over the years. Botanically, they are separated based on subtle differences in their floral structure. Generally, Silene have 3 styles and capsules that open with 6 teeth while Lychnis have 5 styles and capsules with 5 teeth. Most of us are more interested in how they can be used in our gardens!
Like Lychnis, most Silene are found in the northern hemisphere but a few do occur in South America and Africa. There are nearly 500 species of Silene (compared to only about 20 Lychnis) but where most Lychnis are garden-worthy plants, many of the Silene are rather weedy. In fact, some are considered invasive. The greatest diversity of species occurs in the Mediterranean region.
Silene vary greatly in size and habitats. There are many choice alpine species, but others occurs in meadow or woodland settings. Species include both annuals and perennials, although most perennial types are rather short-lived. However, some perennial alpine species are notable exceptions.
First a look at the sun-loving, annual species. There are several species commonly cultivated as annuals. Silene armeria is among the most popular with wiry stems to 40 cm and small heads of brilliant pink flowers that contrast with blue-tinted foliage. Silene compacta is a more dwarf version. Silene mexicana is another S. armeria look-alike but can be a short-lived perennial in warm areas. Silene coeli-rosa is another popular annual species with many named selections available in a mix of white, pink, red and purple shades. Perhaps the best annual species is S. pendula which is more compact and floriferous than the previous annual species noted. This latter species also has a number of named cultivars, some which are double-flowered.
Examples of annual Silene include S. armeria and S. coeli-rosa
A traditional flower of European cottage gardens was and still is, the red campion (S. dioica) and white campion (S. alba or S. latifolia). Both are short-lived perennials and prefer some afternoon shade. They self-seed with abandon and should be used with care. Prompt deadheading will keep them tame and help extend their life. The former have numerous carmine-pink flowers on plants reaching 80 cm while the later is much like a white-flowered version. Hybrids between the two exist with light pink flowers. Longer-lived and more elegant is the fringed campion, S. fimbriata, which reaches 60 cm with white, fringed flowers and a rounded, swollen calyx. These are all rated hardy to zone 3-4.
The two most common and perhaps weedy species are S. dioica and S. latifolia (S. alba)
To attract hummingbirds and butterflies, you need to grow the flaming orange to red species. Alas, these stunning species are short-lived and rather tender compared to most Silene (zone 6 and milder). Among these are S. laciniata ‘Jack Flash', S. californica, S. regia and S. virginica. The latter species is the longest-lived and hardiest, suitable to zone 5. It also prefers some shade compared to the other red-flowered species.
Among the red species are S. laciniata (top left), S. californica (top right), S. regia (lower left) and S. virginica (lower right)
The remaining notable species are all alpines or of small enough stature to be used mostly in rock garden settings. The most dwarf of all is the moss campion, S. acaulis (zone 1!), a tight bun of mountain and Arctic regions of the northern hemisphere. While very choice, this one is difficult to grow in warm-summer areas. A similar, larger-flowered version of S. acaulis is S. davidii. More amenable is sea campion, S. uniflora (aka S. maritima) which forms a small mat of blue to grey-green foliage and white flowers with an inflated calyx (zone 3). The variegated cultivar 'Druett's Variegated' has particularly striking foliage. Silene falcata looks much like a smaller version of S. uniflora. Among the more tender alpine species are S. argaea and S. hookeri (zone 5-6). Both have bright pink flowers but the latter species has the added bonus of white-felted foliage. These species perform best in regions with drier winters. For late season blooms in the rockery (Sept-Oct) try S. schafta or S. keiskei, Asian species with bright pink flowers on 20 cm stems (zone 5-6). Another choice alpine is Heliosperma alpestre, once known as Silene alpestris. This long-lived species produced a mat of dark green foliage and masses of small white flowers.
The most dwarf Silene are S. acaulis and S. davidii (right)
Silene uniflora and the variegated cultivar called 'Druett's Variegated'
Other dwarf Silene include S. argaea and S. hookeri
Heliosperma alpestre was once considered Silene alpestris
This is not an exhaustive list of the cultivated Silene. More alpine species seem to be introduced each year as botanists further explore the Himalayas and southern and eastern regions of the former USSR. It does, however, introduce you to the diversity that exists among the campions and catchflies. Next we will cover another group of close relatives, the genus Saponaria, known as the soapworts.
I would like to thank the following people for the use of their photos: altagardener (S. davidii), begoniacrazii (S. uniflora 'Druett's Variegated'), dmj1218 (S. regia), Kell (S. laciniata), kniphofia (S. latifolia), poppysue (S. coeli-rosa, S. armeria), Toxicodendron (S. virginica), Sally_Denver (S. argaea) and trilian (S. dioica)