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U.S. Forest Service

Plant of the Week

Silene regia Sims range map. Silene regia Sims range map. USDA PLANTS Database.

Silene regia Sims flowers Royal Catchfly (Silene regia Sims) Lizard Head Trail, Colorado. Photo © William Glass.

Royal Catchfly (Silene regia)

By Eric Ulaszek, Horticulturist, Midewin National Tallgrass Prairie

Royal Catchfly is a perennial forb that grows from a perennial crown atop a deep taproot. As the crown grows in size, there may be several rosettes and shoots, but Royal Catchfly does not produce horizontal rhizomes. The stems produced from the crown mat reach up to 1.6 meters tall, sometimes nearly 2 meters, if one includes the inflorescence. The leaves are entire and opposite, up to 7 centimeters long. Royal Catchfly plants may be smooth but more often have a covering of very short hairs; the stems and leaves are usually green, but sometimes the stems develop a purplish tinge. The inflorescence develops at the top of the stem, usually in June. Plants flower from late June to August, but may not start flowering until July at the northern margin of their range. The sepals are green (sometimes covered with sticky glands) and the petals are usually an intense shade of crimson. Sometimes they may be a dull red, very rarely pinkish, or even white. The stigmas and anthers develop at different times, preventing any given flower from self-pollination. The fruit is a capsule, opening at the top. The capsules begin ripening in late August, and most seed falls in September and October. The seeds disperse as the stems holding the capsules are shaken by the wind. Seedlings require an open soil surface for germination and establishment, as would be present after a prairie fire.

Royal Catchfly is widespread in central Midwest, ranging from northern Arkansas, southern Missouri, northern Illinois, northern Indiana, and Ohio south to Alabama and northern Florida. To the west, Royal Catchfly reaches eastern Kansas and Oklahoma. Although widespread, Royal Catchfly is nowhere numerous; it is patchily distributed throughout this broad range. Royal Catchfly has been extirpated from several states, and is considered ‘Endangered’ or ‘Threatened’ by most states within its range. Royal catchfly occurs in prairies, savannas, barrens, and open woodlands, usually on well-drained, often rocky soils. The conversion of these habitats to agricultural use is a primary cause of decline. Many surviving populations are vulnerable to encroachment by invasive shrubs. Like other prairie plants, Royal Catchfly will sometimes persist in roadsides or around the edges of pioneer cemeteries.

Royal Catchfly is one of a small number of red-flowered plants native to the Midwest, and one of very few, red-flowered, prairie plants. The flower shape and color are typical of plants pollinated by hummingbirds. Royal Catchfly is one of the very few prairie plants pollinated by hummingbirds. Only one species of hummingbird occurs regularly within the range of Royal Catchfly – the ruby-throated hummingbird (Archilochus colubris). Hummingbirds are very effective at carrying pollen between subpopulations of royal catchfly, thus the birds’ presence helps maintain genetic diversity of this declining wildflower.

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