Since there’s still nothing officially planted in the Rocky Mountain Botanic Gardens (RMBG) yet, it’s a bit early to be talking about what’s blooming, but there are actually lots of flowers–on the weeds.
The bright bulbous blossoms of white campion (Silene latifolia, Pink family, Carophyllaceae) have popped out this week, along the river trail and behind the garden compost pile. This plant is a Eurasian native, introduced and now widespread across North America. In typical weedy fashion, it grows on roadsides, floodplains, disturbed areas, meadows, and cultivated land. The most distinctive part of a white campion flower is the calyx behind the petals, which inflates balloon-like around the developing seed capsule and is decorated with green or purple-red veins. A calyx (plural, calyces) is the structure that protects a flower bud. After a flower opens, the calyx on many species looks like a set of small petal-like leaves or leaf-like petals (known as sepals) at the base of a flower, but the calyx of white campion is prominent and fused into one piece. Each flower has five white petals with deep notches nearly splitting them in half, and there’s a little extra frill of a collar at the flower’s center. The plants are hairy, which makes new leaves soft to the touch, and the calyces, already striking at a distance, look even wilder under a magnifying lens.
In the heat of midday, white campion often looks crumpled. That’s because these flowers bloom at night to attract moths as pollinators. They also release their fragrance at night. Certain other white flowers do this, too, so gardeners sometimes plant collections of fragrant white night-blooming flowers to enjoy after dark. The RMBG Prairie Grasslands garden (slated to be planted first) will include two species of native evening primroses, the prairie evening primrose, Oenothera albicaulis, and the white stemless evening primrose, Oenothera caespitosa. Like white campion, these flowers open in the evening, as their names suggest. Both grow low to the ground with stunning, large white flowers pollinated by night-flying insects.
Up close, white campion flowers don’t all look the same. This species is dioecious–that is, each plant has either male or female flowers. This is one of the mechanisms that has evolved in plants to avoid self-fertilization and excessive inbreeding, increasing the flow of genetic material by requiring two parent plants for every seed. The flowers on male plants have bright clumps of yellow pollen at the center, while female flowers have a cluster of curving white structures to catch the pollen. Only the fruit-bearing female flowers have the ballooning calyces. On males they are still noticeable but don’t puff up. Another dioecious species among local favorites is the rocky mountain juniper (Juniperus scopulorum). Some plants bear juniper berries, while others produce pollen-spewing male cones that give the plants a brownish-yellow look in spring.
White campion is in the Pink family (Caryophyllaceae), named for the flowers called pinks, which are also known as dianthus and often are actually pink. Carnations and Sweet Williams are other cultivated members of this family. Colorado native Pink family species include the prairie mouse-ear, Cerastium arvense, which forms constellations of white flowers under ponderosas in spring, and the pink cushion-forming alpine favorite, moss campion, Sileneacaulis. At first glance, two other Pink family members introduced from Europe can look like white campion. Bladder campion, Silene vulgaris, has even larger bladders (calyces) that lack the dramatic veins of white campion, and bouncingbet or soapwort, Saponariaofficinalis, has petals without the deep notch, a slender calyx, and hairless leaves. Bouncingbet and white campion were both used historically as soap, their roots beaten to a lather for laundry. Keep an eye out for white campion blooming around town all summer long. It’s certainly a plant worth a closer look, but don’t expect to see it (much) in our lovingly weeded native garden beds.
In other garden news this week, our partners at the Town of Lyons have just completed the work for the garden to get irrigation water. Although we’re planning to use as little water as possible, watering will be necessary for establishing young plants. This brings us one step closer to planting!
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To learn more about white campion, take a look here:
Jessie Berta-Thompson has lived just outside of Lyons for four years. She is an enthusiastic volunteer for the Rocky Mountain Botanic Gardens, with experience in biology research and outreach.