Beautiful Mutants

by | Sep 24, 2017 | Native Plants

Fasciated black-eyed Susan, Rudebeckia hirta, by Jon Merz

Fasciation in the inflorescence of a black-eyed Susan (Rudebeckia hirta). PHOTO Jon Merz


We’ve all heard the saying “Two heads are better than one.” If you’ve ever come across a fasciated flower head, which looks like the blossom equivalent of conjoined twins, you might very well agree. If not categorically “better,” these fused-looking flowers and stems are certainly eye-catching and sure to incite curiosity.

So, what is fasciation? Put simply, it’s what happens when open-ended plant cells choose the road less traveled.

Plants have special cells (called meristematic cells) that can develop into any type of plant part, including leaves, stems or flowers, depending on their location in a growing plant. In the case of fasciation, these cells develop as flattened rather than cylindrical growths (hence the name, which derives from “fascia,” Latin for “bandage” or “ribbon”). This can cause broadened stems or, if the fasciation begins in the central whorl of a flower, a spread out, side-by-side development of carpels, stamens, petals and sepals, giving flowers a two-headed look.

Dr. Orland E. White, former director of the University of Virginia’s arboretum, likens fasciation — also known as cristation — to cancer in that it refers to “unregulated and disorganized tissue growth.” But, unlike cancer, fasciation is often considered desirable. Like the plant equivalents of X-Men, these genetic mutants are often looked at as “super-plants.” In fact, fasciated blossoms and stems are beloved and intentionally cultivated for the very virtue of their weirdness. It’s a trait that has been bred into plants by florists or horticulturists looking to maximize blooms in mallows, foxgloves and celosia, for instance, while the wide, at fasciated stems of willows, ferns or Culver’s root (Veronicastrum virginicum) add an unusual look to flower arrangements.

Grafting or cutting is the usual means of propagating fasciated plants, according to Dr. Gerald Klingaman, professor emeritus of horticulture at the University of Arkansas. Klingaman says abnormal growth may be caused by a “permanent change in the genome … possibly triggered by a phytoplasma infection at some point in the distant past,” what he calls a “case of natural genetic engineering.” Other explanations include trauma prompted by insects, disease, physical damage, crowding, extreme temperatures, radiation or chemicals. Seattle-area master gardener Wendy Lagozzino says, “Everything from weeds to trees will produce this unusual growth given the right circumstances.”

While all sorts of plants exhibit the trait, Susan Mahr, coordinator for the University of Wisconsin–Extension’s master gardener program, notes that fasciation is most noticeable in stems and inflorescence, or the flowering parts of a plant. Wildflower Center staff has seen the phenomenon in numerous native Central Texas plants, especially those in the families Asteraceae — particularly Gaillardia spp. and purple and giant cone flowers (Echinacea and Rudbeckia spp., respectively) — and Fabaceae, which includes Texas mountain laurel (Sophora secundiflora). Cacti are also likely to exhibit fasciation, a trait which Mahr says is particularly coveted because the alterations can become “so dramatic that the resulting cactus plant loses almost all resemblance to the original species.”

The Center’s native plant database coordinator, Joe Marcus, says we get “lots of pictures and questions” about fasciation; Texans have spotted the phenomenon in everything from Texas bluebonnets (Lupinus texensis) and black-eyed Susans (Rudbeckia hirta) to various species of Lantana and Dasylirion.

Regardless of where you live, keep an eye out for these unique plants and prepare to be both fascinated and enamored. After all, differences are what make life interesting — and beautiful.