Wild Side: Cowpen daisy

They really hit their stride in the fall.

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A syrphid fly in the genus Eristalis, also feeding on cowpen daisy. —Matt Pelikan

When I arrived on the Vineyard in 1997, moving into a relatively new house with conventional landscaping in Oak Bluffs, I knew very little about the Island’s unique ecology. And owning a home for the first time, I had limited notions of how to maintain a yard and garden.

Several years of vigorous, if misguided, management followed. I cut borders and beds, then weeded and edged them religiously. I planted horticultural exotics and struggled to suppress weeds and encourage sod grass on our property’s lean soil, even to the point of watering and fertilizing our pitiful, lumpy lawn a few times.

Before long, I recognized the futility of trying to make land do something it doesn’t want to do. To reduce my workload and to avoid measures that I came to view as ecologically harmful, such as supplemental watering and the application of nutrients or pesticides, I made the profoundly liberating decision to let the plants themselves sort things out.

I stopped mowing, stopped defending the beds and borders, planted species native to the Vineyard, aggressively tackled some of the worst invasives in the yard (Asiatic bittersweet and cat’s ear), but generally just let the property drift toward its own notion of what it should be. The result looks untidy, to say the least. But as regular readers of this column know, I’ve been rewarded with a remarkable wealth of insect life, attracted by the complexity and diversity of the Meadow Formerly Known as the Yard.

One rare exception to this overall strategy was my deliberate introduction of cowpen daisy, Verbesina encelioides, onto the fringes of our small vegetable garden. The plant, an annual native to the Western and Southern states but apparently not to New England or the Vineyard, was recommended to me by a fellow butterfly enthusiast on the Bay State’s North Shore, who kindly sent me a packet of seeds.

Distributed on lightly scuffed bare soil, the seeds germinated well and grew to about four feet tall. Verbesina is optimized for fine-grained, dry, nonacidic soil, but is clearly widely adaptable. While some sources hint that it’s allelopathic — that is, produces chemicals toxic to nearby plants — I’ve seen no evidence of this in my garden, where it coexists politely with a range of species.

I confess to some ambivalence over my use of this plant, and I keep an eye on it accordingly. It has become widely naturalized outside its native range, not just as a garden plant in North America but, through unknown mechanisms, in places as far-flung as Africa and the Hawaiian Islands. A typical adventive species, it is deft at finding and exploiting patches of bare or lightly disturbed ground. Very little seems to eat its gray-green foliage.

Verbesina is viewed as an agricultural pest in some areas (notably, it competes vigorously against peanut crops, reducing yields). It is a full-blown noxious invasive on some Pacific Ocean islands, even to the point of ruining seabird breeding colonies by restricting the access and movements of birds. And it is considered mildly toxic to grazing animals, causing lethargy if eaten in quantity.

In my yard, it has stuck to the fringes of the vegetable plot; in 10 years I’ve never noted it sprouting anywhere else. This plant’s ability to self-fertilize has probably helped sustain my very small population (some years, only two or three plants persist to maturity). But seed viability seems to be declining, so despite its ability to self-fertilize, cowpen daisy may still be susceptible to loss of vigor through inbreeding.

I like this plant’s hardiness and seasonality. Seedlings are sometimes snipped by cutworms early in the season, but most of them rebound. During summer, young verbesina persists even though shaded by tall, early-season species. And in the fall, cowpen daisy hits its stride, shrugging off light frost and producing glowing yellow flowers in abundance into early December most years.

Verbesina is wildly popular with pollinators, in part because it is nearly the only game in town in late autumn. On sunny days, even if the air temperature is only in the 40s, bees and flies flock to flowers, which are about an inch and a half across, with a fuzzy central disk surrounded, in typical aster fashion, by a ring of longer petals. This is what I like most about this plant: It’s a generous resource for insects at a time when little else is available.

I don’t know whether the presence of cowpen daisy translates into greater reproductive success for, say, the native bees that nest in my yard. They may already have completed laying eggs, provisioning their nests with pollen, and sealing up their burrows for the winter.

But I suspect the availability of these golden blossoms at least prolongs the lives of these individual insects, which often cling to the flowers overnight and resume feeding as soon as the sun warms them up the next day. I’m happy to give them a bit more time to carry out their business, and I hope that this extension translates into a few more offspring for the future.