- "What is a Goldenrod?" She Asked
She's smart, a young teenager, a suburbanite. I said, it must be nice to have these hedgerows around your house, full of goldenrods.
"What is a goldenrod?" she asked.
I paled, not knowing where to begin, taken back by her lack of even the basic natural history of her homestead. She had studied biology in school, so knows DNA fundamentals, organ systems in mammals, the basics of cell structure, but not this, the name of the most common showy wildflowers in her community.
But what is a goldenrod, really? What first principles are the best to communicate to a questioning public, naïve to the basic elements of restoration ecology, the rationale and actions to establish even familiar members of the local biota?
Goldenrods are almost too common to be appreciated. About 80 species of Solidago are in North America, found in habitats from shaded forest to dry, rocky hillsides to salty breeze swept seashores. The genus is holarctic, with some species in Europe and China. A few of our North American species are now invasive in Asia, a biotic quid pro quo for the many Asian invasive plants they've given to us. Ranges keep growing and changing. One coastal species, Solidago sempervirens (seaside goldenrod) has migrated inland along roadsides, preadapted to the salt-laden fringes of roads that are treated with salt to melt the winter's ice. They have responded to our use and modification of the landscape and have run away from the shore just as people love coming to the shore. A few Solidago plants are white-flowered, silverrods, not the buttery yellow of their congeners. Hard to tell apart in their morphological similarity, goldenrods are deliciously complex in their ecological personalities. What facets of these personalities should we start with, to introduce them to the curious novice?
Long-lived perennials with wind-dispersed seeds and generalist composite flowers that attract so many insect groups, many goldenrod species can quickly invade open land, pass through juvenile growth stages, and start dominating old fields, the bright yellow display for so many fall habitats. Many species are clonal and can produce dozens of ramets each year, quickly forming wide clusters of connected stems, dominating the local landscape. Count the stems, a dozen, three dozen, but they are one plant genetically, not separate progeny of many seed germinations. We all learn, from childhood, that plants come from seeds; should we tell our curious teenager that most of the stems in her yard are asexually derived? Will we lose her with this first nerdy restoration comment before she is entrained to the wonderful natural history of this wildflower group?
Restorationists are well aware that this clonal growth dominates meadow development. Careful studies show that after six years most stems of S. canadensis are clonally derived. Adding seed to an establishing stand, even one or two years after the initial establishment period, doesn't add many new stems at all. In a botanical version of the early bird gets the worm, the early wildflower gets the soil and sun resources. "Priority effects" we call it, the greedy and grabby behavior of many first arrivals in a restoration project.
These big populations of goldenrods can mask micro-evolutionary adaptations to small-scale stress gradients. Studies of the seaside goldenrod growing on dunes near the ocean show specific adaptations to the salty-wind environment. Populations of these primary dunes are much less damaged by salt deposition on their leaves than are plants from populations 0.5 km inland, near the more protected inland bays (Cartica and Quinn 1980). The species is in fact a rich mix of ecotypes and variants that bedevil the restorationist's toolbox and are completely invisible to nature lovers who use a single drawing of a species in a field guide, as if all individuals come from one adaptive cookie cutter.
Wandering through a patch of goldenrods, our young student might see some stems with hard round swellings, the galls created by ovipositing flies. Other insects make different shaped stem galls. The gall growth affects different components of the goldenrod's performance and reproduction, and the insects are...