By Lauren Lewis
Flowers are the garden’s showstoppers. Even the least botanically-inclined can appreciate their color and fragrance, and for Valentine’s Day they’re a near requirement as a sign of your love. For the plant itself, the flower allows for reproduction. Most flowers contain both pollen (the male contribution to reproduction) and ovules (like eggs) that accept pollen and turn into seeds. The colorful petals have evolved to attract critters like us, though more accurately insects and birds, who visit the flower and unknowingly carry the pollen to another flower. Plants rely on the beauty of their flowers for their continued existence.
In an urban environment, we can can use our love of flowers for a good cause. You’ve probably seen press about honeybee population decline, which is concerning because of its impact on agriculture, but you may not have heard about the same problem happening among native pollinators (honeybees are originally from Europe). Hundreds of native pollinator species -bees, butterflies, moths, hummingbirds- are threatened by lost habitat, chemical use, and other factors. The good news is that we urban residents have some agency over the survival of those diverse pollinators depending on how we choose to use our open spaces, and especially how we incorporate flowers.
In one study of bees in urban parts of California’s central coast, researchers found that bee diversity and abundance were higher in gardens with more abundant flowers, more plant diversity and more open ground as opposed to mulch. The flowers provide bee food, and the authors theorize that plant diversity and open ground likely provide nesting habitat for varied bee species. The authors found that these garden-level factors were more strongly associated with bee population health than larger scale factors such as how developed the surrounding land is. This finding illustrates the potential power that a garden owner can have in the effort to protect pollinators.
Seattle’s Pollinator Pathway is a fantastic example of people using their power of garden design to support pollinators. Founded by Sarah Bergmann, the Pollinator Pathway is a mile-long, 12 inch-wide stretch of curb gardens planted with plants picked specifically to attract pollinators. It connects a college campus with an urban forest, in an effort to support movement of small pollinators, who often can only fly short distances at a time. Through Sarah’s effort, the owners of these tiny flowered plots collaborated to create something greater than the sum of its parts.
Here in San Francisco we have the Green Hairstreak Corridor, a series of small habitats in the Inner Sunset, intentionally designed to support the Coastal Green Hairstreak butterfly. This Nature in the City project focuses on the single butterfly species, but with the same goal as the Pollinator Pathway of providing a series of habitats that support insect movement, rather than a single oasis of appropriate flowers. This type of effort is inspiring in its ability to bring neighbors together toward a goal that goes beyond the beauty of their individual outdoor spaces.