By late August, the first large swaths of yellow are appearing along roadsides and in fields across the Kawarthas. Goldenrods are coming into bloom, soon to be joined by the purple, mauve and white blossoms of asters. Together, they will dominate the landscape through much of September.

This week, I’d like to take a closer look at goldenrod itself — its fascinating flowers, diverse insect visitors and remarkable galls, along with some of the many species found locally.

Although we talk about a goldenrod “flower,” what we see is actually a collection of many tiny flower heads. Each head is made up of several individual flowers called florets. A single goldenrod plume can therefore hold thousands of flowers, each capable of producing nectar, pollen and eventually a seed.

This arrangement is ideal for insects. A bumblebee, solitary bee or flower fly can land once and walk from floret to floret without having to expend energy repeatedly taking flight. On a warm, sunny afternoon, a large patch of goldenrod can resemble a busy airport, with insects constantly arriving and departing.

Goldenrod is especially valuable because it blooms when many other wildflowers have already finished for the year. Bumblebee colonies are now producing new queens that will mate and, if they survive the winter, establish new colonies next spring. Many solitary bees are still provisioning their nests, while butterflies, beetles, flower flies and wasps also require late-season food.

Honeybees and bumblebees are often the most obvious visitors but look closely and you’ll also see smaller solitary bees. The term describes bees whose females build and provision their own nests rather than living in colonies. Most of Ontario’s more than 400 bee species are solitary, including mining, mason, leafcutter, cellophane and many sweat bees.

Canada........

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