Pollination syndromes

by Bryan Fischer, Horticulturist, Gardens on Spring Creek

Flowers have evolved in a dizzying array of shapes, sizes, colors and arrangements since they first made waves on the evolutionary scene at least 120 million years ago. In most cases, this enormous diffusion of morphology owes its existence to the interaction between pollinators and plants. The more effectively a given animal pollinates a plant, the more that plant species will adapt over time to favor pollination by that animal.

These adaptations are predictable depending on the type of pollinator and are sometimes called “pollination syndromes”. If you’re looking to attract a specific type of insect or other animal to your garden, having a general understanding of these syndromes can be both fun and helpful when shopping at the nursery.

First to evolve, and perhaps the least flashy, beetle-pollinated flowers bear cup-like shapes (think magnolia) and are usually creamy or white in color with varying degrees of fragrance. These cup-shaped crash pads provide an easy place to land and a protein-rich meal in the form of pollen for the beetles, which can be a bit of a nuisance in flight.

With skillful vision and attunement to colors (with the exception of red, which they do not perceive), bees benefit from “nectar guides” – lines or dots leading to the flower’s nectar. Flowers suitable for pollination by bees are usually present in yellow, purple, blue or white and bear a flat area that acts as a landing area. Flowers pollinated by bees usually have pollen available, which is a protein-rich food source for these hardworking insects. Interestingly, because bees can perceive ultraviolet radiation, many flowers have evolved features designed to show up under the UV light emitted by the sun. These features are invisible to the naked eye but can be seen under a UV lens. Bee-pollinated species commonly grown in our region include sunflower (Helianthus spp.), asters (Symphyotricha spp.) and lavender (Lavender spp.).

Butterfly-pollinated flowers share a few characteristics with bee-pollinated flowers: nectar guides are common, landing sites are typical, scents are mild and sweet, and colors are bright. Beyond these similarities, butterfly-pollinated flowers produce abundant nectar that sits at the end of a tube – a long, nimble proboscis is almost always required. For local examples, look at the butterfly bush (Buddleja spp.), liatris (liatris spp.) and phlox (Phlox spp.).

Proportioned much like butterfly-pollinated flowers, bird-pollinated plants feature elongated, tubular flowers. This is especially true for New World plants where long-billed hummingbirds are the primary bird pollinators. These plants will often bear sturdy stems to allow occasional use as a perch. Native bird-pollinated plants are often bright red or orange, such as Penstemon Eatonii and hummingbird mint (rock agastache), as these warm colors make them easy to see from a distance for visually-navigating hummingbirds.

A variety of other animals, including bats, moths, and flies, also reliably pollinate plants. However, their pollinator syndromes may make them less appealing to gardeners: flowers pollinated by bats and moths are usually white and bloom at night, as these pollinators are usually nocturnal, and flowers pollinated by flies are usually designed to mimic an animal carcass, with an odor. . So the next time you go to the nursery, think about what animals your plant choices might attract. Just make sure that whichever way you decide to “concrete” you like the front border as well.

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