This article was originally written by James Gagliardi and Holly Walker of Smithsonian Gardens, and modified by the MJV.
Pollinators are an essential part of our gardens, the ecosystem, and the United States economy. Honeybee pollination adds more than $15 billion to the value of agricultural crops in the US each year, with another $9 billion coming from pollination by other species. Pollinator populations of all kinds have been declining after decades of stressors related to loss, degradation, and fragmentation of habitat, reduction in the number and quality of food sources, a lack of sites for breeding, nesting, and roosting, and increased use of pesticides and herbicides.
Gardeners can be part of the solution to pollinator loss by creating diverse landscapes that support pollinator health. The Smithsonian Gardens in Washington D.C. are great examples of showcasing pollinators and their plants, as well as educating and encouraging gardeners to do their part!
The Pollinator Syndrome
From butterflies and bees to beetles and birds, many different kinds of pollinators have evolved within their ecosystems, building unique relationships with plants. Therefore, planting a rich diversity of pollinator-friendly plant species supports a wide variety of pollinators. For successful pollination, pollinators need to be in the right location at the right time, and most importantly, have the right body shape and function.
A pollinator must find a flower with a structure that matches their body. Consider a butterfly feeding on a composite flower like a daisy, where it will gracefully land on the petals of the disc flowers. The butterfly will elegantly unfurl its proboscis, insert it precisely through a long narrow tube of the central disc flowers, and drink nectar hidden inside. During this process, a cleverly positioned anther rubs against the butterfly, transferring pollen to its body. After drinking nectar, the butterfly flutters away carrying pollen to the next bloom where the pollen will brush against the stigma.
Now consider beetles, which are sometimes referred to as “mess and soil” pollinators. These more primitive insects blunder their way through a bloom searching for food, a mate, all while defecating inside the flower. Beetles come to the flowers in search of a snack. Magnolias’ strongly fruited or slightly fetid smells have to do with their pollinators’ preference for strong, fermenting smells.
The ample pollen of magnolia blossoms is what makes beetles messy. Picture beetles, which don’t possess special pollen collecting features, getting covered in pollen as they flounder about in the bowl formed by the large the petals of a magnolia, and then carrying that pollen on to the next flower. The beetle’s process may not be refined like that of the butterfly, but it is just as necessary for certain plants. Beetles and magnolias existed before bees and butterflies and their unique connection was developed well before other players arrived to the pollination game.
In the end, pollination is all about survival and sex. The insect and the plant both want something. Often, the pollinator is drawn to a plant with an offer of food. In turn, the plant uses the pollinator as a vector to move its pollen to the stigma of another flower. Plants have evolved with particular traits, and pollinators select blooms for their preference for color, odor, nectar, nectar guides, pollen, and flower shape. These traits, combined with bloom period and location make for a variable matrix of pollinator and plant interactions. Therefore, it is important to grow a large selection of plants for various pollinators to support their needs. Look at the Pollinator Syndrome Traits Table. Each type of pollinator deserves to have their story told, so that we can better understand their important roles.
A Pollinator Garden Evolves
In 1995, Smithsonian Gardens opened the Butterfly Habitat Garden: an 11,000-square-foot garden along the east side of the National Museum of Natural History in the heart of Washington, DC. After 20 years, this popular landscape was renamed the Pollinator Garden, during a Pollinator Week celebration in June of 2016. The garden’s new theme focuses on the Pollination Investigation that takes visitors on a discovery of the “who, what, when, where, why, and how” of pollination by interpreting the unique relationship between pollinators and flowers.
The garden’s title change and Smithsonian Gardens’ extended educational efforts reflect the growing importance of supporting pollinator health championed by the formation of a task force by President Barack Obama in 2014. Smithsonian Gardens’ reinterpretation and branding of the Pollinator Garden on the National Mall will educate millions of visitors on the wide diversity of pollinators and the types of plants that support them.
This garden now has people thinking beyond butterflies and honeybees by including seven “pollinator profiles” for bees, beetles, butterflies, hummingbirds, flies, moths and the wind, with special mentions of bats and water pollination. Using a field journal theme each profile describes the pollinators “favorite flowers” using the pollinator syndromes; color, nectar guides, odor, nectar, pollen, and flower shape. The garden display also shows what can be done to create beautiful pollinator-friendly gardens. The panels teach pollination on a general level and not specifically scripted to the Smithsonian Pollinator Garden.
On May 20, 2018, the same panels were unveiled at University of Ljubljana Botanical Garden as part of the first World Bee Day. The United Nations declared the first World Bee Day after a proposal by the Republic of Slovenia. Additionally, the Pollination Investigation panels will be released to educators in gardens around the world free of charge through Smithsonian Gardens (www.gardens.si.edu).
Smithsonian Gardens: As a vital and vibrant part of the Smithsonian experience, we engage, people with plants and gardens, inform on the roles both play in our cultural and natural worlds, and inspire appreciation and stewardship. James Gagliardi is a supervisory horticulturist with Smithsonian Gardens in Washington, D.C. Holly Walker is the Plant Health Specialist at the Smithsonian Gardens in Washington, D.C.
The Monarch Joint Venture is a national partnership of federal and state agencies, non-governmental organizations, businesses and academic programs working together to conserve the monarch butterfly migration. The content in this article does not necessarily reflect the positions of all Monarch Joint Venture partners. Header photo by James Gagliardi.