Dr. Andony Melathopolous hosted us on his fabulous PolliNation podcast.
Listen to the episode, where we talk about the importance of gardens to native bees, our current research, and some key questions that remain to be answered regarding gardening for bees.
This entry is from Lucas Costner, an undergraduate horticulture major at Oregon State University. It highlights one of the plants that Aaron Anderson is using in his research.
A native been rolls around inside of a California poppy at the North Willamette Research and Extension Center.
Having moved to Oregon from Michigan this past spring, one of my first memories of the state was the explosion of bright orange and yellow flowers lining the interstate and covering the hills. These ubiquitous flowers were, of course, California poppies (Escscholzia californica). Native to a range covering southern Washington south to the Sonoran Desert, the plant has spread throughout most of North America and onto other continents thanks to human intervention (1). This should come to no surprise to those familiar with the plant, because it is easy to grow and thrives in average soil, as long as drainage is good and there is plenty of sun (3).
California poppies can be grown as perennials or annuals, depending on the severity of the winters (3). The grey-green, finely divided foliage erupts with brightly colored flowers in the spring, but can continue flowering across the growing season if conditions are favorable (1). Long, spindly seed pods appear quickly following pollination and, once dry, easily explode, spreading baby poppies up to six feet away from the parent plant (1). If you’re looking to add these beauties to your own garden, it is best to spread seeds on the surface of the soil in the fall to ensure that dormancy is broken (1). But gardener beware: once established, California poppies are around for the long haul (3).
These flowers have been grown or collected for hundreds of years by the societies that have encountered them (1). Indigenous North Americans first used the plants for a variety of medicinal purposes and the plant quickly rose to fame in Victorian gardens after it was collected by David Douglas for the Royal Botanical Society of England in 1836 (1, 3). Western medicine has also found use of the California poppy, isolating over 30 chemicals for uses ranging from anti-bacterial agents to the treatment of cancer (1). For horticultural purposes, the Royal Horticultural Society today recommends planting along borders, for cut flowers, to create a sense of informality as in a cottage garden, as well as for gravel and rock gardens (4).
The act of gardening is unique in that it strikes a balance between control of and surrender to the natural world. On the one hand, the plants we decide to grow on our little slices of paradise are an irrevocable extension of us and our own stories; however, these plants have their own stories to tell and they transform us into participants of these stories whether we are willing or not. I’ve never heard anyone say, for example, that they planted such-and-such prize-winning hosta to attract deer to their garden. Yet, when these majestic 150-pound creatures sneak silently into our yards for a midnight snack, it’s hard to argue they weren’t invited. The plants we choose act as our ambassadors to a biotic world just beyond our grasp, providing food and habitat for a full spectrum of wildlife. On a larger scale, the landscapes we cultivate can collectively affect everything from water resources to the climate.
While it’s true that I’ve never heard anyone say they are planting for the deer, us gardeners have certainly taken a liking to another sort of creature. The insects of the Anthophila clade, otherwise known as the bees, have found a special place in our hearts. Maybe writer Michael Pollan was on to something when he recognized, in The Botany of Desire, the mirrored way in which the bees visiting his garden had found themselves in the servitude of the plants just as he was. While the gardener tends to the plants’ every need, the bee unwittingly ensures their reproductive success by transporting pollen from flower to flower. Or maybe its the recognition that we ultimately depend on pollinators for our own food security and survival. Whatever the underlying cause behind our species’ admiration of bees, cultivating a diversity of flowers is the surest way to invite them to and help them persist in our landscapes.
A syrphid fly pays a visit to a California poppy at the North Willamette Research and Extension Center.
Whether you sow the seeds of the California poppy simply for its beauty, for its natural history, to help prevent erosion, or for any other reason, you will also inevitably be providing a source of food for our favorite insects, the bees. Surprisingly California poppies don’t provide nectar for pollinators, just pollen, but they are still heavily visited by our native bumblebees, sweat bees, and mining bees, as well as the European honey bee (Apis mellifera) (1, 2). They are also visited by beautiful butterflies, beneficial minute pirate bugs, and glistening beetles (1). Additionally, from our observations at the North Willamette Research and Extension Center, I can personally attest to the California poppy’s popularity amongst a variety of syrphid flies.
As a student interested in creating functional habitat for both humans and wildlife, it truly matters little to me on its face if a plant is native or not. Gardens consisting of native plants can be just as gorgeous and moving as gardens consisting of exotic species — this is true. What does matter to me are the relationships these plants have with other organisms, and what that looks like in a world increasingly and unavoidably modified by humans. So, whether or not you decide to bring the California poppy or any other native plants into your own garden, I hope you do feel inspired to think about these plants in terms of their role in the wider community of life with which we share this planet.
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A female virescent green metallic bee. Image from United States Geological Survey Bee Inventory and Monitoring Lab.
This entry is from Lucas Costner, an undergraduate horticulture student at Oregon State University. It highlights a common Oregon pollinator.
While there are approximately 4,000 species of native bees in the United States (an estimated 500 of which call Oregon home), I’ve decidedly landed on one as my very favorite (1, 2). This flying iridescent blue-green gem, covered in golden hairs, and sporting a pitch black abdomen with white or yellow bands is Agapostemon virescens, the virescent green metallic bee. Found throughout the United States and southern Canada, these members of the sweat bee family (Halictidae) are common and beautiful (3).
As with other species of the genus Agapostemon, the virescent green metallic bee is a communal soil nester (3). These nests are composed of underground tunnel systems, marked by a main vertical burrow that branches off into several larger nesting areas complete with horizontally running tunnels and cells (4). In these cells, female bees leave a gift of pollen and nectar for a single egg before filling the tunnel with an insulating layer of soil (4). Soon a babe is hatched and, after eating and growing, the mature offspring dig their way out to start foraging!
Virescent green metallic bees are polylectic, meaning they collect pollen from a wide variety of floral resources (4). This is lucky for us gardeners, because we can plant from over a dozen common flower genera and provide the bees with forage. This point is underscored by a 2014 study that sampled bee species in Chicago, finding that the virescent green metallic bee was one of the most common species in the city (5). The same study noted that in more densely populated neighborhoods, the overall composition of bees shifted to more heavily consist of bees like the virescent green metallic bee and the European honey bee (5). As our cities continue to grow and the needs of urban communities become more pressing, this is good news for the virescent green metallic bee and other generalist pollinator species that can benefit from a relatively wide selection of floral resources.
A virescent green metallic bee emerging from a nest. Image from the University of Maine Cooperative Extension.
Having met the virescent green metallic bee for the first time this past summer working with Aaron Anderson on his native plants study at the North Willamette Research and Extension Center, I was curious to see which plants selected for the study had been previously identified as providing forage for the bee. From our list, the common sunflower (Helianthus annuus), yarrow (Achillea millefolium), showy milkweed (Asclepias speciosa), Douglas aster, (Symphyotrichum subspicatus), common camas (Camassia leichtlinii), wild strawberry (Fragraria vesca), Oregon iris (Iris tenax), sedum (Sedum oregonense), and goldenrod (Solidago canadensis) all make the cut (3).
Flowers are important for these bees for more than just food, however; as they also provide a rather scenic backdrop for the crucial business of mating. While female bees will return to the nest after emerging from the incubator cells in the spring, the male bees spend their days foraging, mating, and sleeping out in the cold, eventually dying at the end of the season (4). The females are the real beneficiaries of the underground nests, returning here to hibernate and lay their own eggs, and sharing in the joint responsibilities of guarding and maintaining the tunnels (4).
My favorite green bee may be relatively abundant and may not require as much help as other species in the way of specific planting regimes, but (as with all native ground nesting bees) leaving some undisturbed open space in your yard or garden can go along way to provide habitat. According to the Xerxes Society, nearly 70% of all native bees are ground nesters (6). To offer nesting habitat in your garden, simply leaving a couple feet of well-drained, bare or sparsely vegetated soil available in a sunny location will do (1, 6). The bees will take care of the rest — hopefully you will have the opportunity to enjoy them in your own garden next summer!
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This entry is from Lucas Costner, an undergraduate horticulture student at Oregon State University. It highlights a common Oregon pollinator.
A common feature of the urban and suburban landscape, a street lined with large London plane trees (Platanus x acerifolia), complete with lumpy trunks and exfoliating bark, can be a delight to behold. The tree was the favorite species of New York City planner Robert Moses, and became one popular choice for replacing elms affected by the infamous Dutch elm disease during the previous century (1). Chosen for its long life span, interesting growth habit, and ability to withstand the challenges of street life, the London plane has become a ubiquitous member of our cultivated environment. By happy accident, the tree also plays host to the larvae of the familiar and striking western tiger swallowtail (Papilio rutulus) (3).
This large yellow and black butterfly is found throughout the western continental United States and into southern British Columbia. Swallowtails tend to be specialists (2), so the addition of known host trees like the London plane and other members of the Platanus genus, along with willows (Salix spp.), poplars (Populus spp.), and alders (Alnus spp.) is of benefit not only to our parks, streets, and yards, but to these incredible pollinators as well (3). Adult females lay single eggs on the undersides of the leaves of host trees, which then provide food for the developing larvae (4). These larvae eventually form chrysalids and overwinter, emerging the following season as, well, beautiful butterflies (4). While the larvae of the western tiger swallowtail have somewhat specific tastes, the adult butterflies will feast on nectar from many flowering species. These pollinators typically take flight from June through July, but in Pacific coastal areas may be found throughout much of the year (3). They are noted as preferring wetter areas generally, and even as being avid visitors to mud-puddles (5).
Butterflies are of course important to us as gardeners because of the pollination services they provide, but throughout their lifespan they also play an important role as food for other organisms. Douglas Tallamy, from the University of Delaware, writes “if we were forced to care for only one group of insects in our restored suburban ecosystem, we would do well to choose the Lepidoptera” (the order consisting of moths and butterflies) (2). Fortunately for the western tiger swallowtail, and for those of us who enjoy its beauty, our cultivated landscapes should provide ample habitat. With that being said, global declines in flying insects are being documented (see: Insects are In Serious Trouble), and our attention needs to remain fixed as much on what we are planting as on how we are managing these landscapes.
Personally, I wasn’t fortunate enough to see many species of Lepidoptera this past season. I did manage to catch sight of a western tiger swallowtail early in the year, however, at the North Willamette Research and Extension Center foraging on a patch of showy milkweed (pictured above) neighboring the native plants study plot. Being a recent transplant from east of the Rockies, this was my first time ever seeing the butterfly and I was truly blown away. I’m hopeful that despite the challenges faced by these and other pollinators, we will all be able to enjoy them well into the future.
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Image source: https://www.flickr.com/photos/12567713@N00/2809146063
This entry is from Lucas Costner, an undergraduate horticulture major at Oregon State University. It highlights one of the plants that Aaron Anderson is using in his research.
A common and much-beloved Northwest native, the Douglas aster, happens to be a bit of a misnomer. This profusely blooming, purple-flowered perennial isn’t a member of the Old World Aster genus, but rather belongs to the New World Symphyotrichum (2). As such, our Douglas aster (Symphyotrichum subspicatum) is closely related to its East Coast look-alike, the New England aster (Symphyotrichum novae-angliae), and evidence suggests the two descend from a common ancestor (2).
Naming conventions aside, the Douglas aster should be noted for offering an impressive, season-long (July – September) display of attractive, disk-shaped, and papery flowers while asking for little in return. Like many of the other native plants I have written about to this date, this plant is incredibly hardy and will spread via creeping rhizomes if given the opportunity (3). The USDA Natural Resources Conservation Service recognizes the Douglas aster as being abundant and present from Alaska to California, and into Idaho and Montana (1). In the wild, it is noted as being found in forests, along the banks of streams, and even along the coast (3).
In Oregon gardens, west of the Cascades, the Douglas aster will again require little in terms of care once established. It does prefer full-sun, and well-drained soil, but it similarly thrives in wetland areas (4). Our test subjects in the field faced many hardships, ranging from drought to over-zealous mowing, and still ended up thriving. Therefore, as with the majority of the native plants written about here, this plant may not be appropriate for every garden or indeed for every gardener. The most exciting part about the Douglas aster, however, is not its robust growth habit; but rather, its potential to benefit wildlife and therefore our suburban and urban environments.
In the field, other members of the Asteraceae family (think goldenrod and pearly everlasting) have anecdotally been some of the most popular plants in terms of pollinating visitors, and our Douglas aster plots were no exception. At times, it was hard to keep track of just which insects had or had not been counted during our five minute observations due to their sheer abundance. Thanks to the long bloom period, it was also exciting to the see the progression of pollinators develop as the season passed week by week, and the species composition gradually changed. While the Douglas aster is noted for its attractiveness to many species of butterflies, our observations could suggest that is similarly attractive to a fairly wide array of bees as well (4).
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Getting ready to install plants at our field site.
The post below comes from Aaron Anderson, a M.S. student in the OSU Department of Horticulture, and a member of the Garden Ecology Lab.
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This past summer, we conducted the first field season of a study screening native plants for their attractiveness to pollinators and natural enemies. We selected 23 native Willamette Valley wildflower species based on drought tolerance, as well as four exotic garden species known to be attractive to bees: Nepeta cataria ‘Catnip’; Salvia elegans ‘Pineapple Sage’; Origanum vulgare ‘Italian’; Lavandula intermedia ‘Grosso’.
Table 1. Native plants selected for this study.
| Plant Species | Common Name | Life History | Bloom Color |
| Clarkia amoena | Farewell-to-spring | Annual | Pink |
| Collinsia grandiflora | Giant blue eyed Mary | Annual | Blue |
| Gilia capitata | Globe gilia | Annual | Blue |
| Lupinus polycarpus | Miniature lupine | Annual | Purple/Blue |
| Madia elegans | Common madia | Annual | Yellow |
| Nemophila menziesii | Baby blue eyes | Annual | Blue/White |
| Eschscholzia californica | California Poppy | Annual | Orange |
| Helianthus annuus | Common sunflower | Annual | Yellow |
| Phacelia heterophylla | Varied-leaf phacelia | Annual | White |
| Acmispon (Lotus) parviflorus | Annual | White/Pink | |
| Achillea millefolium | Yarrow | Perennial | White |
| Anaphalis margaritacea | Pearly everlasting | Perennial | White |
| Asclepias speciosa | Showy milkweed | Perennial | Pink/White |
| Aquilegia formosa | Western red columbine | Perennial | Red |
| Aster subspicatus | Douglas’ aster | Perennial | Purple |
| Camassia leichtlinii | Common camas | Perennial | Purple/White |
| Eriophyllum lanatum | Oregon sunshine | Perennial | Yellow |
| Fragaria vesca | Wild strawberry | Perennial | White |
| Iris tenax | Oregon iris | Perennial | Purple |
| Sedum oregonense | Cream Stonecrop | Perennial | Yellow |
| Sidalcea virgata | Rose Checkermallow | Perennial | Pink |
| Sisyrinchium idahoense | Blue-eyed grass | Perennial | Blue/Purple |
| Solidago canadensis | Goldenrod | Perennial | Yellow |
We planted them in meter squared plots at OSU’s North Willamette Research Center. Between April and October, we monitored floral visitation, sampled visiting insects using an “insect vacuum”, and tracked floral bloom.
With one season in the books, we have some purely anecdotal impressions of which wildflower species are the most attractive to bees. Goldenrod (Solidago canadensis) and Douglas aster (Symphyotrichum subspicatum) were both highly attractive to a wide diversity of native bees, as well as to a variety of beetles, bugs, and syrphid flies. As an added bonus, both these species had long bloom durations, providing habitat and colorful displays for significant portions of the summer. Annual flowers Clarkia amoena and Gilia capitata attracted a range of native bees; Clarkia was also visited by leafcutter bees for a different purpose – cutting circular petal slices to build nest cells with.
Bumblebee on Clarkia.
Syrphid fly on Goldenrod.
Results from this year need to be analyzed, and further research is needed to account for seasonal variability and to gather more data on floral visitors.
Additionally, w e will ask the public to rate the attractiveness of each of our study flower species in an effort to determine the best candidates for garden use. After a few more field seasons (and sorting lots of frozen insect samples!), the result of this study will be a pollinator planting list for home gardeners, as well as a pollinator and natural enemy friendly plant list for agricultural areas. These will help inform deliberate plantings that increase the habitat value of planted areas.
A soil pit is used to understand the nature of subsoil strata.
The Benton County Master Gardener demonstration garden was one of our soil test sites. This site had vegetables growing in raised beds, and in in-ground beds.
The Benton County Master Gardener demonstration garden used intercropping techniques to suppress weed growth in their beds.
This post is modified from a submission from Michael Nelson. It details lessons learned from his survey of garden soils, across Corvallis, Oregon, and the Portland Metropolitan area. In September 2017, Michael sampled soils from about 25 gardens. These gardens used raised beds and/or in ground gardens to grow a variety of vegetables, herbs, and fruits. We wanted to study urban garden soils ~ and soils in raised beds versus in ground beds ~ for a few reasons. Specifically, we wanted to look at a few different questions:
I asked Michael to write up a short report on his summer work. What did he observe in the gardens? What did he hear from gardeners? Are there initial findings or impressions he could share? His report is below.
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We began this project to examine differences between raised and in-ground garden beds in urban areas. We conducted a short survey of each site, where we noted weed pressure, garden area (in meters squared), and crops grown. We also noted any concerns voiced by the gardeners, about their vegetable production site. We sampled garden beds and kept samples separate depending on the type of bed (in ground versus raised-bed). We are now processing the soil samples in the Central Analytical Laboratory of OSU, so that we can determine the chemical, physical, and biological characteristics of our garden soil samples.
A few initial observations:
The next steps in understanding garden soils are in research and application. In research, soil testing should be reconsidered with gardens in mind. There may be alternative processing techniques to reduce variability between test results and garden soil content. Theoretical models may be able to produce a metric which could be used to adjust the results of a standard soil test to reflect garden conditions more accurately.
In application, greater precision of terminology would allow for a more refined view and management of garden systems. In particular, bed-types should be grouped by their method of establishment (i.e. was soil transported to the garden, or not), rather than the presence or lack of a garden border. Additionally, organic mulches and compost should be considered in finer detail. The source of the product is important to determine what chemical content is being applied to the soil top. The physical structure of the product is important to relay the extent to which the mulch content will likely be incorporated into the soil, itself.
We’re still actively working to process and test samples. We look forward to sharing more results, in the near future.
A leaf-cutter bee found on farewell-to-spring at the North Willamette Research and Extension Center.
This entry is from Lucas Costner, an undergraduate horticulture major at Oregon State University. It highlights one of the plants that Aaron Anderson is using in his research.
Clarkia amoena or, as it is commonly known, farewell-to-spring, is a personal favorite of mine. An annual plant found throughout coastal areas ranging from British Columbia to California, the showy farewell-to-spring offers color, structure, and a lengthy bloom time for a variety of uses in the garden (1, 2). It is hardy from USDA zones 2 through 11, and prefers well-drained soil of average fertility (2). The type variety features upright stems with lanceolate leaves and cup-shaped pink and purple flowers, sometimes with reddish markings on the inside of the petals (1). There are cultivated varieties widely available for purchase as well, often with more profuse and different colored blooms (1). While farewell-to-spring is an annual plant, it will readily self-seed in areas meeting its rather undemanding growing conditions (1). You can, therefore, expect to see it year after year once established. Seeds can be sown directly on the surface of the soil in either fall or spring (2).
At the North Willamette Research and Extension Center, where we are conducting our native plants study, we have observed a number of insect pollinators visiting farewelll-to-spring, as well as a hummingbird, which managed to both startle and distract me while performing pollinator observations. Another honorable mention is due to the leaf-cutter bee, which Aaron and I witnessed time and again munching off pieces of Clarkia petal and carrying them to some unknown location. The USDA lists European honey bees, native bumbles and mason bees, as well as butterflies amongst the main insect pollinator visitors (2). These species, in addition to those anecdotally observed in the field, suggest that farewell-to-spring could be an excellent native addition to pollinator gardens, providing general forage to a wide variety of species.
Sources:
1. “Clarkia amonea.” Plant Finder, Missouri Botanical Garden, www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=283040&isprofile=0&.
2. Young-Mathews, A. 2012. Plant fact sheet for farewell to spring (Clarkia amoena). USDA-Natural Resources Conservation Service, Corvallis Plant Materials Center, Corvallis, OR.
This post was written by Isabella Messer, an undergraduate working in the Garden Ecology Lab.
The Gray Hairstreak (Strymon melinus(Hübner, 1818)) is a common butterfly in the US. Its habitat spans most of the country with the exception of some states in the midwest (1). The Gray Hairstreak is most common in the southeast but can also be found along the west coast, including Oregon and possibly some of your gardens (1). These butterflies can be identified by their ash-gray color of their wings, their noticeable white-bordered black median line, and a two orange patches on the outer angle of their hindwing (2). Due to their coloring, Gray Hairstreaks can be mistaken for an Eastern Tailed-Blue butterfly which also have orange spots on their hindwing s(3). However, the Eastern Tailed-Blue does not live in Oregon (4). If you want to attract more Gray Hairstreaks to your garden, it would be beneficial to plant goldenrod, mint, milkweed and winter cress (5). Keep an eye out on a sunny day for these sweet little beauties!
Gray Hairstreak in a Portland garden, August 2017
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One of the western pearly everlasting specimens from our Native Plant study.
Now that our lab group is working on native plants and native bees, I thought it would be fun to do a ‘Plant of the Week’ and ‘Bee of the Week’ series. This entry is from Lucas Costner, an undergraduate horticulture major at Oregon State University. It highlights one of the plants that Aaron Anderson is using in his research.
Out of all the plants we have looked at this field season, the western pearly everlasting (Anaphalis margaritacea) has been one of the most interesting. Initially not sure what to expect, the overall longevity, profuseness of bloom, and general hardiness in response to the growing conditions at our site and the wrath of some weeders/mowers have all been surprising. Suffice it to say the name pearly everlasting is well-deserved. These plants, bursting with small white and yellow disk-shaped flowers, can grow up to 3 feet in height and up to 2 feet in width (2).
The western pearly everlasting is a perennial (2) native to and found throughout most of the continental United States and Canada, excluding the southeastern states and notably North Dakota (1). It is the only naturally occurring species of the genus Anaphalis in North America (1), and is hardy through USDA zones 3 to 8 (2). In terms of care, pearly everlasting is very self-sufficient — just add sun! It grows well in areas with full sun to part shade, is drought tolerant, and requires little in the way of fertilizer or other soil amendments (2). Given the opportunity, western pearly everlasting has been known to spread aggressively in the soil via runners (2).
These plants are also interesting because they exhibit dioecy (3), meaning that the flowers are either male or female. This is rare amongst other members of the Asteraceae family, but it is a great evolutionary strategy to limit self-pollination. Purportedly, the plant plays host for caterpillars of the American Lady butterfly (Vanessa virginiensis) (4). Outside of this, however, the wildlife benefits are largely unknown.
After witnessing the vivacity of the western pearly everlasting myself, I think it would be of interest to anyone looking to fill a particularly dry and difficult area of the garden with a pleasant, native wildflower. While some of the other plants I have written about here (Solidago canadensis and Asclepias speciosa) are known to be spready, I cannot overemphasize how vigorously this plant has grown in the field. Every week I find myself being surprised by some new plantlet popping its head out the hard dry soil or a new set of inflorescences about to go into full bloom.
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