Pollinator Syndromes
Who Belongs to Whom
When I used to travel a lot for work, those European hotel breakfast buffets were sometimes the highlight of my day. I’d start off with the best of intentions: just a smattering of fresh fruit and perhaps a dollop of creamy yogurt with honey (sometimes straight from the comb!). Well, ok, with a sprinkle of house-made granola and nuts for crunch. Satisfaction would peak if they brought me coffee in its own little shiny pot.
Then I’d remember that the day’s agenda included no clear plans for lunch. Would there be any lunch? As a savvy business traveler I’d think, I should nibble just a touch more as a precaution; wouldn’t want to get hangry in the midst of sensitive discussions. Well, that little mind trick would open the levees: omelets-to-order, melt-in-your-mouth croissants with butter and tiny jars of jam, cheese – oh, the cheese platters! Sometimes there was even caviar. I mean, breakfast was included with our room rate. We’d paid for that spread. So it would’ve been irresponsible not to sample everything, right?
I’ve always imagined that a healthy native plant meadow is, to a bee, just like that breakfast buffet is to me: a cornucopia of gustatory delights, each more enticing than the last.
Turns out, though, our pollinator friends are a tad more discriminating than yours truly. Over millennia, in fact, pollinators and plants have developed a cross-kingdom buddy system in which animal/plant pairs have co-evolved physical characteristics allowing them to interact more successfully with their “partners” than with other species. This buddy system is known as “pollinator syndromes.”
In previous articles I’ve touched on how some insects are generalists and others are specialists. The generalists can feed, pollinate and reproduce on a wide variety of plants. Specialists, on the other hand, have very specific needs for food sources or reproductive habitat. Monarch butterflies are the classic example of a specialist, in that their caterpillars can feed only on milkweed plants.
Pollinator syndromes are another form of specialization. The gist is that plants want to avoid having some rakish bee grazing from Monarda to Rudbeckia to Pycnanthemum — the way I might approach my hotel breakfast — because it results in everyone getting the wrong kind of pollen. Instead, plants of a species expect a little brand loyalty from their pollinators. They want the same visitors to shuttle exclusively among them so they can reproduce with their own kind. To shorten the odds, some clever plants have evolved to limit their accessibility to a narrow set of pollinators.
See those stripes on the violet petals above? They’re not just decorative. They’re nectar guides, sort of like landing strips, making it easier for pollinators to find their target.
The image above shows a monkeyflower under human-visible light on the left and ultraviolet light on the right. The UV version sports prominent dark nectar guides in the throat of the flower. Plants with these types of guides will attract mostly bees and butterflies, who can see more of the UV spectrum than other pollinators.
Let’s not forget that flies are pollinators, too. Plants that want to attract flies have adopted a style heavy on dark red flowers and putrid scents to mimic – you guessed it – rotting meat. Skunk cabbage (Symplocarpus foetidus) fits this description.
Hidden nectar is another kind of pollinator syndrome. Long tubular flowers with the yummy stuff tucked away at the base will typically attract pollinators with long tongues, such as bees, butterflies and hummingbirds.
As you can see, the hummingbird clearwing moth above has a long tongue she can unfurl to fit nicely into the curved corolla of the Monarda (bee balm) flower.
The Lobelia cardinalis (cardinal flower) above deploys multiple strategies to attract, and ensure pollination from, hummingbirds. It has long tubular flowers in hummingbirds’ favorite color. It lacks a “perch”, which bees and butterflies require but hovering hummingbirds don’t need. Also, see that anther near the hummingbird’s forehead? While she’s nectaring, the anther will deposit pollen on her head, which she’ll then deliver to similarly-shaped and -located pollen-receiving stigma on another cardinal flower. Lobelia cardinalis is perfectly formed to coopt hummingbirds into its reproductive business.
By studying the traits of your flowers, you can predict what kind of pollinators they’ll attract. Or vice versa, if you’re hellbent on attracting flies, you now know what to do. Here’s a helpful chart from the U.S. Forest Service:
Plants and pollinators have figured out, in elaborate ways, who belongs with whom. Amazing! The last thing they need is for us blundering humans to disrupt their delicate calibrations with our scorched-earth landscapes of lawns and exotics. Let’s do our part by planting native plants – sticking as close as possible to straight species (plants the way nature designed them) – and letting the buddy system perform its magic.
Let me know in the comments if you’ve observed evidence of pollinator syndromes in your garden.
If you live in the DC vicinity and could use assistance with sustainable landscaping, visit Bees’ Knees Design. I’d be happy to help you.
Resources
Kristie Lane Anderson, “Lawns to Meadows,” lecture at Longwood Gardens, Jan 24, 2024.
“Pollinator Syndromes,” U.S. Forest Service, U.S. Department of Agriculture.
love the opening to this one.....and then I learned sumpin'
and love the Lumineers.
Keep 'em comin'
In my garden, a tough, gorgeous Gentiana andrewsii (closed bottle gentian) delights me and epitomizes specialist pollination.
Thank you, Lolly. Each newsletter is better than the last!