Love is not love which alters when it alteration finds

In 340 B.C., Aristotle noticed that honey bees tend to choose just one flower species during a foraging flight. This behavior, termed flower constancy, continues to puzzle scientists today. Why, when they could select other nearby flowers that are more “rewarding”—offer more nectar—do honey bees, bumble bees, and some butterflies visit only one kind of flower per trip?

Honey bee on camas flower-photo Victor Berthelsdorf

    Flower constancy works out well for flowering plants. Pollen sticks to the bodies of bees and other pollinators as they collect nectar. If the plant is lucky, some of that pollen will be deposited on a flower from the same species. A bee that visits only one flower species per trip is more likely to deposit the right pollen on the next flower, enabling it produce seeds. A fickle insect flitting between different kinds of flowers may just clog the (female) stigma with irrelevant (male) pollen from other species. That explains how flower constancy helps plants. It doesn’t explain what’s in it for the insects.

Does visiting just one flower type help the bee?

    Scientists have come at this from several directions. One theory is that bees don’t have enough short-term memory to retain a schema of more than one flower to visit at a time. Another is that it’s too risky to invest time and cognitive energy into learning to find the nectar in another kind of flower; better to stick with a flower type that the bee knows will provide a good nectar supply. A third hypothesis is that social honey bees avoid conflict with sister bees from their hive by sticking to one kind of flower and leaving the rest for others to visit. 

Honey bees in the hive with their queen-photo Levi Asay

There are problems with each of these theories and a lack of data to support any of them. Bees aren’t as rigid as some of these discussions imply. They’ve been shown to adjust their flower choices when there’s a really juicy high-nectar alternative.

    On Valentine’s Day, I’d like to believe that flower constancy is actually intentional faithfulness. My husband Steve brings me pollen (actually, a whole bouquet of beautiful flowers) every year at this time. He hasn’t gotten sidetracked yet by any high-nectar cuties.

Received for Valentines Day. Bees, eat your hearts out!

    What do we really know about the inner life of bees? Do they have aesthetic tastes in flowers? Do they have other things to think about while they’re sipping nectar and bringing home pollen for their queen’s offspring? In the bee world, females do the work of transporting floral offerings. The males are lounging around the Drones Club between fulfilling their reproductive role.

Drone bee-photo Epgui

    A worker bee only lives for three to six weeks, during which all her labor goes toward the collective good. She’s not going to mate or have children. Maybe she feels alienated at the hive and happiest when she’s out in the sunlight landing on particular flower petals. She could add variety to her trip with a mixture of blooms, but she doesn’t.

Worker bee making her own choices

    Let’s give her some credit for making a strong positive choice. Why just one kind of flower? Because that’s what she wants.

A curtain of vines

Thinking about ways to reduce our energy use for cooling next summer, I hit on the idea of shading some west-facing windows at the back of the house with foliage. I don’t want to block the three full-length windows that provide our main view of the garden. But a pair of windows near the southwest corner could use some summer shade. Vines could be just the thing.

These windows get a lot of afternoon sun in summer

    The Department of Energy explains that vines can lower the temperature of a house in three ways. In the process of evapotranspiration, plants actively transport water, and when it evaporates, it cools the surrounding air. Shade reduces solar gain, of course, and vines can blanket the side of the house, creating an insulating air space. Put together, these contributions can reduce temperature shifts by 50 percent.

Vines can keep a house cool-photo Michael Palmer

    I’m not proposing to cover the whole west side of the house in vines yet. My idea is to start with a large container of fast-growing vines to keep the sun off that pair of windows.

    When I put up supports, I’d like to leave space between the vines and the house to permit air flow. I’m picturing a wooden frame attached to the siding that would hold some lattice or wire fencing to support the vines. Maybe I can attach hinges at the bottom of the frame so I can swing it down when it comes time to paint the house again.

Lattice attached closely to the garage wall leaves little air space behind it

    I’ve learned a lesson from a large wooden planter I placed directly on the ground in a shady corner. Tree roots grew up into the potting mix, making it hard to remove and replace old growing medium in the spring. This time I’ll prevent that by standing the planter’s corners on bricks to leave an air space that the roots can’t jump.

    Next will come the fun part: choosing which vines to grow. I could go with classic fast-growing flowering climbers such morning glory (Ipomoea purpurea), moonflower (Ipomoea alba), or mandevilla (Mandevilla spp.). These all originate in Central America. I could choose edible options: scarlet runner beans, cucumbers or squash. 

Morning glories are lovely and grow fast

    But I'd prefer to use native vines. I’ve already got two trumpet honeysuckles (Lonicera sempervirens), a cross-vine (Bignonia capreolata), and a trumpet vine (Campsis radicans) close enough to the proposed site that I’d like to try something different.

Trumpet honeysuckle is going strong in a dry spot against the house

    Last summer I grew a blue passionflower (Passiflora caerulea) vine in a container on the deck, wrapping its long stems around a black metal obelisk stuck in the pot. That one’s from South America. There’s a native cousin called maypop (Passiflora incarnata) that looks pretty. It’s reportedly a woody vine in the Southeast that dies to the ground in colder areas, which would serve my purpose. Growing it in a planter would curb its tendency to aggressive root spread.

Maypop, a native passionflower-photo H. Zell

    Another native possibility is woodbine (Clematis virginiana), a vigorous grower with white flowers August to October that could accept cutting back in winter. A quick search uncovers warnings about its spreading by seed, though, so maybe not.
   

Snowdrop clones

Snowdrops (Galanthus nivalis) are blooming in my front yard, a hopeful harbinger of spring. From the flower’s point of view, what’s the point of blooming so early? I read that bumblebee queens, who survive for several years, may emerge early enough to pollinate these very early flowers, allowing them to set seed, as they would in their home range in Europe and Asia. 

Snowdrops have slowly formed clumps in the front yard

    But the expanding clumps of snowdrops in my garden are most likely clone colonies, groups of connected individuals whose genetic material is identical. Since they’re rarely able to produce seeds, they spread vegetatively as their bulbs reproduce underground and send up new plants.

Snowdrop bulbs can divide and make offsets-www.BioLib.de

    Snowdrops aren’t the only plants that increase this way, of course. The biggest clone colony in the world is a grove of quaking aspens (Populus tremuloides) in Utah called Pando, reputed to be the world’s largest living thing and one of the oldest. 

Pando in fall-the whole grove is one giant organism

Pando covers 106 acres, with about 40,000 genetically identical trunks growing from the shared root system, which is about 80,000 years old. When wildfires kill the trees above ground, the roots survive. Another venerable giant clone colony is the King Clone creosote bush (Larrea tridentata) in the Mojave Desert. 

     In my own yard I’ve got more modest colony formers such as pawpaw (Asimina triloba), sweetshrub (Calycanthus floridus), and highbush blueberry (Vaccinium corymbosum). 

Pawpaw sends out roots to form a clonal clump

    As we recall from high school biology, when two individuals get together to reproduce, their genes are mixed together in the process of meiosis. That gives each of their offspring a unique combination of genes, half from each parent. Colony formers spread asexually by mitosis--plain cell division--passing on the same genes to new individuals, which are clones of their parents. That doesn’t mean their genes never change, because mutations occur spontaneously over time. But the colony has mostly the same genes repeated over and over.

These snowdrops are genetically identical

    As much as I love seeing the clumps of snowdrops emerge from the leaf litter or the snow, I’d rather that most of my garden plants be more sexually active. When individual plants within a species differ genetically, a diversity of traits will give the species a better chance of coping with predators, disease, and climate change.

Potatoes blighted in the Irish Famine were clones without diverse defenses-USDA

    This is another reason to buy straight native plants rather than cultivars for my planned pollinator bed. Once a nursery spots a desirable flowering plant as the basis for a cultivar, they reproduce it asexually by cuttings, divisions, or tissue culture. They want new plants that are genetically identical to the desirable ancestor. Straight native species grown from seed, on the other hand, come from open (uncontrolled) pollination by insects, birds or wind. They’ll add biodiversity to the garden.

Open pollination supports genetic diversity

    Currently cultivars dominate the market. Sometimes even native plant nurseries have to offer plant selections or varieties that are truest to their species, because no straight natives are available. Let’s hope that will change as demand for native species increases.

I could only find a cultivar of this scarlet beebalm for sale, so I chose another species in the genus

Hopes for spring

The post-holiday doldrums have set in, and I’m looking for garden planning projects to remind me that spring is on the way. Inspired by Kim Eierman’s book, The Pollinator Victory Garden, I’m developing a short list of generously flowering perennials to provide my best pollen and nectar buffet ever.

Robin Wilkerson's Lincoln, MA garden in August 2017 - a pollinator feast

   May and June bring the most flowers in my garden, with another surge in October. My goal is to boost “floral resources” from July through September, when there’s less forage available for pollinators here. To produce the most flowers for visiting bees, flies, beetles, moths, and butterflies, the new plants will need as much sun as they can get in our yard. That’s why I’ll plant them around the garden pond, one of the sunniest areas. To date, the pond been surrounded on three sides by dwarf conifers, a Japanese maple, and a few perennials. 

Looking sad now, but you can see there's some space for flowers

    When the molded plastic pond liner was installed in 1997, its rim was covered with long pieces of bluestone, and smaller bluestone rectangles were dotted around it in a pleasing irregular pattern. I’m proposing to lift the smaller stones where I can to make space for summer bloomers. 

    Most of my summer flowers are yellow or orange. Around the pond, I’m going with purples and pinks. Working from lists from Kim’s website, ecobeneficial.com, and the Native Plant Trust, I’ve chosen some possibilities. They’re all native to Massachusetts, and this time I’m going to insist on straight species, not cultivars. 

    A cultivar is a plant that’s been selected from among the natives and reproduced asexually—through cuttings, divisions or tissue culture—to preserve some desirable characteristic. The problem is that new traits humans like may confuse insects, as when flower color or bloom time changes. In general, I’ve accepted cultivars that look similar to the straight native species as sustainable enough, but not this time. This bed will be completely pure.

This yellow tickseed, Coreopsis 'Zagreb,' is a cultivar that looks like the straight native species

    Here are some of my choices: I’ve been wanting to grow Joe Pye weed (Eutrochium maculatum) or its coastal cousin (Eutrochium dubium). 

Joe Pye weed

I’ll give anise hyssop (Agastache foeniculum) another chance. 

Anise hyssop-photo R. A. Nonenmacher

I’ve stayed away from beebalm because I feared it would take over the garden. Now I’ll try some, possibly spotted beebalm, AKA horsemint (Monarda punctata), which has intriguing flowers combining pinkish-purple, green, beige, and maroon. 

Distinctive horsemint flowers

I’ve got to try mountain mint (Pycnanthemum muticum), which also has muted flower colors. It’s reputed to be a superstar for attracting pollinators.

Mountain mint is a pollinator magnet

And asters will fill in the gaps, not just late-blooming New England aster (Symphyotrichum novae-angliae) but possibly also New York aster (S. novi-belgii) or smooth aster (S. laeve), both of which flower during my preferred summer window.

Smooth aster starts blooming in early September-photo Heike Löchel

    I’m hoping to combine different flower forms, from the daisy-shaped aster flowers to beebalm’s tubes and Joe Pye weed’s compound balls. That’s to cater to the preferences of the different insects I hope to attract.

Butterflies with long tongues can sip from tubular flowers

    I may even be able to avoid plastic pots and buy some of these as bare root plants. Updates will follow.

Uncomfortably warm

We had record high temperatures last weekend, up to 74 degrees at Logan Airport on Sunday, the warmest January temperature ever recorded in Boston. For us humans, it was a pleasant break from winter cold. Scientists in town for the American Meteorological Society’s annual meeting linked the freakish weather to the trend toward global warming.

    After my friend Amy noticed that some blue vinca flowers (Vinca minor) had opened, I checked and found some in my front yard too. 

Vinca flower looking peaked after Friday's cold

My Asian witch hazel (Hamamelis mollis) is in full bloom in the backyard. The danger is that these early bloomers started up their spring metabolism too soon, and they’ll suffer for it. By Friday, we were back to a windchill of 5°F.

So far the witch hazel flowers are holding up

    I’m hoping that despite the White House’s attempts to deny what everyone else knows, we’re finally squaring up to serious action to address global warming. Meanwhile, though, we’re warned that even if we immediately reduced carbon pollution radically, we’d still have to expect climate effects that have already been set in motion.

    In the garden, I’m afraid this doesn’t mean I’ll be picking mangoes and pineapples. 

We could end up with waterfront property due to sea level rise, but the palm trees are unlikely

Instead, I’m expecting more winter warm spells alternating with vicious cold without snow cover. That’s already been happening in recent winters, and it’s especially hard on my shrubs and vines.

    I particularly notice the effects of uneven winter temperatures on a climbing rose that grows near the house on the garage and an adjacent pergola over the garden gate. 

    When I started the garden thirty years ago, I planted Rose ‘New Dawn,’ in this spot. I learned later that some garden designers regarded ‘New Dawn’ as a boring cliché, but to me it was the epitome of rose charm. I pictured a romantic cloud of blush pink roses spilling over the gateway. 

'New Dawn' is my idea of a romantic climber

After a few years, that did happen—sometimes. A winter warm spell followed by a cold snap could kill back even this tough survivor.

Rose canes exposed to chilling winds. Cross-vine leaves are still clinging on in January.

    At first the vine bounced back, quickly sending up new canes to replace killed ones. In the last couple of years, it seems to be struggling just to survive, and flowering has been sparse. ‘New Dawn’ is rated as hardy to Zone 5, meaning that it can bear the cold down to -20 F, lower than what we get in this area. I think it’s the cold, drying wind when there’s no insulating snow that’s depleting the vine’s reserves as the assault is repeated year after year. It’s got only so much stored energy for repairs.

    To help ‘New Dawn’ and my other favorites survive the new climate reality, I’m resolving to surround their bases with some compost and composted cow manure next spring to help them store up energy during the warm season. To me, shrubs wrapped in burlap through the winter are an eyesore. 

Poor thing!

But I might break down next fall and pile up some leaves or soil around shrub and vine crowns for a little extra insulation. As I post this, there's snow on the ground again, thank goodness!

Another reason to keep garden waste at home

A new book that came in the mail, The Pollinator Victory Garden by Kim Eierman, made me glad that I'd started a brush pile this fall. Until recently, I couldn’t picture a suitable spot for this amenity in my third-of-an-acre suburban lot.

    The ecological reason to cultivate a brush pile is to provide wildlife habitat. Kim Eierman’s book focuses on insects, so she recommends brush piles as shelter for bees. She points out that 30 percent of North America’s 4,000 native bees are cavity nesters. They need safe small spaces where they’re sheltered from the rain. Some find cavities that birds or other insects have made in dead trees, stumps or fallen logs.

Carpenter bees are cavity nesters-photo Anita Gould

    Other than wood chip mulch, there’s a shortage of dead wood on the ground in our yard, due to my previous habit of cleaning up at soil level. I now realize that’s unnecessary and eliminates potential habitat for creatures I want in the garden. I’m allowing dead tree limbs to lie on the ground in inconspicuous spots, but it’ll be a while before they soften and rot.

This downed tree in a local conservation area offers shelter for native insects

    The brush pile I’ve started intends to serve a dual purpose: containing our over-enthusiastic puppy and offering shelter for wildlife. Eager to play together, our Lola and Ruby, the dog next door, discovered spots where they could dig under the wooden fence between their yards. 

"Who, me?"

They applied themselves with energy. I went to work reinforcing our perimeter with wire fencing held down with bricks, paving stones, and any big rocks I could find. 

    There was a vulnerable space between two wire compost bins and the new chain link fence that joins the wooden fence line. I blocked off this corner with more wire fencing. In addition to foiling a homegrown prison break, the narrow, enclosed space now houses my new brush pile. As I build up the pile, I plan to add bundles of twigs tied with twine to keep insect nests dry.

Starting the brush pile with pine branches that came down in a heavy wind

    Cavity-nesting bees also find spaces inside plant stems. I’m already accommodating them by letting stalks stand through the winter. We’ve got elderberry, raspberry, and hydrangea bushes, so I’m glad to hear that their pithy stems make particularly good nesting spots.

Spongy stems of oak leaf hydrangea can be excavated by bees to make nests

    I love the idea of an insect hotel. That’s a human-made collection of promising nesting material, such as bunches of hollow stalks tightly packed together, clumps of dry leaves, cut lengths of bamboo stakes, ceramic blocks with small cavities built in, and tree branches or chunks of lumber with holes drilled for convenient insect access. 

This is an insect hotel in Germany. Cool, right?

The thing about this approach, though, is that the cavities need periodic cleaning. I’m not sure I can be counted on to clean an insect hotel on a regular schedule. For now, I’m letting nature do the work.

    After reading the first chapter of Kim’s book, I can already tell it’s going to up my game. While I wait to put Kim’s advice into practice next spring, I’ll be throwing fallen branches on the brush pile instead of filling yard waste bags.

 

Pest control without pesticides

It’s nice to hear about solutions for insect problems other than spraying pesticides. I’ve been a fan of biocontrol—introduction of nonnative insect predators to reduce populations of problematic insects—since I was able to stop spraying my trees for winter moth (Operophtera brumata). 

Winter moth-photo Ben Sale

This lucky turn of events came about because UMass entomologist Joseph Elkinton built up populations of Cyzenis albicans, a tiny parasitic fly that kills moth larvae. As substantial fly populations were established, winter moth damage became a non-issue. The parasitic fly attacks only winter moth and doesn’t prey on native insects.

    Since the winter moth success, I’ve learned about another clever use of a specialist insect, Hypena opulenta, a moth native to Ukraine. This moth eats the leaves of black swallow-wort (Vincetoxicum nigrum) a pernicious vine from the same region that’s causing problems in New England and elsewhere. 

Black swallow-wort, a nonnative invasive vine

Among other negatives, swallow-wort tricks monarch butterflies into laying eggs on its leaves, where larvae starve because they can’t eat swallow-wort foliage. Struggling monarchs don’t need this added trouble.

A monarch nectaring on the real thing, native showy milkweeed

    Boston’s Arnold Arboretum started releasing the Ukrainian moths this spring and saw them defoliate swallow-wort significantly in a test plot. Biocontrol is particularly welcome in the case of swallow-wort, because it’s really hard to pull out. Stems break off at ground level and send up new stalks. Some towns have asked Boy and Girl Scouts to pick unripe pods of swallow-wort vines and dispose of them before they can spread their seeds to the wind. This still sounds like a good idea, because the moths aren’t expected to wipe out swallow-wort, just reduce and control its population and spread.

    Meanwhile, scientists at the University of Rhode Island are working to establish the best predators for red lily beetles (Lilioceris lilii) that chew lilies, especially the Asiatic species, into unsightly stumps covered with beetle excrement. They've released three kinds of parasitoid wasps and are achieving some success.

Red lily beetles at work on a lily stem-photo Charles J Sharp

    When I started gardening back in the 1970s, organic gardening guides promoted the idea of companion planting, claiming that interplanting with herbs or annuals would keep chewing insects from damaging vegetable crops. 


    Unfortunately, this conventional wisdom often turns out to be wishful thinking. Thomas Christopher, in a recent blog post, traces the advice back to Ehrenfreid Pfeiffer, an early 20th century soil scientist and advocate of biodynamic gardening. Pfeiffer conducted bogus experiments purporting to show that certain plants were compatible. The idea was picked up and spread by J.I. Rodale, publisher of Organic Gardening. The nasturtiums, alyssum and marigolds I still dot around my vegetable bed originate from this myth. Most gardeners never traced it back to its faulty source.

Marigolds are nice, but they're probably not protecting my vegetable plants

    Christopher directs readers to a reliable review of companion planting by garden designer Robert Kourik. The scientific papers he cites show a more nuanced picture. Many of the usually recommended flowering plants don’t help to defend food plants, but some do attract beneficial insects that can reduce populations of leaf-eaters. Another reminder of the importance of healthy skepticism about gardening advice.