A contender

Since reading Bringing Nature Home in 2011, I’ve wanted to grow a black cherry tree (Prunus serotina). Doug Tallamy highlights this native tree in his book because it’s a champion at providing food for wildlife.

Black cherry in spring-photo Krzysztof Ziarnek, Kenrais

 The genus Prunus, which includes cherries, peaches, and almonds, is in the top three for supporting Lepidoptera (butterflies and moths). Black cherry also provides food for bees and other pollinators, and birds and many mammals eat its fruits.

A red-spotted purple on black cherry

    As it turned out, I didn’t have to go out and buy or even dig up a black cherry seedling. One arrived right on schedule in the clearing created when we removed two big hemlocks along the fence line. Black cherry travels when birds eat the berries (technically, drupes) and excrete the seeds wherever they go. An animal’s digestive system scarifies the seeds, breaking through their hard outer coating and preparing them to germinate.

The fruits turn from red to black

    Black cherry seems to have adapted particularly well to living around humans. It used to grow mostly in forests and can reach a height of 100 feet, which makes it the tallest cherry tree. But now it takes advantage of growth opportunities in areas of new construction or open ground such as the space left by our late hemlocks. Black cherry grows in sun or part shade and puts up with moist or dry conditions.

    Once you know what it looks like, you’ll spot this tree in many public places. 

Distinctive leaves

To me, the tip-off is the shiny leaves, extended ovals ending in a pointed tip. In spring it covers itself with wands of tiny white flowers.

The little white cherry flowers attract pollinators-photo AnRo0002

    I learned that black cherry has found a way to enlist ants to protect it from leaf-eating insects: extra-floral nectaries. As Ohio State University Extension blogger Joe Boggs writes, “Nectar is the currency used by plants to pay insects and other animals to do their bidding.” Most flowering plants locate this sugary liquid inside flowers, but many species add less conventional nectar outlets. Cherries ooze nectar from little knobs on the petioles, or leaf stems. 

The dark bumps on this leaf stalk are extra-floral nectaries

Ants swarm the foliage to harvest the nectar. While they’re at it, they eat leaf-eaters; for example, one visiting ant species preys on Eastern tent caterpillars.

    Although black cherry’s nectar and fruits are delectable, its leaves are poisonous. They contain glycosides that hydrolyze to hydrogen cyanide in an animal's digestive system. 

     With tolerance for a range of growing conditions, irresistible fruit and nectar, and dual strategies for defending its leaves, this tree is a resourceful survivor. When it was introduced to Europe, it became invasive there. Here it fits into plant communities without taking over.

    The black cherry that emerged last year in the new clearing is now three feet tall and bushy. The question for my garden will be how big I’ll let this tree get and how many of its relatives I’ll allow to grow here. With birds spreading the seeds, there will always be new saplings ready to fill any patch where sunlight reaches the ground.

A younger black cherry volunteering in the yard

High life for hummingbirds

Last year I gave up on my hummingbird feeder. I was concerned that I might be offering moldy or infected sugar water, because I couldn’t get around to refilling the feeder every day in hot weather. And truth to tell, I wasn’t seeing any hummingbirds using the feeder.

    Because they beat their wings constantly, hummingbirds have to keep eating whenever they’re awake, and at night they lower their metabolic rate to use less energy. They’re welcome in the garden community because their quest for nectar makes them important pollinators. They also eat lots of insects for protein, consuming up to half their body weight daily.

A hummingbird on the job, pollinating while it sips nectar

    This year I focused on growing flowers that would attract hummingbirds. Conventional advice is to offer a succession of red, orange and pink flowers with long tubular shapes from spring through fall. Recent research clarifies, though, that the birds seek out the location of known nectar sources rather than searching by flower color.

    Until this year, I’d rarely seen a hummingbird in the yard. This year I hoped to lure some to visit the back deck so I’d have a chance of seeing them. 

    Sure enough, we’ve seen hummingbirds near the house this summer. Yesterday one visited the cobalt-blue flowers of a hummingbird sage (Salvia guaranitica) growing in a big pot on the deck. 

That blur in the center of the photo is the hummingbird--best I could do

He hovered to dip his beak in the thin tubular flowers before darting away to perch on a nearby tree branch—the first time I’ve seen a hummingbird sitting still.

    I’ve also seen a hummingbird feeding from a tall meadow rue (Thalictrum rochebrunianum) that has sprays of tiny shallow lavender flowers, not trumpet-shaped at all. I guess the birds’ choice of flower shape must be a preference rather than an invariable rule.

Surprisingly, these flowers attracted a hummingbird

    So what accounts for more hummingbirds visiting the yard and coming near the house this year? I can’t be sure, but I have some guesses. First, I now have three honeysuckle vines (Lonicera sempervirens) blooming along the back and side of the house near the deck. 

Honeysuckle has everything hummingbirds like

Their flowering has lasted longer this summer than usual, perhaps because it’s been such a wet year. There’s that hummingbird sage, which started blooming in August and is covered with flowers. I’ve also learned that the old-fashioned magenta-flowered rhododendron (Rhododendron catawbiense) facing the deck is popular with the birds. Virginia bluebells (Mertensia virginica), whose trumpet-shaped flowers also offer nectar for hummingbirds, had a good year in a shady spot around the corner from the deck.

Virginia bluebells' blooms start pink and change to blue

    The yard also provides nesting material for hummingbirds: spider webs and dandelion fluff. I can’t take any credit for those; they’re just here. 

    Another important factor could have cleared the way for hummingbirds. Because they eat so many insects, they’re highly affected by pesticides. This is my first year with no pesticide spraying at all. I wasn’t thinking of hummingbirds when I made the decision to stop the last pesticide application, for winter moth. If it’s made a better life for hummingbirds, I’m glad.

Hummingbird sage draws other visitors too

Spare those weeds

Pulling out weeds always seems like a virtue, and letting them grow a sign of slovenliness. But it turns out that a few weedy patches promote biodiversity in the yard. 

A neighbor has let these weeds take over a stretch of curb strip

When we removed large hemlocks last year to avoid spraying them for hemlock woolly adelgid, we were left with two sunny clearings. I planted native shrubs and small trees, but it’ll be a few years before they grow big enough to fill the space. Meanwhile, lots of weeds have stepped forward to fill the open space.

A stand of what I think is hawkweed taking over some newly sunny ground

    With the idea that this could be a good, I’ve been looking up our weeds in Wild Urban Plants of the Northeast, Peter Del Tredici’s guide to “spontaneous urban vegetation.” Many are listed as “disturbance-adapted colonizer of bare ground,” true to their behavior in my yard.

    One of their useful functions is to provide food and habitat for beneficial insects, the ones that prey on leaf-eaters. Although these insects are predators in at least one life stage, they often need nectar and pollen in another. That’s one way that weeds such as lamb’s quarters and chickweed can be a plus.

Lamb's quarters wilting in this week's heat

Their flowers provide extra forage and fill in during the lean times when our preferred flowers aren’t blooming. Weeds may also attract prey insects that the beneficials need to eat or parasitize. 

    Here are some of the weeds that have popped up where the hemlocks grew:

Pokeweed (Phytolacca americana): This is a North American native that, although toxic to mammals, has fruits that birds love. At least 30 bird species use pokeberries as a major food source. 

Pokeweed grows quickly into a substantial presence

Warblers and other migratory birds eat them on their flights south. The berries help mockingbirds, cardinals, cedar waxwings, and others to get through the Northeastern winter. Pokeweed is larval food for several moth and butterfly species, including the giant leopard moth. Bees feed on its pollen.

Giant leopard moth-photo NPS Phillip Brown

Yellow woodsorrel (Oxalis stricta): Also a native, this low perennial shows up all over my garden. At summer camp we called it sour grass and chewed on the leaves when we were thirsty on a hike. 

Recognize this yellow woodsorrel? It's all over the place.

The plant’s tissues are high in oxalic acid, so it’s better to sample the leaves in moderation. It too provides seeds for birds, pollen for native insects, and leaves for butterfly and moth caterpillars.

Devil’s beggarticks (Bidens frondosa): This native annual gets the prize for its many colorful names: sticktight, devil's bootjack, pitchfork weed, Spanish needles. You can see it hasn’t made a lot of friends among gardeners, but it provides pollen for bees and, interestingly, food for muskrats when it grows near water.

Devil's beggarticks has pretty flowers; its bad rep comes from the burrs that follow.

    These weeds are easy for me to pull out, especially because they’re growing where I previously put down a layer of wood chip mulch. Under the wood chips, the soil stays soft. I’ll remove some weeds that are shading my squash and melon plants (a story for another day), but now I know to leave some for their contribution to the garden’s ecology.

Fooling some of the people all of the time

My email has brought me some interesting news relating to neonicotinoid insecticides. I received a message from the Friends of Newton Cemetery announcing that they’re creating a pollinator garden with a grant from Bayer. The cemetery is a beautiful park, generously open to the public. I wondered whether its horticultural staff knew that their garden to provide forage for pollinators was to be funded by one of the world’s top manufacturers and sellers of pollinator-killing neonics.

Newton Cemetery October 2017

    Bayer makes the best-selling neonic, imidacloprid, sold as Admire, Advantage, Confidor, Gaucho, Merit, Hachikusan, Kohinor, Premise, Prothor, and Winner. 

Merit

They also sell two other successful neonics, clothianidin and thiacloprid. Despite mounting scientific evidence, Bayer has consistently denied that neonics harm pollinators, including bees. They blame other factors, such as varroa mites, for the bee die-off. Their Bee Care Program and the entity that made the grant to Newton Cemetery, FeedABee, seem to be part of a campaign to combat negative publicity for Bayer’s insecticide products. Viewed in this light, the gift to the cemetery seems less community spirited.

How dumb do they think we are?

    But a pollinator garden is a good thing. I don’t see why the cemetery can’t accept Bayer’s money for an environmentally positive project. They just shouldn’t use it to buy plants treated with Bayer’s products, or other neonics. The insecticides persist for years in treated plants. Bees that contact them die or suffer neurological damage. 

Neonics can kill whole colonies or do more subtle harm

    I wrote back to the Friends of Newton Cemetery to ask whether they’ve found a source of reliably neonic-free annuals and perennials. In my experience, this has been a difficult quest, but a necessary one. Who wants a pollinator garden that kills pollinators?

I grew these marigolds from organic seed, so I know they won't kill bees

    Meanwhile, there’s some good news on the horizon about neonics. The Massachusetts legislature is considering a bill to ban the direct sale of the insecticides to consumers in our state. I was delighted to hear from my state senator, Cynthia Creem, that she cosponsored the bill, H4041, An Act to protect Massachusetts pollinators. Since the EPA hasn’t banned neonics, it’s up to the states to take action.

    Even if neonics aren’t sold directly to consumers, though, they’ll still affect insects in our gardens as long as garden centers and big box stores sell treated plants. Plant production is a global business. Wholesale nurseries source seeds all over the world. They buy tiny annual seedlings from rooting stations around the US and tissue culture products imported from as far afield as South Africa, Holland, Turkey, and Poland (tissue culture converts tiny pieces of plant tissue into large numbers of genetically identical plantlets). Giant plantations in Costa Rica and Ecuador send cuttings of perennials for US wholesalers to root and grow to saleable size.

The annuals we buy are international travelers

    As long as plants can be treated with neonics at any of these stops on their way to market, gardeners still risk exposing pollinators to the dangers of these chemicals. Home Depot has promised that its plants will be free of neonics by the end of 2018. It’s a start.

Summer singers

In August’s heat and humidity, my gardening activity is down to watering my container plants and occasionally deadheading. 

Growing vegetables on the deck

For someone choosing flowers to accommodate bugs, I don’t know enough about the insects, their lives and habits. This seems like a good time to learn about a few. I started with the singers of the late summer chorus that fills the air from this month into fall. 

    I learned that most of what we’re hearing is crickets, katydids, and cicadas. I picture a cricket as a chunky black insect shaped like a grasshopper. Those are the field crickets. 

Field cricket, genus Gryllus

In addition to their chirps, the background trill or hum we’re hearing at night comes from tree crickets, which look quite different.

Snowy tree cricket, Oecanthus fultoni

    As you might guess, it’s the male crickets that make the noise. They have three kinds of songs, a loud one for attracting females, a softer one for wooing a potential mate once she’s nearby, and an aggressive one for warning off other males. 

     Crickets and katydids make their sounds not with their mouths but with their wings in a process called stridulation. They rub one wing across a rough patch on the other, similar to running a finger down the teeth of a comb. The shape of the wings amplifies the sound. Females are looking for larger mates, and the male crickets can improve their chances by moving their wings faster, which makes them sound larger.

    It’s true you can gauge the temperature by timing chirps of the snowy tree cricket. The number of chirps counted in 14 seconds plus 40 equals the ambient temperature. I find it sad to hear slowing chirps in late fall as the last crickets get too cold to sing.

    Katydids get their common name from their song, which some listeners think sounds like “Katy did, Katy didn’t.” They make a buzz, “zip” or “zeep” sound. They look like large green grasshoppers with long antennae. They have ears at the joints of their long front legs.

Common true katydid, Pterophylla camellifolia-photo Lang Elliott

     

     Crickets and katydids don’t harm our plants. They eat small bits of plant material without doing noticeable damage. They may function as beneficials, eating insect eggs, larvae, or small insects such as aphids or scale insects (I’ll be glad to share as many of those as they want!).

    The most dramatic of the singing insect trio is the cicada, which makes a distinctive crescendo “zee-oo-zee-oo” lasting 15 to 30 seconds. These songs can be as loud as 120 decibels, painful for human ears. The males sing for mates by puffing out their abdomens and bending flexible ribs on parts called tymbals. Adults suck sap from woody plants, but without doing much harm.

Annual cicada, Neogtibecen linne

    This is the insect that drops its nymphs to the ground, where they burrow under and feed on root sap. Annual cicadas emerge the next spring. Periodic cicadas emerge together on 13- or 17-year cycles.

17-year cicada, genus Magicicada

    These interesting insects add to the late summer ambience without doing anything gardeners need to worry about. Nice to know.

Living fossil returns home

I first saw dawn redwoods (Metasequoia glyptostroboides) in 1995 when I was taking a course in identifying trees at the Arnold Arboretum. Entering the arboretum’s main gate, visitors come upon a grove of these magical trees growing beside a stream. When I had a chance to plant new trees two years later, there was no question but this would be one of them.

Dawn redwood in May, Willow Pond, Mt. Auburn Cemetery

    This species has an intriguing history. It was found in fossils dating back 165 million years to the Mesozoic era but was thought to have gone extinct at least 5 million years ago. In the early 1940s, Chinese scientists found living specimens in a remote area in Sichuan and Hubei provinces in southwest China. They communicated with colleagues in the U.S. and sent seeds to the Arnold Arboretum, whose director at the time, E.D. Merrill, distributed them to botanical gardens and arboreta around the world. These seeds grew readily in a wide range of conditions, and dawn redwoods became popular ornamental trees.

Dawn redwoods in fall at Wisley Gardens, Surrey-ukgardenphotos

    The stand of trees discovered in the 1940s, revered locally under the name of “water fir,” is now down to about 5,000 trees, having lost ground to conversion of the area to rice paddies. Fully grown trees can live to 265 years, reach trunk diameters of 7 feet, and grow as tall as 165 feet. The trees are legally protected, but all the cones are scooped up by people who want to try growing their own dawn redwoods. There’s no sign that the mature trees are reproducing anymore, so the international diaspora may be the only hope for survival of the species.

    Our dawn redwood came to us at about five feet tall. It’s since grown to at least forty feet high with a trunk 16 inches wide. The trunk is already showing the distinctive buttressing that gives the species some of its fairytale quality. 

Our dawn redwood has grown fast

The ferny leaves are soft, not like most waxy conifer needles. They begin the year a bright lime green and turn a rusty orange in fall before falling.

Soft, ferny leaves

    Dawn redwood is one of the few deciduous conifers, a group that includes bald cypress (Taxodium distichum), larch (Larix spp), and golden larch (Pseudolarix amabilis). 

Golden larch about to shed its leaves

Why deciduous? Apparently dawn redwoods grew so far north in Canada during a warm period in the earth’s history that they experienced polar light conditions: three months of unceasing sun in summer and total darkness in winter. They adapted by evolving from evergreen to deciduous.

Dawn redwood at Arnold Arboretum in winter-photo Glasser

    I like knowing that this tree was once common in my area—back when the dinosaurs roamed the earth, literally. This points out the complexity of defining native plants. Enthusiasts usually think of natives as plants that grew in North America before European settlement. But the moment Europeans set foot on our soil with foreign seeds stuck to their shoes is only a brief snapshot in the botanical history of the continent. I can rightly say that by planting a dawn redwood, I reintroduced a New England native.

 

Neonics' notoriety

Evidence keeps piling up against widespread use of neonicotinoid insecticides. Reacting to a critical review by its scientific branch, the European Union recently banned the use of the chemicals except in closed greenhouses.

Neonics harm bumblebees

Some of the bad news:
•    Populations not just of honeybees, but also bumblebees and solitary bees, important pollinators, are declining in many countries where neonics are widely used. If they don’t die, exposed bees have fewer queens and may be neurologically impaired, losing their navigational ability.
•    Neonics are found in water, soil, and wildflowers near fields of treated crops. Insects can contact the pesticides without visiting the crop plants.
•    Three out of four honey samples from around the world and 86 percent in North America contained neonicotinoids.
•    Neonics have been found in food, and claims that they’re harmless to vertebrates are losing conviction; for example, exposed sparrows lost weight and got lost during migration.

This swallowtail caterpillar's food could be contaminated

As with climate change, the science is complicated, and the pesticide industry is still saying there isn’t enough evidence that neonics are causing the bee die-off. An alarm sounded when a German study showed a 75 percent decrease in flying insects over a 25-year period, but this wasn’t attributed to neonics alone. Analysts opined that habitat loss and widespread use of pesticides were both major determinants. In the US, it’s thought that neonics may weaken insects’ immune systems, making them susceptible to epidemics caused by fungi and mites.

Honeybee on a black-eyed Susan

    What’s to be done? New systemic pesticides are already being introduced, but that hardly seems like a solution. Farmers in the UK objected to the European Union’s ban, saying the pests they needed chemicals for are still around. I hope farmers will transition toward methods that minimize pesticides and preserve insect habitat.

    On my tiny scale, I’m still trying to keep neonics out of my garden but recognize that I’m not fully succeeding. I bought only untreated seed this year—treated seed is the way neonics are often introduced into the commercial growing process, and they persist in tissues as the plants grow. My favorite garden center promises that they don’t use pesticides, but does that mean their plants are neonic free throughout the life cycle? In today’s nursery trade, seedlings change hands repeatedly.

I can't be certain this 5-year-old caryopteris is neonic-free

    I’ve fallen back on reproducing my own plants by spreading seed or making cuttings or divisions.  I got a new generation of purple coneflowers (Echinacea purpurea) by cutting off the flower heads of some organically grown plants in fall and scattering them in an area where I wanted more plants. Two years later, many new coneflowers are blooming.

Purple coneflowers are popular with bees

    To make my new bed, I dug out and transplanted wedges or whole offspring from existing perennials: variegated iris (Iris pallida), columbines (Aquilegia spp), dwarf goat’s beard (Aruncus aethusifolium), and goldenrod (Solidago spp). I’m growing some new bearberry (Arctostaphylos uva-ursi) from cuttings.

This hoverfly is another hardworking pollinator at risk

    Making new stock from my yard’s plants would exclude pesticides if I’m right that the plants started out untreated, but if not, I’m just perpetuating contamination.