Canada’s trees have developed some resistance to native diseases and insect pests. However, climate change has been facilitating more forest damage. For example, the native Mountain Pine Beetle (Dendroctonus ponderosae) used to be held in check because it was killed by extremely cold winter temperatures, which occur less frequently now than they used to. Additionally, in the last 125 years, the importation of live trees and untreated wood from other continents has brought in many pests that now threaten not just urban trees, but the integrity and survival of our wild forests as we know them. Likewise, the accidental importation of North American diseases and pests, such as the Pinewood Nematode (Bursaphelenchus xylophilus), threatens forests on other continents. The stories of just three threatened Canadian tree species are recounted below.
American Chestnut (Castanea dentata)
In the hardwood forests of eastern Canada and the United States, massive 35-m tall American Chestnut trees once grew. They were an excellent source of timber and produced edible nuts enjoyed by both people and wildlife. In some areas it was estimated that one of every four trees was a chestnut. Then, in 1904, the New York Zoo brought in livestock of Japanese Chestnut (Castanea crenata) trees that were infected with the fungus known as Chestnut Blight (Cryphonectria parasitica). This fungus damages the cells that transport water and sugar through the trees, eventually causing them to starve to death. The spectacular American Chestnuts had no natural resistance, unlike Asian chestnuts, and the disease quickly spread. By the 1940’s, four billion chestnut trees were dead, and their niches became occupied by other trees such as maples (Acer spp.) and oaks (Quercus spp.). American Chestnut still survives as a shrub sprouting from old roots but eventually all individuals succumb to the disease. In Canada, it is endangered and protected by the Species-at-Risk Act, 2002. However, there may be a way to bring this species back using modern technology: trees that appear to be blight-resistant have been bred by inserting a novel gene from wheat.
American Elm (Ulmus americana)
The beautiful fan-shaped American Elm tree became one of the most popular urban trees in North America; in the city of Winnipeg alone, there are more than a quarter of a million. These trees are also common in the wild, growing in hardwood and mixedwood forests along with poplars (Populus spp.), ashes (Fraxinus spp.), Manitoba maples (Acer negundo) and spruces (Picea spp.). In 1928 elm wood containing spores of Dutch Elm Disease (DED) (Ophiostoma novo-ulmi), a type of fungus, arrived in untreated wood destined for the furniture industry in Ohio. The fungus was spread by both native and introduced bark beetles, which tunnel under the bark of elm trees. By 1989, the fungus had destroyed 75% of all North American urban trees. DED reached Manitoba in 1975 but summer pruning bans, prompt removal of infected trees, prohibition of elm firewood transportation and treatment with pesticides and a vaccine helped Winnipeg protect its trees. Winnipeg is now the home of the largest surviving urban elm forest. However, unless these efforts are sustained, losses will mount and more trees will die.
Ash (Fraxinus spp.)
As DED began decimating North America’s elms, many communities began planting Green (Fraxinus pennsylvanica) and Black Ash (F. nigra) instead. However, these species are now threatened (Black ash was place on Canada’s endangered species list in 2018) due to the accidental importation of pests from other continents in untreated wood products (sound familiar?). The Emerald Ash Borer (Agrilus planipennis) arrived in Michigan from Asia in the early 1990’s, and was first sighted in Manitoba in 2017. This beetle feeds on the inner bark of a tree, eventually strangling it. Another pest, the Cottony Ash Psyllid (Psyllopsis discrepans), a type of jumping tree louse, was introduced from Europe, arriving in Winnipeg in 2017. The Psyllid damages the leaves of ash trees rather than the bark. This double whammy of pests will likely kill most of Winnipeg’s ash trees in the next decade and forever alter our wild ash forests. The negative impact on wildlife that rely on ash trees for food and shelter will be huge. Fortunately, some individual trees appear to be more resistant to the Emerald Ash Borer, and can help us breed insect-resistant stock.
How to Save a (Trees’) Life
There are many things we can do to help protect our trees.
1. Slow the Spread
Follow all biosafety protocols regarding importation of any plant or plant product. Buying locally grown trees and nursery plants, and locally produced wood mulch rather than imported products is the safest option. Consider buying and refinishing antique furniture, and using reclaimed or recycled wood for woodworking and construction projects instead of new wood. To be safe, don’t transport ANY firewood; burn local wood only.
2. Reduce the density
Planting monocultures of the same species may look nice (I love those green elm tree “tunnels” as much as the next person), but it is a recipe for disaster. Planting a greater diversity of tree species lets them “socially distance” from one another, reducing the likelihood of disease transmission and catastrophic tree losses within a short period of time. If you lose a tree in your yard, replace it with a different species than the ones surrounding it.
3. Improve tree health
Remember to prune trees properly when they need it, adhering to any relevant pruning bans. If you don’t know what you’re doing, contact a professional arborist (tree doctor) for help. Regular watering of young or vulnerable trees, and banding trees to reduce cankerworm infestations will also help your trees stay healthy.
4. Support scientific research
Scientific research that was started 43-years ago at an arboretum at Penn State may hold the key to saving ash trees as some appear to have natural resistance and can be used for breeding resistant stock. In Canada, the University of Guelph has been leading a breeding program for DED-resistant American Elm trees. The National Tree Seed Centre in Fredericton, New Brunswick stores seeds of Canada’s native trees, which can be used to breed resistant plants. In fact, the public is being encouraged to collect and send them wild ash seeds for their seed bank. But public support for research that doesn’t appear to offer any immediate benefit, is not always forthcoming. Real life is not like a Hollywood movie; scientists can’t conjure up cures to diseases overnight. It takes years of research to come up with solutions to new problems. Let your political representatives know you support publicly-funded science.
Trees provide us with so much-oxygen, shade, beauty, wildlife to admire and even food-that we need to give something back. You can report sick trees in Winnipeg by calling 311, the Canadian Food Inspection Agency or the Emerald Ash Borer hotline at 1-866-463-6017. If you lost a tree to disease or the tree-pocalypse storm in October 2019, consider planting a new one as soon as you can. Many Winnipeg greenhouses will even deliver plants right to your door this year. If you would like to see a tree planted on a city-owned boulevard or park, you can ask the city of Winnipeg to plant one. Remember the best time to plant a tree was 20 years ago. The second-best time is now. Enjoy your neighborhood trees this spring!
We humans tend to think that diseases affect only animals but plants suffer from them as well. Diseases are caused by microscopic animals (like parasitic worms), fungi, bacteria and viruses and they affect animals, plants, fungi and even some species of bacteria (viruses that infect bacteria are called bacteriophages). But it’s not just microorganisms that parasitize species; larger organisms do too. Some fungi are parasites of other fungi and some plants are parasites of other plants. One good example that you may have encountered while going for a walk in the woods is the Lobster Mushroom (Hypomyces lactifluorum). This species of fungus parasitizes other fungi, often the mushrooms of milk-caps (e.g. Lactarius), distorting the shape and resulting in the bright orange colour. Although some people enjoy eating these mushrooms, they could be poisonous if the mushroom that was parasitized was poisonous.
Another common parasite you may have encountered is Dwarf Mistletoe (Arceuthobium spp.). Mistletoes parasitize trees such as white spruce (Picea glauca), causing strange broom-shaped branches, often called “witches-brooms”. Mistletoes are actually flowering plants that cannot photosynthesize. Instead, they have modified roots that can tap into the vascular systems of other plants to steal their sap. To disperse their seeds, the fruits build up hydrostatic pressure, and then shoot the seeds into the air at speeds of up to a spectacular 80 km per hour! The seeds are covered in a gluey substance, which helps them stick to the bark of trees. The germinating seed sends its roots into the tree bark instead of the soil.
Parasites and diseases are what population ecologists call density-dependent causes of mortality; factors that only affect an individuals’ survival when populations are at high densities. Other density-dependent factors affecting plant survival include: competition for resources, such as water, light and soil minerals, and intense herbivory (usually by insects). In general, density-dependent causes of mortality are biotic, that is, caused by other organisms. Density-independent factors of mortality are usually abiotic (not alive) or environmental: forest fires, drought and volcanic eruptions that bury vegetation in lava are a few examples.
There are plenty of plant parasites and diseases that evolved right here in North America. However, most native plants have evolved methods to resist these organisms to some degree so it is not always fatal to the plant, unless it is in a weakened state. During droughts for example, trees are much more likely to die of a disease. Since the colonization of North America occurred, species of diseases that were not native to this continent have been accidentally introduced, typically with dire consequences. In my next blog, I will be discussing how three species of native Canadian trees (American Chestnut, American Elm, and Green Ash) are being negatively impacted by introduced diseases, and how we can change our behaviour to protect our forests, both wild and urban.
One of the most significant contributions that America’s Indigenous peoples have made is with respect to agriculture. Many of our most beloved foods (e.g. chocolate, potatoes, corn) are native to the Americas, being initially cultivated or domesticated by Indigenous farmers.
Indigenous agriculture has a long history with the most recent archaeological evidence suggesting it has been practiced in the Americas for at least 10,000 years, almost the same time length of time as in the Fertile Crescent of the Middle East. There were five agricultural centers of origin (i.e. places where multiple species were cultivated or domesticated) in the Americas: three in South America and one each in Central and North America (Table 1).
Table 1. Crop plants cultivated or domesticated in the Americas by Indigenous peoples.
Cereals & pseudo-cereals: Amaranth, chia, goosefoot, knotweed, little barley, maize (corn), maygrass, quinoa, sunflower and wild rice.
Legumes & nuts: American chestnut, black walnut, Brazil nut, cashew, common beans (green, black, pinto, navy, etc.), hickory, lima beans, peanut, pecan, scarlet runner beans and tepary bean
Roots & tubers: Arrachacha, arrowroot, camas root, cassava, hopniss, jicama, leren, mashua, oca, potatoes, sunroot, sweet potato and yacón
Fruits: Acai, avocado, blueberry, chayote, cherimoya, cranberry, feijoa, guava, huckleberry, papaya, passionfruit, peppers, persimmon, pineapple, prickly pear, raspberry, squash, strawberry, tomato and tomatillo
Spices, beverages & flavours: Achiote, chicle, chocolate, coca, maple, tobacco, vanilla and yerba mate
The Andes was where the earliest crops (e.g. potatoes (Solanum spp.) were domesticated about 10,000 years ago. Corn (Zea mays) and squash (Cucurbita spp.) domestication began in Central America 8,700 years ago and beans (Phaseolus spp.) shortly after. In the eastern U.S., agriculture was being practiced 3,800 years ago.
Spread of Indigenous Crops
Crops that were part of the “Eastern Agricultural Complex” in the southeastern U.S. included a variety of nutritious seed plants such as sunflower (Helianthus annuus), goosefoot (Chenopodium berlandieri), bottle gourd (Lagenaria siceraria), marshelder (Iva annua), little barley (Hordeum pusillum) and squash (Cucurbita pepo). Other domesticates that followed include ragweed (Ambrosia trifida), pigweed (Amaranthus spp.), and knotweed (Polygonum spp.). After ~200 BCE (before common era) corn, beans and squash from Mexico were brought to this region and cold-tolerant varieties (e.g. Northern Flint) bred. The productivity of corn was so high that the traditional seed crops fell out of favour and were gradually abandoned. Sunflowers are the only crop plant left from the original Eastern Agricultural Complex that is still grown today. The other species have largely reverted to their wild state. Some of these species are considered “weeds” in croplands today even though they are still edible.
Agriculture Spreads to the Northern Plains
Most people are surprised to find out that Indigenous people were practicing agriculture in the Dakotas and Manitoba in the early 1400’s. In 1986, Manitoba Museum Curator Dr. Leigh Syms unearthed evidence that corn, beans, squash and sunflowers were being grown as far north as Lockport during that time (http://www.mhs.mb.ca/docs/mb_history/31/firstfarmers.shtml). These three plants were traditionally planted close together with the beans climbing up the corn stalks and the squash helping suppress weeds. Raising plants in this manner improved the fertility of the soil as beans harbour special bacteria that turn gaseous nitrogen into a form available to all plants (ammonium or nitrate). Together these three plants were the foundation of a healthy, vegetarian Indigenous diet. Sunflowers, often called the fourth sister, were typically grown along the edges of Indigenous fields, and provided an additional source of fat and protein. Climatic changes which resulted in a shorter growing season and population losses due to diseases introduced after European contact in 1492, may have resulted in the abandonment of the cropland in Manitoba.
After Europeans arrived in the Americas, crops from the “Old World” (e.g. wheat, barley, oats) were brought here while American crop plants were transported to Africa, Asia and Europe; this process was known as the Columbian Exchange. Sometimes the new American foods were embraced readily (e.g. beans) but others were not, particularly those in the nightshade family (e.g. tomatoes, potatoes and peppers). In Europe, nightshade plants are mainly poisonous rather than edible so people were suspicious of them. In France, people initially rejected the potato (they thought it caused leprosy) but King Louis the 16th was convinced by the agronomist Antoine Parmentier that it was a good food plant to grow. Apparently, Parmentier had potatoes planted in the Kings’ gardens and then set guards around them to prevent thefts (although the guards were told to accept bribes). This reverse psychology apparently worked and after some people got their hands on the potato, its cultivation spread. Many American crops are now an integral part of European, African and Asian food culture. However, introduction of these new foods did cause some problems.
The Importance of Indigenous Food Culture
The knowledge of how to prepare American foods did not always accompany the food, possibly because Europeans of that time period were generally disdainful of Indigenous knowledge, customs and food culture. Unfortunately, this attitude ended up causing a lot of unnecessary deaths.
People in warmer parts of Europe and Africa readily adopted corn because it was so much more productive than other crops. But after doing so a strange new disease began affecting poor people who were relying mainly on corn for food. This disease is pellagra, a condition that causes dermatitis, diarrhea, dementia and eventually, after four or five years, death. Physicians were confused about this new diet-related disease because they noticed that even though Mexicans ate a lot of corn, they rarely got pellagra. The answer to this puzzle was in Indigenous food culture. Corn was often softened by soaking it in an alkaline solution. This softened corn, known as hominy, is then eaten as is, or dried and ground to make masa, the flour used to make tortillas and tamales among other things. This process, known as nixtimilization, increases the bioavailability of niacin (vitamin B3) and tryptophan in corn. Pellagra is caused by a deficiency in niacin and tryptophan in the diet. In Europe, Asia, Africa and even among poor non-Indigenous people in the southern U.S. , people were just drying the corn, grinding it up and cooking it into dishes like cornbread or polenta. Eaten in this manner, with no other foods containing niacin in the diet, pellagra is the result. Another aspect of Indigenous food culture that was not taken to heart was the custom of eating corn with niacin-containing beans, resulting in a balanced diet.
Food Culture and Reconciliation
Racism and the intellectual and cultural arrogance that accompanies it, has caused tremendous human suffering. Colonization and the discouragement of traditional Indigenous agricultural practices and cooking, resulted in the near loss of ancient varieties of crop plants such as quinoa, as well as the memory of how these foods should be grown and prepared. It is heartening to see Indigenous peoples embracing their gastronomic legacy by planting three sisters gardens, writing cookbooks featuring pre-colonial foods (e.g. The Sioux Chef’s Indigenous Kitchen, Cooking with the Wolfman, and tawâw) and opening innovative restaurants (e.g. Ishkode Indigenous Pop-up https://aptnnews.ca/2019/10/25/indigenous-pop-up-showcases-traditional-eats-in-a-modern-world/). Part of reconciliation is simply accepting that Indigenous culture is valuable. Another part is supporting the efforts of Indigenous peoples in keeping their culture alive. Food has a way of bringing people together so maybe the path forward is to sit down and share a meal together.
Many plants use the wind to disperse their seeds. But what if a plant lives somewhere that isn’t very windy? How do they encourage their children to “launch”? Many plants decided to take advantage of animals’ mobility. One way plants do this is by growing little hooks or stiff hairs on the fruits that readily catch onto the fur or feathers of an animal when they are ripe. The fruits are carried for possibly hundreds of kilometers before getting rubbed off. The fruits of many North American prairie plants are adapted for transport on bison fur.
But what if you live somewhere where there aren’t a lot of big, hairy animals. As it turns out there are ways to get smaller creatures to transport your seeds as well. You do it by producing a substance that the animals find irresistible: fleshy fruits.
Plants that live on the forest floor have it pretty tough because there is very little wind and there usually aren’t big herds of animals hanging around. So some early flowering plants, including violets, bloodroot and Dutchman’s breeches, adapted to use insects to disperse their seeds instead. The seeds of these plants have fatty structures attached to them called eliosomes. After the seeds fall off the parent plant, ants carry them to their nests, remove the eliosomes and then abandon the seeds. The plant seeds sprout readily in the disturbed habitat.
Plants with fruits that ripen late in the year often rely on flocks of migratory birds for dispersal. Birds are particularly good seed dispersers because they lack teeth, typically swallowing fruits whole. In bird stomachs, the fleshy part of the fruit is digested but the tough seeds usually excreted intact. In fact, the seeds of many plants need to pass through the guts of animals before they will even germinate. However, some fruits are toxic to mammals (like rodents) but not birds. This is because mammals tend to chew the seeds as well as the fleshy parts, killing the baby plant. For that reason, berries that birds can eat are not always safe for people! Therefore, make sure you have correctly identified and researched the toxicity of any fruit before you eat it.
There’s one more creature that plays a huge role in the dispersal of seeds: people. Humans are by far the best seed dispersers ever. We don’t just move seeds a few kilometers; we move them to entirely new continents, creating the exact kinds of conditions the plants like to grow in. Humans like to think that we domesticated plants and forced them to do our bidding, but it is entirely possible that it was the other way around; perhaps it was the plants that domesticated us.
Just like all creatures, plants want to reproduce themselves. But they typically don’t want their offspring hanging around for too long, eating all the food in the fridge and drinking all the beer. But plant babies living on the land can’t move on their own, so how is an exasperated plant parent going to get their children to leave the nest?
Instead of producing swimming babies like algae do, the very first land plants produced special structures called spores. These spores, which grow into tiny plants, are small enough to be carried away easily by the wind, just like dust. For about 80 million years or so, the only plants on land were species that produced spores: club mosses, horsetails, ferns and mosses.
About 390 million years ago in the mid-Devonian, a new group of plants evolved that were capable of growing very quickly. They are known as the seed plants, and they have dominated life on land for many millions of years. But what exactly is a seed anyway and how is it different from a spore? A spore consists of only one cell; it’s basically a naked baby. For that reason, spore-producing plants aren’t very good parents; they just boot out their kids with nothing to eat and no clothes on. A seed on the other hand consists of three things: a baby, a bottle to feed the baby and clothes to protect the baby.
The first seed-producing plants were the gymnosperms (which means “naked seed” in Latin). They produced multiple babies in structures called cones. But the seeds of these cone-bearing plants are quite heavy compared to the spores of ferns, and initially they may have fallen right under their parent. Plants will obviously not grow very well in the shade of their parent, so any kind of structure that would help the seed move a little further away was advantageous. That’s why many cone-bearing plant seeds evolved a thin wing that increases wind resistance and helps the seed glide further away.
The development of seeds was a real game changer because plant babies were way more likely to survive with a food source. There was just one problem: animals. Seeds represented a new source of food for them and they eagerly indulged.
Around the same time mammals evolved, in the Jurassic period about 160 million years ago, yet another group of plants evolved that had an advantage over the cone-bearing plants: they protected their young by enclosing them in fruits. In many species, the fruit also functions as a mode of transportation, essentially a kind of baby carriage. In habitats that are open and windy, like grasslands, many plants continue to use wind to disperse their babies. The elaborate shapes of the fruits (many functioning like parachutes), enables the seeds to fly for much longer distances than the simple gliding seeds of the cone-bearing plants.
What if a plant lives somewhere that isn’t very windy though? What do they do? Stay tuned for part 2 of “The Perils of Plant Parenthood” to find out.
This summer I spent some time doing what badgers do: digging. What was I digging for? Plant roots. Usually when I collect plants for the Museum I take only a few stems of the above ground portion so that the plant doesn’t die. But this time I needed roots: long ones. I thought that digging up roots would be pretty awful but the soil was sandy, the weather co-operated and, thanks to the presence of two co-workers, it did not take as long as I thought. The worst part was hauling all our gear over the sand dunes to the spot where we would be digging. So why did I need roots? They are for a new Museum exhibit.
In late 2020, the Museum will be opening our new Prairies Gallery. This gallery will represent years of work by the staff at the museum, in particular the Curators and conservation staff. One of the exhibits that I am involved in is a new case illustrating life below the surface of a native prairie. In our original gallery we have a wonderful specimen of grass showing the full extent of its root system. You’ve probably seen it: it’s a pretty impressive specimen. There’s just one problem: it is not a native species. It’s actually a Eurasian species called crested wheatgrass (Agropyron cristatum). It was brought to Canada in the 1930’s to help prevent the soil from blowing away during the droughts of that decade.
So we decided to display some native plant root systems for a new case near the entrance to the gallery. Although we are growing a few specimens in a greenhouse for this exhibit, one of the flowers we wanted was not doing well in that environment. After remembering that there are plants with exposed roots on the sand dunes in Spruce Woods Provincial Park, I arranged to excavate one of the common species, white prairie-clover (Dalea candida), with the permission of Manitoba Sustainable Development.
During a reconnaissance trip in July, I found a nice specimen that was eroding out of the dunes and in all likelihood would soon die. After taking some pictures and making a few notes, we channelled our inner badgers and began digging it up. In the end we obtained an impressive 160 cm piece of root along with the flowering stems. Although there were more fine roots lower down, the part we dug up is longer than we can even fit in the case so we left them behind. Since the site was a bit of a mess afterwards, we filled in the hole and patted the dune back to its previous contours. I was happy that a heavy rain that evening obliterated all evidence that we were ever there. The plant is now being pickled by the Diorama and Collections Technician in our secret proprietary solution (even I don’t know what’s in it!) to keep it fresh-looking and bendy! Eventually it will be painted and mounted in its permenent home next fall.
So what is happening with the old crested wheatgrass plant? Don’t worry, it will still be on display but reinterpreted for its role in soil stabilization during Great Depression.
Water-saturated bogs and burning hot, cactus-covered sand dunes are not the kinds of habitats that you would normally expect to find near each other. But on a recent trip to Canadian Forces Base Shilo, I was surprised to find just that!
In July, I was able to visit this restricted area to collect plants as part of a research project. We went to a part of the base that I have never been to before: Sewell Lake. I was expecting the kind of vegetation that you typically find along a prairie wetland: cattails, sedges and bulrushes. What I discovered was an area that looked more like a bog in the middle of the boreal forest. Thick mats of moss floated on top of water and threatened to swallow you up if you weren’t careful. Aquatic plants like water calla (Calla palustris), buckbean (Menyanthes trifoliata) and marsh cinquefoil (Comarum palustre) lined the shore. Even pitcherplants (Sarracenia purpurea) have been found in the deepest areas of the bog. Turtles swam in the water and all sorts of amazing insects were everywhere. It was truly unusual and a biologists’ delight.
But what was the oddest thing was that not even 50-m away from this wetland there was a huge sand dune that ran parallel to the lakeshore. While walking along the ridge of this dune, I encountered rare plants that you only find on the driest of prairies: prickly pear (Opuntia fragilis), and pincushion cactus (Coryphantha vivipara), winged pigweed (Cycloloma atriplicifolium), American bugseed (Corispermum americanum), and the lovely hairy prairie-clover (Dalea villosa). Our guide told us that there are an astounding 450 species of vascular plants on the base lands, an impressive number when you consider that there are only just under 1700 plant species in the whole province.
So, on the one side there were plants that were adapted to dealing with an excess of water and on the other plants that dealt with an almost complete lack of it. So how do plants deal with these conditions? They possess completely different internal structures. In wet habitats, the biggest danger to plants is a lack of oxygen. You’re probably puzzled. Don’t plants need carbon dioxide? Well yes they need carbon dioxide for photosynthesis, which occurs mainly in the leaves, but they also need oxygen to break down the sugars they create to obtain energy for growth. This isn’t a problem for leaves and roots living in soil with lots of air pockets but it is a problem in water-saturated soils. To get oxygen to the roots, many aquatic plants have special tissue called aerenchyma–tissue with big air tubes in it–which functions a bit like a snorkel. The plant moves oxygen from the holes in their leaves, called stomata, all the way through these tubes to the roots. Problem solved! Regular dryland plants don’t have aerenchyma, which is why over-watering your houseplants can kill them; they basically suffocate.
In contrast, for plants in dry habitats like sand dunes, obtaining and retaining water is the problem. To obtain water they either grow roots deep enough to reach the water table, or absorb water quickly when it does rain by growing extra root hairs. To prevent water loss, they may possess thick “skin” that prevents evaporation; cacti are a good example of this. As well, they can prevent evaporation of their water by keeping their air holes (stomata) closed during the heat of the day, opening them to obtain gases at times when it isn’t so hot.
The structural uniqueness of plants is not always appreciated, recognized or understood by non-botanists. But really the difference between plants in bogs and sand dunes is like the difference between a fish and a camel!
Now that the weather is nice and warm, you’re probably seeing pollinators flying about. The main insect pollinators in Manitoba in order of decreasing abundance are: bees, flies, butterflies, moths, wasps and beetles. If you’d like to tell them apart, there are a few key features you need to look for. First off, count the number of wings. Are there four or just two? What is the texture like: membranous, hard or covered in tiny scales? Second, look at the body: is it smooth or covered with hairs? Does the area where the chest (thorax) connects to the belly (abdomen) get really narrow? Third, check out the antennae. Are they long, short, smooth or feathery? Lastly, is the insect intentionally gathering pollen on its legs or just drinking nectar? Asking these simple questions will help you identify your pollinator.
People are sometimes frightened by bees thanks to stories about “killer bees” but our native ones are actually pretty timid because stinging will kill them. They are usually so intent on feeding that they will ignore you completely. The main bees you will find in Manitoba are bumblebees (Bombus), honeybees (Apis), leafcutter and mason bees (Megachilidae), sweat bees (Halictidae), polyester bees (Colletidae) and mining bees (Andrenidae). Bees like a wide range of plants but seem to prefer yellow, purple or blue flowers. Longer tongued bumblebees prefer tubular plants like legumes.
The key characters of bees include:
* Four lacy (membranous) wings;
* Pronounced waists;
* Long antennae;
* Eyes at the side of the head;
* Lots of branched hairs;
* Pollen-carrying structures like leg baskets (bumblebees & honeybees), leg hairs (sweat, mining and digger bees) or belly hairs (leaf-cutter bees);
* Straight, long- or short-tongues;
* Body colour ranging from pale to dark yellow, orange or white and black striped, rusty brown and black, or shiny blue and green.
Wasps are closely related to bees but rather than being complete vegetarians, they typically feed their young meat (i.e. usually other insects). Since wasps can sting multiple times, they are usually more aggressive than bees. Most wasp species will not bother you but paper wasps, hornets or yellow jackets (Vespidae) can be very territorial so give them a wide berth. Wasps have short tongues so they tend to visit flowers that are open or have short floral tubes. Wasps have:
• Four lacy (membranous) wings;
• Pronounced waists;
• Long antennae;
• Eyes at the side of the head;
• No body hair or unbranched hairs only;
• No pollen-carrying structures;
• Straight short-tongues;
• Body colours that are often bright yellow and black or brown striped, or various solid colours (e.g. black, brown, green).
Surprising to many people is the fact that a wide diversity of flies are pollinators. In fact they are second in importance to bees (take that butterflies!). Flies tend to like open (not tubular) flowers that are white or yellow. Flower flies (Syrphidae) often look similar to bees with yellow or orange and black stripes while bee flies (Bombyliidae) look like tiny pussy willow catkins with wings. Soldier (Stratiomyiidae) and blow flies (Calliphoridae) are often bright green in colour and not very hairy, while parasitic (Tachinidae) and Muscid (Muscidae) flies look very similar to house flies with black or grey bodies and long, coarse hairs. The key ways to tell these insects apart though are:
• Two wings only;
• No waist;
• Large eyes near the front of the head;
• Short, club-like antennae;
• Unbranched hairs, if any;
• No pollen-carrying structures;
• Straight short or long tongues.
Butterflies are pretty easy to tell apart from bees, wasps and flies because they have large wings. But telling them apart from moths can be a bit more difficult. Typically butterflies are active only during the day and have:
• Four large, brightly coloured wings;
• Wings that fold upright when not in flight;
• Long antennae typically with a bulb at the tip;
• Long, curled tongues.
As they have fairly long tongues, butterflies often prefer flowers with long tubes like bergamot (Monarda fistulosa). But smaller butterflies, like skippers (Hesperiidae), often like flat topped asters like black-eyed Susan (Rudbeckia hirta) and Gaillardia (Gaillardia aristata).
Although moths are typically active only at night (nocturnal) a few species forage during the day (diurnal) like hummingbird clearwing moths (Hemaris). Nocturnal moths prefer tubular flowers that are white but diurnal moths will visit brighter coloured plants, like hoary puccoon (Lithospermum canescens) as well. You can tell moths apart from butterflies by their:
• Four large, often duller coloured wings, sometimes with “eye spots”;
• Wings that stay flat and out to the side when not flying;
• Long antennae that are often feather-like not clubbed;
• Long, curled tongues.
Beetles are not the most common pollinators but there are a few species that will feed on the nectar of flowers that are flat, like woolly yarrow (Achillea millefolium). Beetles have:
• Four wings: two membranous, two hard;
• Short or long antennae;
• No hairs;
• Short tongues.
Happy pollinator watching!
The loss of biodiversity and plight of wild pollinators has been all over the news lately. If you’re interested in doing something to make life easier for these creatures, you might want to consider making your garden more pollinator friendly this year. Pollinators have three basic needs: food, nesting/breeding habitat and shelter.
The best thing you can do is grow at least some native plants in your yard. Native plants have the correct flower shape to fit the local pollinators and typically produce highly nutritious nectar and pollen. Cultivars of native plants, like bee balm (Monarda), and Echinacea (Echinacea) may be OK, but some research indicates that they may produce lower quality nectar and be less frequently visited than native species (https://www.humanegardener.com/flower-power-a-qa-with-annie-white/). Cultivars that are highly modified (e.g. double bloomed species), or lack nectar and pollen (e.g. sterile hybrids) are useless for pollinators. To provide a regular food supply, ensure you have selected a sequence of plants that flower all through the growing season. Helpful ecoregional planting guides have been created by Pollinator Partnership Canada and can be found here: https://www.pollinator.org/guides-canada. Good plant choices for southern Manitoba are noted below.
Flowers for spring insects
Shrubby cinquefoil (Dasiphora fruticosa), strawberries (Fragaria), three-flowered avens (Geum triflorum), native or domesticated cherries and plums (Prunus spp.), wild roses (Rosa acicularis), native or domesticated raspberries (Rubus), meadowsweet (Spirea alba), native violets (e.g. Western Canada violet (Viola canadensis)), and Alexanders (Zizia) all bloom in early May or June. Queen bees, butterflies and/or flower flies will visit these species. Pansies are pretty but typically the wrong size for native pollinators.
Flowers for summer insects
Wild legumes like prairie-clover (Dalea), leadplant (Amorpha canescens) and Indigo bush (Amorpha fruticosa), as well as giant hyssop (Agastache foeniculum), milkweeds (Asclepias), fleabanes (Erigeron), wild mint (Mentha arvensis), obedient plant (Physostegia virginiana), black-eyed Susan (Rudbeckia hirta) and Culver’s root (Veronicastrum virginicum) are good choices for summer. They will attract all kinds of bees, butterflies and flower flies.
Flowers for fall insects
Native composites such as coneflower (Echinacea), blazingstar (Liatris), white aster (Oligoneuron album), goldenrods (Solidago), and asters (Symphyotrichum) are great for fall bees.
Flowers for hummingbirds
To attract hummingbirds specifically, tube-shaped flowers that are red, pink or orange are good choices. Grow plants like wild columbine (Aquilegia canadensis), fireweed (Chamerion angustifolium), wild iris (Iris versicolor), western red lily (Lilium philadelphicum) and wild bergamot (Monarda fistulosa) to attract them, and consider putting a hummingbird feeder nearby for extra nourishment.
Pollinators need safe places to build their nests. However, different pollinators have different needs. Some bees prefer bare, sandy soil while others nest in tunnels in wood or plant stems. By not mulching all of your bare soil, especially in sunny spots with south facing slopes, you can provide habitat for ground-nesting bees. You can create artificial nesting areas for cavity nesting leaf-cutter and mason bees by building a bee condo (https://www.chicagobotanic.org/plantinfo/building_bee_nesting_block) or hanging some hollow stems like bamboo, in bundles above the ground. Bumblebees prefer nesting in small cavities or under piles of leaves. To attract butterflies to breed, you must provide them with their larval host plants, often native flowers or grasses (http://www.naturenorth.com/butterfly/english/06%20host%20and%20nectar.html). Hummingbirds will nest in small trees, often using milkweed and thistle down, moss and lichen for their nests.
Pollinators need places where they can spend the winter or undergo metamorphosis. In general, pollinators like “messy places” like tall clumps of grass, bushes, and leaf, rock or wood piles. Identify an area in your yard that you don’t use regularly and designate that as your pollinator “messy place”. Leave small wood piles there and in fall, rather than raking up every last leaf, create a leaf pile there. Another thing you can do is delay some of your yard clean up till spring. Instead of pruning all your perennial flowers and throwing the dead stems in the compost, leave them standing up until spring. This dead vegetation will help to insulate overwintering queen bees and butterfly larvae from the cold.
Happy gardening and good luck with your project! In my next blog, I’ll be giving a crash course in how to identify all those fascinating little pollinators that will be coming to your new pollinator friendly yard.
I personally feel a little sorry for plants. When plants want to have sex they can’t just go to a bar to meet someone; they are stuck in the ground. So what’s an amorous plant to do?
For most of the earth’s history plants lived in water. When they wanted to have sex they just released their sperm into the ocean where it would swim around for a while before fertilizing some eggs. Pretty simple. But as the oceans got crowded some plants looked with envy at the land, where there was plenty of room to grow and plenty of sunlight for photosynthesis. So about 470 million years ago (mya) in the Ordovician period, some enterprising young plants decided to head for the hills. These plants were mosses, ferns, club-mosses and horsetails.
What most people don’t know about these plants is that they still need water to have sex. For that reason they are actually the botanical equivalent of amphibians. They can live on land but they still need water for reproduction. During wet times of the year, these plants release tiny sperm into the environment that swim through the water on the forest floor to fertilize the eggs of another plant.
For about 80 million years all the plants on land still needed water to complete their life cycles. But it started to get a little crowded in the swamp. Fortunately, there was still a lot of land available where no plants grew. The only problem was, it was too dry. About 390 mya in the mid Devonian some plants looked to the skies for inspiration and noticed something interesting: wind.
A few adventurous species decided to release their sperm into the air all wrapped up in a water-tight, yet aerodynamic little package, kind of like a tiny ping pong ball. This structure is called pollen and the first plants to make pollen were the gymnosperms, better known as conifers or evergreen trees. Gymnosperms are the botanical equivalent of reptiles, which were the first animals to no longer need water for reproduction.
About 125 mya yet another group of plants evolved and they had a distinct advantage over the gymnosperms: they could reproduce a lot faster. Gymnosperm reproduction takes a long time: about 15 months for most species to produce a ripe seed. In contrast, some flowering plants can complete their life cycle in a just a couple of months. The very first flowering plants also used wind for reproduction.
Wind pollination is fine and dandy but it can be fairly wasteful; most of the pollen produced just lands on the dirt and dies. Then about 100 mya an enterprising group of insects saw an untapped market for their services; they would open a plant dating service for all those lonely trees–let’s call it “Timber”. In exchange for a few grains of pollen, which probably would have died anyway, the insect would move pollen from one flower to another. It was a win-win situation! Eventually, some plants started producing a sweet beverage called nectar to “pay” the insects in order to reduce pollen losses even further. Wasps and beetles were some of the very first insect pollinators.
As with most businesses, sometimes the employees don’t get along. Although wasps drink nectar from plants, they also eat meat, mainly in the larval stage. Now, one group of wasps found that they preferred a strictly vegetarian diet. They decided to split from their colleagues at “Timber” and form their own dating service; let’s call it “Bumble…bee”.
Bees are wasps’ vegan cousins and because they rely exclusively on plant nectar and pollen to survive, they are among the most faithful and effective pollinators in the world. In Manitoba over half of all pollinator visits in the prairies and parklands are performed by bees. It is because bees are such good pollinators that scientists have been so worried about declining bee populations. Although we don’t always notice pollinators, they fertilize about 87.5% of the worlds’ flowering plants (Ollerton et al. 2011) so the loss of our planet’s pollinators would truly be a disaster.
If you think your sex life is complicated, you don’t have anything on plants. Some plants have separate males and females just like people (e.g. buffalograss (Buchloe dactyloides), salt grass (Distichlis stricta), willows (Salix spp.), Manitoba maples (Acer negundo), etc.). But some of these plants, like sweet gale (Myrica gale), can switch their sexual orientation from year to year; female one year, male the next. Most plants are hermaphrodites, producing both sperm AND eggs. Furthermore, plants can reproduce themselves without even having sex. Some plants can self-pollinate, or even skip the pollination process altogether and grow a cloned seed. The pads of prickly pear cactus (Opuntia spp.) can detach and form completely independent plants-essentially little clones. This would be like you detaching your arm and having it grow into a clone of yourself.
Pollen is everywhere: in the water, in the sky and covering many of the animals. As pollen grains contain sperm and germinate when they land on the stigma of a flower, they are essentially tiny, little male plants. This spring, when you’re walking outside and you see pollen falling around you I want you to remember that sometimes it really does rain men!
Ollerton, J., R. Winfree, and S. Tarrant. “How many flowering plants are pollinated by animals?.” Oikos 120.3 (2011): 321-326.