The Perils of Plant Parenthood, Part 1 - Wind

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.

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.

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 the 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.

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!

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.

Great web pages with image of pollinators can be found at BugGuide, here, and Xerces Society, here.

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 (Learn more here). 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. 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), lilac-flowered beardtongue (Penstemon gracilis), and wild bergamot (Monarda fistulosa) to attract them, and consider putting a hummingbird feeder nearby for extra nourishment.

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.

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!

Reference:

Ollerton, J., R. Winfree, and S. Tarrant. “How many flowering plants are pollinated by animals?.” Oikos 120.3 (2011): 321-326.