What’s that stuff on my tree? A guide to Manitoba’s lichens

Lichens grow in the patterns they do to maximize the amount of light they intercept; some species look like tree branches (called fruticose = branch-like lichens) for this reason. Other lichens are leaf-like (i.e. foliose), or crusty (i.e. crustose). Some lichens living in really harsh environments (like the Antarctic) are cryptoendoliths, meaning that they live inside the rock, penetrating the tiny spaces in between rock crystals.

In the prairies, lichens often grow in hot, sunny habitats, such as sandy soils, and on glacially-deposited rocks. They are also common on fenceposts and abandoned human artifacts, like collapsing homesteads and rusty ploughs. In forested areas, lichens are common, growing on trees, as well as mossy, forest floors. In the Canadian Shield, rock outcrops are often almost completely covered by lichens. In urban areas, lichens are sometimes found on old buildings, like the legislature. Different species grow on these different substrates (hardwood vs. softwood, sandy soil vs. clayey soil, granite vs. limestone) so make sure you record this information when trying to identify lichens.

Since they don’t need soil, lichens are some of the first organisms that begin growing after large disasters wipe out all vegetation in an area. They are often the first to arrive after hot fires or mining activity (such as sand, gravel and coal mining). Acids in the lichens break down rocks, contributing to soil formation. Lichens can completely desiccate when it is dry, growing again when it rains. Due to this periodic desiccation, lichens tend to grow very slowly, reaching extremely old ages. Some lichens can be aged the way trees are: by counting their growth rings. Some lichens (i.e. yellow-green map lichens) have been dated as being over 8,600 years old.

Lichens reproduce themselves vegetatively, by breaking off into tiny pieces, and both sexually and asexually. Sexual fruiting bodies of various kinds (e.g. pycnidia, asci, apothecia etc.) are produced by the fungus. They release small, single-celled spores which germinate into new, partner-less fungi. These tiny fungi must find free-living alga to become lichens again. To allow both the fungus and the algae to disperse together, lichens also produce asexual propagules, usually at the branch tips, of various kinds (e.g. soredia, isidia, pycnidia etc.). These tiny clusters of cells, once dispersed, often by wind, will grow into a new lichen.

A few of the most common lichens in southern Manitoba are described below:

More lichen information can be found in this nifty little booklet available on-line (https://www.muskokawatershed.org/wp-content/uploads/LichenID.pdf) but if you are really serious about lichens I recommend investing in Irwin Brodo’s Lichens of North America.

When the Museum opens to the public again, our visitors will be in for a pleasant surprise. The very first of our nine galleries, now called the Welcome Gallery, has been completely renovated. The much-loved Bison diorama is still there, but the exhibits surrounding it are all different. Originally built in the 1970’s, this gallery definitely had a dated vibe to it that needed to change. Further, it was no longer doing its job as an effective introduction to the province of Manitoba or to the Museum’s galleries.

The role that First Nations, Inuit and Métis peoples played in the settling and formation of the province of Manitoba is now described in several places in the renovated gallery, including a beautiful new exhibit on treaties. This exhibit was created in cooperation with the Treaty Relations Commission of Manitoba, and features the medals, pipes and pipe bags associated with these agreements. It demonstrates the fact that the Museum is committed to working with Indigenous peoples to accurately tell the history of Manitoba.

Another prominent component of the gallery is a new wall projection depicting 18,000 years of Manitoba history in two minutes! The Museum’s seven Curators all worked together on this video, which portrays, among other things, melting of ice age glaciers, changes in vegetational communities (i.e. biomes) over time, migration of Indigenous peoples into Manitoba, migration of settlers after confederation with Canada in 1870, and predicted future temperatures due to climate change.

Curators pulled out many candidate specimens and artifacts when deciding what to put in the new gallery introduction case.

As a scientist, I was disheartened that the old Orientation Gallery did not highlight the fact that this Museum has scientific collections and does research. The new Welcome Gallery does a better job of explaining this, allowing us to display and depict some of Manitoba’s fascinating wildlife. In particular, the new Discovery Room exhibit, The Museum’s Collection Illuminated: Celebrating 50 Years, highlights specimens and artifacts collected by, or donated to, the Museum. A slide show gives visitors a peak into the lives of the Curators and Collections staff that brought this new gallery to life.

This giant puffball fungus, donated to the Museum many years ago, is now on display in the Discovery Room.

One of the most impressive plant specimens at the Manitoba Museum is a huge, preserved grass that shows the entire root system. I think the reason everybody likes this specimen is that it provides a perspective that no one ever has: what a plant actually looks like under the ground. There was just one problem with that grass: it’s not actually a native species. It’s a Eurasian species called Crested Wheatgrass (Agropyron cristatum) that was brought to Canada and widely planted in the 1930’s. During our planning for the new Prairies Gallery, the Curators strongly felt that visitors needed to see native species of plants when first entering the gallery. The process to collect plants for this exhibit was previously described in “I once caught a plant that was this big”.

In addition to the tap-rooted White Prairie-clover (Dalea candida), the display case includes a specimen of Manitoba’s Provincial grass, Big Bluestem (Andropogon gerardi) and a June Grass (Koeleria macrantha). White Prairie-clover relies heavily on associated microbial organisms to obtain adequate nutrition; mycorrhizal fungi help it obtain water and minerals like phosphorus, while nitrogen-fixing bacteria help it obtain nitrogen. This means that the roots of prairie-clover do not have to be very extensive, as they mainly serve as attachment points for its associated organisms. Big Bluestem is a warm season grass that flowers in late summer when the soil is relatively dry; this is why its root system is so extensive and deep. In contrast, the June Grass is a cool-season species that flowers in June when the soil is still fairly moist; the shallow, densely hairy roots are able to obtain all the resources the plant needs. Thus, this exhibit nicely illustrates the main strategies that plants use to exploit different niches in the soil both in space and time.

I recently read that, thanks to Covid-19, there’s been a run on Christmas trees because so many people are staying home for the holidays this year. In a world that suffers from plant blindness (i.e. an inability to see the trees for the forest), “Christmas trees”, are among the most well-known “species” of plant. Except that “Christmas tree” is not actually A species; it is ANY kind of coniferous (i.e. cone-bearing), evergreen tree that we decorate. So, if you don’t know much about conifers, here are 10 fun facts about these common trees many of us share our homes with once a year.

Manitoba’s conifers are not like people: they don’t have different genders. Conifers produce both male cones, which produce sperm, and female cones, which produce eggs. The male cones are typically produced on the lower branches and the female cones on the top ones. This positioning helps to prevent self-fertilization because the sperm-containing pollen won’t fall on the trees’ own female cones.

The seeds of most conifers have a thin “wing” attached to them. These wings help the seeds, which are near the top of the tree, glide some distance away, so that the baby trees do not have to grow in the shade of their parent. Juniper (Juniperus spp.) and yew (Taxus spp.) seeds are contained in fleshy cones (incorrectly called “berries”), which are eaten by birds. Thus, they can also fly, although they will be in the stomach of a bird when they do. Fortunately, the seeds are usually not digested, just the fleshy part. They are usually excreted intact in the birds’ dung.

Unless you have a bidet, don’t use any paper products at all, and live in a house made entirely of straw, you have conifers in your house all the time. Paper products like toilet and wall paper, paper towel, newsprint, cardboard and printing paper are all made, at least in part, with “softwood” trees, which are conifers. As well, much of the timber we use to build our houses and furniture comes from conifer trees like pine and spruce. If you eat pesto sauce or drink gin, you are also consuming conifers. Pesto sauce is typically made with pine nuts, and gin is usually flavoured with juniper cones.

Conifers are the oldest seed plants; they evolved about 300 million years ago in the Carboniferous Period. Unlike the earliest land plants, which still needed water to reproduce, conifers did not: their sperm became contained in pollen grains, which could be transported to other plants by the wind instead of water. This enabled conifers to live in relatively dry areas. They became the dominant plants during the “Age of Dinosaurs”: the Triassic, Jurassic and Cretaceous Periods. So, any plant-eating dinosaurs would probably have eaten conifers. Fortunately, dinosaurs are extinct so they will not eat your Christmas tree.

Wanting more conifer trivia? Check out this post from the past to learn why people drank conifer “beer”: click here to read.

Enjoy a tree-filled holiday!