Lichens and Galls and Brackets, Oh My!

Once you have documented your tree observation, take a second look to find some of the other organisms that live on or in the tree. Many are as stationary as the trees themselves and give you lots of time to observe and document them.

Some lichens specialize in growing on tree bark. These are the greyish or orange crusty things you will see if you look closely at the bark. As I write this, our community is not yet able to identify many lichens from photographs. Observing and documenting now will help change that. I suspect that just as in most other groups of living organisms, there are common easily recognized species, others that are so similar that they will remain at genus level or get a 'complex' designation, and a few that are only found infrequently. The Manitoba Conservation Data Centre lists 618 different species from found in Manitoba from the barren grounds to the 49th parallel. That's only a third more than the number of bird species found here. :) I think we can make a dent in the unknowns with more data. You will need to get up close and personal with the lichens to help build the library of images needed to make this happen.

Galls often blend in well with the normal growth of the plant so a closer look may be needed to find them. They are a sort of joint project of an arthropod (a mite or wasp usually) and a plant. The arthropod would like to live in the plant and be protected and fed by it - the plant would rather not that happen. Evolution has armed the arthropod with chemical triggers that force the cells of the plant to grow to make the shelter and food it needs. These chemical triggers differ from plant to plant so gall makers specialize in a single species or genus of plants. If you are sure what plant produced the galls, you are more than halfway to identifying the tiny creature that made it. The shapes and colours of the galls that are formed are individual to the gall maker. When you are sure you have a gall observation, let the community working to identify Galls in North America know about it by adding it to this project. Unlike the CNC project which collects observations automatically, the Gall project depends on you to manually add your observations to the project. This strategy works really well for situations where the project is focused on a very specific subset of observations that cannot be found using the base observation data of place and date.

Brackets are the fruiting bodies of fungi living inside the tree. Brackets may be woody, adding a new fruiting layer each year to the previous growth. The lower surfaces of some have gills like the familiar field mushroom that we eat; others have pores or teeth to dispense their spores. Images of both upper and lower surfaces are often needed to help with identification. Some brackets are specialists, and are only found on one tree species, while others are less discriminating, happy to make a home in any one of a number of tree species. I find that the easiest one to identify in our region is the aspen bracket - Phellinus tremulae. It only grows on Trembling aspen - not on any other species in our area. It has a very flat spore producing surface that faces out from the tree at an angle. This surface changes colour with the seasons. Look for this bracket on large mature trembling aspen - once you find one yourself, you will wonder how you missed them before.

More Resources...
Manitoba Conservation Data Centre
Wild Species 2015: The General Status of Species in Canada: Lichens
Common insect and mite galls of the Canadian prairies
Mushroom Expert: Phellinus tremulae

Publicado por marykrieger marykrieger, 21 de diciembre de 2020


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