12 days, Sanford 14PA10 and Poison Ivy

Sanford 14PA10 is located in the RM of Macdonald. The La Salle River flows from the west to east through the square by the town of Sanford. The square is divided by mile road grids and drainage ditches. Agriculture dominates the land use in this square.

At the time of posting, 23 observations had been uploaded by 6 observers, led by @rjr-mb . 18 species are represented including 5 plants and 5 birds. The survey for the Breeding Bird Atlas of Manitoba confirmed 32 bird species nesting here, with another 37 species probable or possible. Here's the full list.

There are a few species that I feel everyone in Manitoba should be able to identify confidently if they are going outside their own door. For these species, your identification expertise will not only give you higher identification numbers but also make your experience outdoors more pleasant.

Today we are going to brush up on our Poison Ivy identification skills. The species found in Manitoba is Western Poison Ivy (Toxicodendron rydbergii). Some of your reference books may use the name Rhus radicans var rydbergii instead but it is the same plant.

Scoggan's "Flora of Manitoba" informs us that the plant was first collected in Manitoba by Bourgeau in 1857. Eugene Bourgeau was the member of the Palliser Expedition assigned to collect plant specimens for the herbarium at the royal gardens at Kew . Irene M. Spry describes in her book "The Palliser Expedition" their first experience with the plant near Rainy River...

Here they encountered poison ivy for the first time, a plant that, they were surprised to find, produces a most intense itching sensation attended with considerable swelling and rash. These effects lasted for many days; some of the voyageurs suffered severely from them.

While the effect on skin is an excellent fieldmark, I don't want any of you or your companions to suffer so lets make sure to notice it before we get too close.

Scoggan describes the plant's preferred habitat as "woods, thickets, sandhills and clearings in the southern two-fifths of the province". In my experience, it is most frequently found in or at the edges of treed areas where the trees are further apart and there is little or no shrub layer to block the sun completely. The plant needs sun but can tolerate a bit of shade. It cannot grow in very wet conditions. It also does not like very acid soil conditions - so not likely to be found in a peat bog. If the soil is sandy then it is even more likely that you will encounter the plant. The plants preference for drier sunny edges and clearings means that it will be frequently found right at the trail edge.

Finding a single plant is very unusual. Poison ivy generally grows in patches or colonies. Each plant is separated a little from its neighbour, just enough so that the individual plant's leaf canopy gets its own patch of sunlight. It has woody stems but never gets very tall, more ankle height than knees on grown-ups. Wearing something on your legs and feet is generally recommended in areas where the plant is abundant.

"Leaves of three, let it be" is a good start to learning this plant in the summer. Leaves of three leaflets grow from a single stem. Each leaflet has an irregular toothed margin. Usually the number of 'teeth' on one side of the leaflet is not the same as on the other side - and counting those teeth shouldn't strain your brain. Lots and lots of small teeth indicate that you are not looking at a poison ivy plant. In the fall, winter and early spring, the most obvious field mark are the tight clusters of yellowish ridged berries.

There are a few other plants that get confused with this one - the ones that people have asked me most about over the years are Wild Sarsaparilla (Aralia nudicaulis) and the two Parthenocissus - Thicket Creeper and Virginia Creeper. Wild Sarsaparilla does not have a woody stem, its leaves are in groups of 5 finely toothed leaflets, and it has round clusters of dark blue berries with no ridges. The two creepers are woody but they are vines. The creepers also have 5 or more leaflets with many teeth and clusters of very dark colored berries.

Happy Saturday and stay out of the poison ivy!

Posted on April 17, 2021 03:56 PM by marykrieger marykrieger

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