Field Botanists visit Bickford Oak Woods

Last Saturday I had the privilege of meeting a group of about 20 enthusiastic members of the Field Botanists of Ontario at the Bickford Oak Woods Conservation Reserve in west central Lambton County. The outing was planned several months in advance, and the main target species from a botanical standpoint was to see the one and only place in Canada where Swamp Cottonwood (Populus heterophylla) occurs. It was first discovered by the trio of Gerry Waldron, John Ambrose and Lindsay Rodger back in 2002 while they were doing a vegetative inventory in the early stages of this site becoming a Conservation Reserve. It isn't an easy species to find, even when you know where it occurs at this site. One has to access the spot through a planted prairie, then along the woods for several hundred metres, and eventually following an overgrown logging trail for several hundred more metres. It is then necessary to strike off through the woods, cross a muddy creek and then venture another couple of hundred metres to find the buttonbush swamp which has a number of stems of this rare tree. The FBO members were eager, so off we went.

On the way to the spot where the cottonwood grows, we came across a number of interesting species. This first one, Whorled Milkweed (Asclepias verticillata) was a new one for some of the members.

 The wet spots along the trail, of which there were many, had a few stems of this Square-stemmed Monkey Flower (Mimulus ringens).

We came across a Giant Swallowtail butterfly. In this area, one of the main plants that the larvae of the Giant Swallowtail survives on is Prickly Ash (Xanthoxylum americanum). As one might guess by its name, it is a thorny species, and not one that is fun to hike through. Seeing this beautiful large butterfly was a bit of compensation for the time spent shortly after trying to get through the Prickly Ash thickets without getting too scratched up.

 At one point along the creek and floodplain area there were some of these Cardinal Flower (Lobelia cardinalis) in fine shape. It isn't a rare species by any means, and in fact is quite widespread across southern Ontario and beyond, but the brilliant scarlet colour of the flowers is always a treat to come upon.

 Most oaks at this conservation reserve have been logged at one time or another. There are very few large examples remaining. However this White Oak (Quercus alba) is relatively large. Probably because it is growing right along the edge, and has lots of large lower branches, it was less valuable from a timber standpoint at the time the site was logged half a century or more ago.

As mentioned, the intended target species for this hike was the Swamp Cottonwood. This next image shows what the site looks like in the spring, with lots of variable sized trunks of this rare species growing in standing water.

 And this is the characteristic leaf: it is large for a cottonwood, has a heart-shaped base, and the leaf stem is round, not flattened as most Populus species are.

This is the happy group of FBO members, in front of a cluster of Swamp Cottonwood tree trunks.

After achieving our target of seeing the Swamp Cottonwood, we returned to the parking lot and had some refreshments. With about 4 hectares of planted prairie adjacent to the parking lot, we took a bit of time to explore the species present. Big Bluestem, a.k.a. Turkeyfoot (Andropogon gerardii) is the most common grass in most tallgrass prairies.

Gray-headed Coneflower (Ratibida pinnata) is often quite abundant.

 False Sunflower(Heliopsis helianthoides) is one of the many sunflower types found in a prairie.

 Dense, or Spiked, Blazing-star (Liatris spicata) is probably one of the best known, iconic prairie wildflowers. It is a Threatened species in Ontario.

 Compass Plant (Silphium laciniatum) is not common at all, but really stands out on a prairie.

 Another Silphium species is Cup-plant (Silphium perfoliatum). The close-up of the paired leaves show the cup-like aspect which gives it its name.

 Prairie Dock (Silphium terebinthinaceum) is another iconic tallgrass prairie species. The shovel-shaped leaves are clustered at the bottom of a tall, quite rigid stem that sometimes grows more than 3 metres high.

 Tall Coreopsis (Coreopsis tripteris) is another rare prairie plant restricted to the tallgrass prairies of extreme southwestern Ontario.

 Yet another member of the sunflower family that is common on the prairie is Tall Sunflower (Helianthus giganteus). It too often grows 3-4 metres high or even higher.

It was an excellent day, and with great weather right up until the end of the outing. Just as the last of us were packing up the vehicles, it started to sprinkle and there was the occasional rumble of thunder in the background. Before we got too far down the road, the rain came down in torrents.

August Tallgrass Prairie really is august

Tallgrass prairie is one of my favourite habitats to explore and photograph. A great prairie often looks like this in the late winter or early spring, depending on the overall condition of it in the first place.

 In just a few weeks after a spring burn, it will look lush and green, with splotches of colour here and there such as what the Butterfly Milkweed contributes in the next image.

But by August, tallgrass prairie really is 'august', as in majestic. Very quickly a kaleidoscope of colours appear: purple, pink, white, yellow and blue, in no particular order.

There are a few august prairies in southwestern Ontario to enjoy. The two I know best are Ojibway Prairie Provincial Nature Reserve in south Windsor, and even larger and more extensive prairies at Walpole Island First Nation (WIFN). The prairies around Ojibway are open to all for exploration and the city-owned nature centre across the road is definitely a must to visit. The prairies at Walpole are not open, however. Most occur on private property, are well away from the road, and permission must be obtained. I always go with someone from WIFN and even then, only when permission has been granted.

This next image was taken on a recent visit, and looking in the same direction as the previous image, albeit a little closer to the lone tree on the right. The purples of Dense Blazing-star stand out tall amidst the gradually increasing yellow of various species of goldenrods.

 Where you find Dense Blazing-star (Liatris spicata), you often also find Rough Blazing-star (Liatris aspera), a little smaller and with its flower head not as densely packed with flowers. Dense Blazing-star is listed as Threatened on the respective provincial and federal legislation dealing with Species At Risk (SAR).

Dense Blazing-star

Dense Blazing-star

Rough Blazing-star is not legally listed, but at S2 in Ontario, is Imperilled with between 6-20 locations known.

Rough Blazing-star

Sometimes you come across a blazing-star that is white. It doesn't show up really well in the next image, as it is in the centre background under multiple stems of Prairie Dock (Silphium terebinthinaceum), but a close-up of a white Dense-Blazing-star follows.

Prairie Dock is not listed on any SAR legislation, but is S2 (Imperilled). Its large very rough sandpapery leaves which look like a shovel, and tall single flowering stem are characteristic. Note: if you are out on a prairie and need toilet paper, do not be tempted to use the leaves of Prairie Dock!

Another showy purple plant is Missouri Ironweed (Vernonia missurica). It is very similar to Tall Ironweed (V. altissima) with the main differences being the number of florets in each flower head.

Missouri Ironweed

Sticking with the purple theme, but much, much smaller, is Pink Milkwort (Polygala incarnata). It is legally Endangered in both federal and provincial legislation. In Canada, this annual plant occurs only at Walpole and Ojibway Prairie.

While you are down on your hands and knees examining Pink Milkwort, you just might stumble across a very rare orchid: Southern Slender Ladies'-tresses (Spiranthes lacera var. gracilis). It isn't restricted to tallgrass prairie. It is only known from a handful of locations in Ontario, and while it isn't yet on a legislated list of SAR, it is S1, meaning Critically Imperilled since there are no more than 5 locations known for the province. I came across three individuals recently at Walpole Island.

It is small....the third image is several times life size. If you find it, the dark green centres of the individual flowers will separate it from other members of the Spiranthes genus.

Another prairie plant with a dense cluster of white flowers is more common, and more visible since it is much taller: Culver's-root (Veronicastrum virginicum). A fully mature plant will have multiple flowering spikes, somewhat resembling a candelabra, while a younger plant will only have a single flowering spike.

Another plant with white flowers at this time of year is Grass-of-parnassus (Parnassia glauca). The fine green lines on each petal are noteworthy.

There are numerous species of aster and goldenrod just beginning to display themselves on a good quality prairie. Canada Goldenrod is often the most obvious of the goldenrods, but several rarer species are beginning to appear, including Riddell's Goldenrod (Solidago riddellii). It is easily identified by its long, linear downward-curving leaves which in cross-section are V-shaped. Its flower head is slightly rounded. This next photo is of a plant that is almost, but not quite, out in flower.

Riddell's Goldenrod

I plan to show other goldenrods, asters and rare later season tallgrass prairie specialties in a future post.