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.

An unpredictable orchid, and other Rondeau stuff

August is the time when one of the rarest orchids in Canada is to be looked for. As it turns out, the only known location for it in the entire country is Rondeau. There are some historic records for it in the southern Essex County area, where it was first discovered in Canada back in about 1950. However that woodlot is small, heavily grazed, and the orchid has not been seen there in over 25 years.

The orchid I refer to is Nodding Pogonia (Triphora trianthophora), and it is a provincially and federally endangered species. While numbers of this orchid have, on occasion, been more than 1000 plants, in recent years the numbers are considerably lower. Unfortunately there has been more than one year recently where flowering was minimal and there was no successful seed production at all.

The other day, I ventured to Rondeau in the morning to check on the orchid. I have been monitoring it via some study plots for over 30 years, and for more than a decade before that, I searched for it regularly with varying degrees of success. One of its peculiarities is that the flower buds of the entire population develop to a certain stage, then on the second morning following a significant night-time drop in temperature, all of the blooms will open up....but just for the one day. It may be several days, or more than a week before the process repeats itself. Timing is everything, and one of the things we don't know is just how much of a temperature drop is required to trigger the buds to open up.

When I arrived at the spot where there were a few plants, I saw this:

The buds were developing nicely but seemed like they had a way to go before being ready to open. So I waited for a couple of days, and this is what I found upon my return:

They had opened the morning before, and were now closing up!

This is what I was hoping to find (photos from previous, more successful times):

But it wasn't to be on this day. Perhaps later in August.........

To get a fuller appreciation of the unusual nature and complexity of this endangered orchid, check out my earlier blog post here.

Even though I was not successful on this trip to capture the Nodding Pogonia in good flower, I did manage to see a few other things. On the walk to the orchid site, I noted these seed pods developing. This is an uncommon woodland milkweed, known as Poke Milkweed (Asclepias exaltata). The seed pods are smoother and considerably slimmer than the more abundant and widespread Common Milkweed (Asclepias syriaca).

There were some flowering grasses along the way. Grasses do have flowers, and they are wind-pollinated. These are the flowers of Big Bluestem (Andropogon gerardii), a typical prairie and savanna species. This photo shows the male parts--the anthers--dangling down, as well as the smaller purplish female flowers sitting tightly to the stem.

 Sometimes the flowers are distinctly yellowish rather than purplish.

On a part of the walk along the Tuliptree Trail, I came across this little critter.

 It is the nymphal stage of a Leaf-footed Bug. It is less than 10 mm in total length, and being an active little critter, was difficult to get in focus all the time.

A much larger invertebrate critter was this meadowhawk, probably a Ruby Meadowhawk, but sometimes the several meadowhawk species found in the area are difficult to tell unless you examine genitalia.

Along the beach dunes, there is a profusion of Cylindrical Blazing-star (Liatris cylindracea) coming nicely into flower. It is not a common species, but restricted to sand prairies and the sandy beach dunes of Rondeau's east beach area are perfect for it.

Maybe on my next trip to Rondeau, I will have had some success in photographing Nodding Pogonia, but if not, there is always lots of other things to focus on!

Tallgrass prairies of Walpole, in their prime

I have been fascinated by prairie and savanna from at least as far back as 1973, when I was working at Rondeau. And since the 1980s, I have had the privilege to be able to explore some of the finest tallgrass prairie and oak savanna in Ontario, and arguably Canada. The prairies of the Walpole Island First Nation are indeed remarkable and spectacular. One of the prairie sites has, on more than one occasion, hosted a breeding pair of Henslow's Sparrows!

You may remember a previous post, in early July, where I was able to visit one of the more remote prairies at Walpole Island, along with the owner and her family. It looked like this:

I had memories of this site from a few years earlier, when it was in its peak of colour with the Dense Blazing-star in its prime, along with several other showy species, so we planned to re-visit in early August to again see it in that showy condition. On the way in, we saw various prairie flowers in their prime, including Flowering Spurge.

Flowering Spurge (Euphorbia corollata)

Grey-headed Coneflower was also doing well. It is provincially ranked as S3, meaning there are fewer than 80 locations for it in Ontario and is vulnerable to extirpation..

Gray-headed Coneflower (Ratibida pinnata)

As we got to the site we were headed for, we were not disappointed.

This image was taken from a very similar vantage point as the first one in this post, but at a slightly different angle.

Dense Blazing-star (Liatris spicata) is one of the prairie plant species which many consider to be iconic.....that is, when one sees it, it evokes a sense of place that is a high quality tallgrass prairie. Mind you it can grow in some rather disturbed sites as well, but in a setting such as the one above with a multitude of other quality prairie species, it truly is an indication of a special place. Dense Blazing-star is a Threatened species under the Endangered Species Act. Under the Provincial Ranking system, it is S3.

Purple is the primary colour, but if you look closely at the image preceding this, you may have noticed a white plant. It is a rare white colour form; less than one per cent of all blazing-star stems are white. It serves to add to the diversity of colour at this time of year when so many prairie plants are purple against a green background.

On the day of our visit, it was a wonderful day to see some butterflies as well. Monarchs, Red-spotted Purples and Black Swallowtails were fairly abundant, but the one that caught my eye was Giant Swallowtail. There were several flitting about, enjoying the nectar of the rich purples available to them in this setting. Giant Swallowtails are ranked as S2 in the provincial ranking system, meaning that there are likely fewer than 20 populations and have a restricted range in Ontario and are very vulnerable to extirpation.

In both of these cases, the swallowtails chose to sip on the flowers of an ironweed rather than the blazing-star and that seemed to be the case most of the time. I'm not sure if the deeper purple colour was more attractive, or maybe the nectar was more satisfying. I'm not a butterfly whisperer to know that detail.

There are two species of ironweed on the Ontario prairies. For many years it was believed there was just one species, but in the early 1990s while a botanical colleague and I were photographing some prairie plants on Walpole, he realized there was something different about some, and after a closer examination of images and confirming using technical manuals, I concurred, thus adding with some certainty that there was in fact another species. The differences are somewhat subtle, and are based in part on the number of florets (small, individual flowers on the flower head). One species is Tall Ironweed and the other is Missouri Ironweed. The next photo is of the latter, and most recently confirmed, species. It is provincially ranked as S3.

Missouri Ironweed (Vernonia missurica)

Of course tallgrass prairies are more than just colourful wildflowers, although they are the showier plants. But as the name 'tallgrass' suggests, grasses are a major component of such a prairie. A healthy prairie in the mid-west consists of about 70% grasses, although there are only a handful of species making up that ~70%. Here in the eastern range of the tallgrass prairie biome, it is believed that wildflowers, collectively called 'forbs', make up about 50% of the vegetation in a healthy prairie, and grasses the other 50%. This may be due in part to the greater amount of precipitation in the east. Prairie grasses in general have deeper root systems than most forb species, so that in the drier part of the prairie range in the mid-west, the grasses have the advantage over the forbs. It may also be partly due to the greater presence of savanna, those prairie-type habitats where up to 25% of the cover is made up of fire resistant trees, usually oak species. Some forbs that do well in an oak savanna will also do well in a tallgrass prairie.

Indian Grass (Sorghastrum nutans) is one of the main grasses to be found on a tallgrass prairie. Grasses have flowers too, although most people do not pay much attention to them. This particular plant was in good flower, with the bright yellow stamens visible here.

In this next photo, there are some tall grasses visible amongst the forbs, although more in the background. They are Big Bluestem (Andropogon gerardii), a.k.a. Turkeyfoot, named because of the 3-4 flower and seed spikes at the top that may resemble the foot of a turkey. It is by far the most abundant grass of most tallgrass prairies.

Also in this image is a Tall Sunflower (Helianthus gigantea) visible in the upper right. In a few days, this scene will have taken on a decidedly yellow look, as the many goldenrod species open up. There are some goldenrods in this image that are in a tight bud stage, but have not yet opened.

I will be posting more on Ontario's tallgrass prairies in the future!