Rubus of the North Shore

For a little over a year lichens have been a predominant focus while I’m out exploring. This is largely based on the landscape. That’s just the thing to do on the North Shore. Between cliffs and talus, rivers, cedar/black ash swamps, shore line, pine forests, maple forests, etc. there is a tremendous amount of high quality habitat home to a great diversity of species. While there certainly are some fascinating species in the cities and surrounding area, it just isn’t the same. 

So if not lichens what next? The brambles (blackberries and raspberries) in the genus Rubus are the top candidate for a new focus for now. Just as the North Shore is the place to lichenize, the Anoka Sandplain is  the place to brambulate? Rubus has 33 species and 2 hybrids native in Minnesota, by far the most diverse woody plant genus. Compare that to the willows which only has about 18 species and a handful of nonnative species (they readily hybridize so who could say how many of those are sitting around). It is quite the complex genus. There are 5 subgenera: the dwarf raspberries, the cloudberries, the thimbleberries, the raspberries, and the blackberries. The blackberries are the most species-rich and are further divided into the highbush blackberries (sections Alleghenienses, Canadenses, and Arguti) , the dewberries (section flagellates), and the bristleberries (sections Setosi and Hispidi). The taxonomy of this genus is widely disputed, for example, some authorities list most of the bristleberries under one highly variable species - R. flagellaris. Minnesota does not recognize that species as present in the state, but there are 12 species of

bristleberries, many of which some would consider synonymous with it. So there’s already a lot of ambiguity there. Adding to that, to positively identify most species you need both primocanes (first year solely vegetative growth) and floricanes (second year flowering/fruiting growth). each year plants put out new growth so these should often be present. Winter dieback, shade grown, or young plants might mean that only one type of cane is present and you’d have to revisit next year. All of the known blackberries (27 species) in the state are present in the Sandplains except for one. If your looking for brambles the cities are the ideal place. 

I’ve been exploring the brambles in the cities, but the North Shore was calling my name. Why not see what brambles are there? After all finding two uncommon species up there started my interest in the genus. 

There are a handful of common species up there including red raspberry, thimbleberry, and dwarf raspberry. While black-capped raspberry is common out west where I grew up. I’ve enjoyed eating their berries for years. They also have some interesting gall species on them. But the plants themselves have never much interested me as a naturalist. 

I noticed my first native blackberry while hiking at George Crosby Manitou in Sept. of 2024. Well it wasn’t much of a hike they were growing right at the parking lot. Something about the palmately compound leaves of blackberries is just far more aesthetically pleasing than the pinnately compound or simple leaves of the other types of Rubus. The slender arching canes are also just wonderful. I can’t explain why but I think blackberries are the most aesthetic plant. I knew nothing about their diversity or how to identify them at the time. Luckily, Lynden Gerdes did all the work and there is a herbarium collection of Rubus superioris from 2008 at this exact spot. What a cool name! 

Lake Superior blackberry (Rubus superioris)

While rivers and lichens distracted me throughout the fall and winter, a hike to George Crosby with Marcus reminded me of them in the spring. Half-heartedly looking for blackberries, I didn’t see any until later in the summer. 

Reading through Trees and Shrubs of Minnesota, I decided Rubus acridens was the coolest of the bunch. It is currently only known from Minnesota, where it is uncommon and is the only blackberry not found in the sandplain. It occurs only within the Laurentian Mixed Forest, where it seems to grow in early successional forests at edge habitats. Overall very little is known about this species. Being in section Canadenses it also has far fewer prickles than most other species. There was an herbarium record only about 35 miles from Wolf Ridge that I went and checked out right before moving to the cities. 

Sharp toothed blackberry (Rubus acridens)

I was hooked and moving to the cites began exploring and found a fair amount of species. Which brings us back to today. Being in Duluth for a few days I went to all my old blackberry patches I used to pick that I found over the years in college. That was back when they were all just blackberries. 

The most accessible patch is around the parking lot and power lines of Enger Tower. Keying them out they appear to be Rubus acridens. Distinguishing traits include: few prickles found on pedicles, petioles, and canes; pedicles, petioles, and canes lacking gland-tipped hairs; lower surface of leaf mostly lacking hairs; and inflorescence a leafy corymb with 2-8 flowers. 

Sharp toothed blackberry (Rubus acridens)

Then came the blackberries at Tischer. They keyed out to Rubus canadensis. Being in section Canadenses with Rubus acridens they looked very similar. Differences include far less prickles and inflorescence a raceme with 4-16 flowers. 

Smooth blackberry (Rubus canadensis)

The blackberries at the gravel pit of the Island Lake ski trails all seemed to key out to Rubus superioris. Important traits include: canes with needle-shaped prickles only, no broad-based prickles; canes and petioles lacking gland-tipped hairs; lower surface of leaves smooth to the touch; inflorescence a raceme; and hairs on pedicles being gland-tipped. 

Lake Superior blackberry (Rubus superioris)

At Chambers Grove I saw Rubus allegheniensis having broad-based prickles; hairs on pedicles, petioles, and primocands being gland-tipped; velvety lower surface of leaf, and inflorescence being a raceme twice as long as wide. Also present was Rubus ablatus: broad-based prickles; pedicles lacking gland-tipped hairs; lower surface of leaves velvety; central leaflets of primocane elliptical, and inflorescence a short raceme. 

Allegheny blackberry (Rubus allegheniensis)

Plains blackberry (Rubus ablatus)

Without keying these out they all look more or less identical from these pictures. I’m also very new to the genus and could easily have misidentified some of them. It makes sense the debate of what makes a species distinct from another. The genus seems pretty well surveyed in certain parts of the state, but the Duluth area does not seem like one of them. What else is hiding out there? Where?

Subgenus Rubus, the blackberries, all have unique habitat preferences. A common them is edge habitats in early successional forests dominated by poplars or pines. This means along trails are a great spot to look for them, providing a little more light and release from competition. In Duluth this habitat is also a favorite of tansy, buckthorn, and mullein. All of which are invasive species. Ma y of the patches were being overrun by these, how much longer will they persist? Another plant that likes somewhat similar habitat which I saw at two of these locations is Canada buffaloberry. 

Canada buffaloberry (Shepherdia canadensis)

I began talking about lichens so I’ll close with some I’ve found down by the cities. I spent the 4th of July at Taylor’s Falls and found salted shell lichen a far better experience than watching some fireworks. A few days later at Shadow Falls I found some interesting lichens in the family Collemataceae, John thinks maybe Enchylium tenax or bachmanianum. The most surprising find was broken yolks. Which was posted on iNat a few months ago from a cemetery about 4 miles from where I’m currently living. Presumably this is a state record. What a weird place for it to occur. I had to check it out. It was growing on a grave marker of dolomite(?) or something similar. It probably is growing on a cliff somewhere not ungodly far away. 

Salted shell lichen (Coccocarpia palmica)

State Threatened Species

Collemataceae sp. 

Broken yolks (Calogaya decipiens)