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Grasses of Peatlands and Calcareous Habitats (Part 8)

by Patsy Cotterill. All photos by author. WF News, Sep 2022


Slim-stemmed reedgrass, Calamagrostis stricta

L. Calamagrostis stricta. In flower alongside a marl pond in Wagner Natural Area, 2022.07.21.
L. Calamagrostis stricta. In flower alongside a marl pond in Wagner Natural Area, 2022.07.21.

We have already encountered the reedgrass genus, Calamagrostis, in our discussion of the ubiquitous bluejoint, or marsh reedgrass, of wetlands: tall, perennial grasses wi


th rather narrow panicles of numerous, congested, one-flowered spikelets. The florets have a ring of white hairs at the base and a slender awn is attached to the back of the lemma, usually below the middle. The reedgrasses are not an easy group of species to identify, and slim-stemmed reedgrass could be confused with bluejoint with which it may sometimes co-occur in moist meadows and open woodlands. However, it has a more compact, upright and stiff panicle (strict, in a word), with shorter panicle branches than bluejoint, whose panicle is wider, more open and, because the florets are on average slightly smaller, more feathery-looking. At least after flowering, many of our bluejoint populations have panicles that are turned to one side and brownish, whereas in C. stricta the panicle remains erect and compact and becomes straw-coloured on drying.

Calamagrostis stricta. Close-up of the panicle of the same population.
Calamagrostis stricta. Close-up of the panicle of the same population.


Although C. stricta has rhizomes and so can exist in loose patches, it never forms bluejoint’s extensive colonies, nor does it reach the same stature. I tend to associate slim-stemmed reedgrass with peatlands or areas influenced by calcareous groundwater because there are good populations of it in Wagner Natural Area, especially on the shores of the marl ponds. It also occurs in the more organic wetlands at Bunchberry Meadows. Generally, it is widely distributed throughout the province and across Canada.


Close examination of the spikelets will reveal more differences between the two species, such as C. stricta having shorter floret hairs than C. canadensis, and of unequal length. Nevertheless, with a bit of experience the two species can be distinguished by the naked eye, and often when in flower C. stricta is eye-catching because of its beauty.


R. Calamagrostis canadensis. Seen along the Marl Pond Trail in Wagner Natural Area, showing a population of bluejoint, with its feathery, one-sided panicles, in contrast to those of C. stricta. 2022.08.21.
R. Calamagrostis canadensis. Seen along the Marl Pond Trail in Wagner Natural Area, showing a population of bluejoint, with its feathery, one-sided panicles, in contrast to those of C. stricta. 2022.08.21.

A complication for full identification of slim-stemmed reedgrass is that two very similar varieties (formerly considered two separate species) are recognized: the typical variety, var. stricta, and a rather more robust form, var. inexpansa, northern reedgrass. The former is the smaller grass, with spikelets 2-2.5 mm long, and panicle branches 1.4-4 cm long, whereas var. inexpansa’s spikelets are 3-4 mm and panicle branches generally longer (resulting in a broader panicle that is sometimes lobed). The stems of the latter are rough to the touch, while those of var. stricta are smooth.






Although the above taxa are all plants of wet habitats, dry land species of Calamagrostis also occur, for example, plains reedgrass, C. montanensis, at Gibbons Badland Prairie. So, don’t be surprised if, in your travels, you come across reedgrass species in prairie or sandy grassland or on dry mountain slopes.



Muhlenbergia glomerata. Plant growing on an old ant mound in a fen in Wagner Natural Area, 2022.08.21. It is the latest of the peatland species to flower, usually flowering about mid August. The old spikes remain throughout the winter.
Muhlenbergia glomerata. Plant growing on an old ant mound in a fen in Wagner Natural Area, 2022.08.21. It is the latest of the peatland species to flower, usually flowering about mid August. The old spikes remain throughout the winter.

Spike muhly, bog muhly, Muhlenbergia glomerata My experience of the muhly grasses (genus Muhlenbergia) in Alberta has left me intrigued, in that they can’t seem to make up their minds whether they like wet or dry soils. There are six species in the province, Margaret Krichbaum having found foxtail muhly, Muhlenbergia andina, in the sandy soils of a Gull Lake shore near Aspen Beach Provincial Park a couple of years ago. Apart from the rare (not-in-our-area) M. asperifolia, the muhly grasses seem to fall into two groups, those that have a spike-like inflorescence (M. glomerata, M. racemosa and M. andina) and those that don’t (M. cuspidata, M. richardsonis). My first acquaintance with bog muhly occurred in the fens of Wagner Natural Area, hence my belief for several years that it was predominantly if not exclusively a peatland species. (It also occurs adjacent to a peaty wetland along the tamarack trail in Bunchberry Meadows.) It grows on large mounds that appear to have been old ant mounds: Derek Johnson calls it an “ant hill indicator” species. Its roots and short, white-scaly rhizomes are thus well elevated above the water of the fens. (But if you want your feet dry, why choose a fen to live in?)



Muhlenbergia glomerata. Close up of part of the spike showing long awns on the glumes.
Muhlenbergia glomerata. Close up of part of the spike showing long awns on the glumes.

Later, I came across “bog” muhly in moist grasslands, such as at Nisku Prairie and in Elk Island, where, instead of being confined to a mound and tussocky-looking, it forms small green patches. Only the similarity of the flower spikes would clue you in that it was the same species. The stems of spike or bog muhly reach 30-120 cm tall and bear flat green or bluish-green leaves that are 2 mm wide or more. The inflorescences is a narrow, dense, slightly lobed spike 0.5-1 cm wide, in which the shortly stalked branches are appressed to the stem. The one-flowered spikelets are on very short stalks and about 5 mm long, the same length as the glumes which bear awns to 5 mm long, giving the spike a spikey appearance. The lemmas are much shorter at about 3 mm in length and both lemma and palea have long white hairs towards the base. The species occurs widely across North America except for the southern U.S. Edmontonians should be aware of bog muhly’s close relative, marsh muhly (a complete misnomer!) alias green muhly, Muhlenbergia racemosa, which is not infrequently found on the dry escarpments of the North Saskatchewan River valley although it is otherwise quite rare in Alberta. Apart from the difference in habitat a quick field character to check has to do with the exposed stems between the leaf sheaths. Those of M. glomerata are minutely hairy (detectable as a slight roughness), whereas those of M. racemosa are shiny, smooth and often reddish. Perhaps this species pair likes to have dry feet, but live near water, something that could also be said of many humans!



Glyceria striata. Flowering populations along the edge of the Marl Pond Trail, Wagner Natural Area, 2202.07.21.
Glyceria striata. Flowering populations along the edge of the Marl Pond Trail, Wagner Natural Area, 2202.07.21.

Fowl mannagrass, Glyceria striata The mannagrasses, genus Glyceria, of which there are five species in Alberta, are mostly perennial, rhizomatous grasses which all grow in moist situations, fens, wet meadows and stream sides. Other characteristics are that their leaf sheaths are closed for three-quarters of their length, and their lemmas, which are oval and flattened or cylindrical and round, have nerves which run parallel to each other for most of their length rather than converging towards the tip. Local readers are mostly likely to be familiar with the two common species that are emergents, tall colonial plants that form bands around wetland shores. Tall mannagrass,



Glyceria striata. Dense patch showing bead-like inflorescences of green spikelets, in flower, 2022.07.21.
Glyceria striata. Dense patch showing bead-like inflorescences of green spikelets, in flower, 2022.07.21.

Glyceria grandis, of lakeshores, with its large, spreading purple panicles, is likely to be the most seen. However, visitors to Wagner Natural Area are likely to have noticed fowl mannagrass, Glyceria striata, for in certain parts of the Marl Pond Trail, especially in the wooded, hummock-and-hollow sections, it has by late summer formed a conspicuous green verdure along the trail, topped by flowering stems to 80 cm tall. The flat green leaf blades are 2-6 cm wide, and the flower heads are open, spreading or drooping panicles on which the 15-50 small spikelets are strung out, almost like beads on a necklace. These oval, somewhat flattened spikelets consist of 3-6 fertile florets and a terminal sterile floret, subtended by tiny ovate glumes 0.5-1.5 mm long. The lemmas are green or purplish, broadly ovate, rounded on the back and prominently 7- nerved, with whitish-papery tips and edges. The spikelets turn brownish when the grains are ripening. Fowl mannagrass is not confined to peatlands, but does seem to prefer organic soils well supplied with moisture and shade. It is widely distributed across North America except for far north-eastern Canada. Its closest look-alike, the somewhat larger tufted tall mannagrass, G. elata, is rare and confined to southern Alberta and BC.


Glyceria striata. Image from Minnesota Wildflowers (online), showing structure of floret with parallel-veined lemma, palea and grain.
Glyceria striata. Image from Minnesota Wildflowers (online), showing structure of floret with parallel-veined lemma, palea and grain.


References

  • Caadensys Vascan (online)

  • Flora of North America. Calamagrostis key, C. stricta. Vol. 24, pp. 706, 729.

  • Flora of North America. Muhlenbergia key, M. glomerata, M. racemosa. Vol. 25, pp. 145,154,153.

  • Flora of North America. Glyceria, C. striata. Vol. 24, pp .68, 77.

  • Kershaw, Linda and Lorna Allen. 2020. Vascular Flora of Alberta. An Illustrated Guide. Self-published. Kindle Direct Publishing.

  • Moss, E. H. 1983. Flora of Alberta. 2d ed. edited by J.G. Packer. Toronto, University of Toronto Press.

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