Some Spring-flowering Grasses
Identifying grasses depends first and foremost on what they look like, of course, but other characteristics can provide clues to identity, such as habitat and, to a lesser extent, time of flowering. Most grasses flower from midsummer onwards, raising tall flowering stems aloft to the level of the general vegetation giving their flowers a good chance of wind pollination. Hence when grasses flower early they stand out from the crowd. In this article, I’ll look at four species that flower in May or early June.
Oryzopsis asperifolia, rough-leaved ricegrass, formerly called white-grained mountain rice, is a perennial native grass which grows in relatively dry, open forests. It is easily seen in the Edmonton river valley, flowering from the middle to the end of May while the ground vegetation is still spring-sparse, especially on well-drained escarpments. It is also common on sandy soils in local pine forests, where it is often found with purple oatgrass (Schizachne purpurascens), which I will deal with in a later article. It is a tufted grass with basal, relatively broad (4-9 mm wide), flat, leaves that are rough to the touch, especially below; they are erect when young but later splay out over the ground in a looser tuft. The flowering stems, 25-65 cm tall, bear only reduced leaves with short blades and are topped by a cylindrical, spike-like panicle of greenish spikelets to 13 cm long.
The spikelets are 5-7 mm long with thin, green-veined glumes of about the same length that have translucent sides and tips and contain a single floret. The lemma is hard, whitish and shiny at maturity, sparsely hairy except for the tuft of short white hairs at the base and with a terminal awn 5-10 mm long that soon falls off. The lemma margins overlap, enclosing the similar palea, both in turn enclosing the grain and falling altogether in late spring as a unit that resembles a rice grain, hence the plant’s Latin and common names.
With its broad tufts of leaves which can be bright green or bluish-glaucous, I think this grass makes excellent ground cover, although it does not seem to be widely cultivated. It might do well mixed in with other vegetation such as juniper or common bearberry. Also called winter grass because its leaves remain green during the winter, it supplies a splash of green as soon as the snow melts, followed by the bright new leaves and flowering stalks of the season, another sign of spring.
Rough-leaved ricegrass occurs widely across Canada and the northern U.S.
Meadow foxtail (Alopecurus pratensis) and creeping foxtail (Alopecurus arundinaceus) are both tall perennial grasses, native to Eurasia, that have been widely introduced to the cooler parts of North America for forage and have become increasingly common in Alberta. (See Derek Johnson’s article and local commentary at https://www.anpc.ab.ca/wiki/index.php/Alopecurus_arundinaceus). They both flower from mid May to mid June, and are very similar to one another, having flat, broad leaves (4-8 mm wide in meadow foxtail, up to 12 mm in creeping foxtail) and very narrow, spike-like panicles, 3-10 cm long, produced on flowering stems from 30 cm to over a metre tall, and densely packed with softly hairy spikelets. An obvious difference between the two species is that meadow foxtail is densely clumped, with only short rhizomes and several flowering stems per clump, whereas creeping foxtail produces single stems from long, creeping rhizomes and hence is patch-forming. Both occur in the moist soils of meadows, fields, shores and roadside ditches, with creeping foxtail particularly favouring this last habitat. (Road development has a lot to answer for in promoting the spread of non-native species!)
There are subtle differences between the two species in spikelet morphology, although in both the spikelets contain only one floret consisting of a lemma (without a palea) nestled between two equal-sized glumes. In meadow foxtail, however, the spikelet is elliptic or oblong-ovate in shape and the tips of the glumes are either parallel or point towards each other, whereas in creeping foxtail the spikelets are somewhat urn-shaped with spreading tips. The lemma is as long as the glumes in meadow foxtail and has a 5-10 mm long, bent awn, attached towards the base and extending for 5-10 mm beyond the lemma; in creeping foxtail the lemma is shorter than the glumes and the bent awn is shorter, barely extending beyond the length of the lemma. In both the green keel and lateral nerves of the glumes are long-hairy, giving the panicle its soft feel.
Superficially, the foxtails resemble timothy (Phleum pratense), and are often confused with it. However, the spikelets of timothy, a tufted grass of pastures and a frequent escape into natural communities, lack the soft hairs of the foxtails, and the panicle feels rough to the touch. Another give-away is that when post-mature and before disintegrating, the panicles of the foxtails turn black, and the spikelets fall completely away from their little stalks, whereas the fruiting panicles of timothy are brown and the (single) floret per spikelet falls off while the glumes remain attached to the stalks.
A good place to see creeping foxtail is at the corner of Highway 16 and Atim Road east of Spruce Grove, as one turns to access Wagner Natural Area. Here it has extensively colonized the ditch. Meadow foxtail is a problem at Nisku Prairie where it may have spread into the drier upland prairie from the Gwynne Channel and thrived in wetter seasons. Herbiciding has reduced its numbers somewhat but we have also had some success smothering it with mown hay! Unfortunately, the creation of any bare ground, say, by removing smooth brome, favours its spread. (The catch-22 of invasives!)
I will deal with another locally common but native Alopecurus species, short-awned foxtail (Alopecurus aequalis), when I consider some wetland grasses.
Hairy sweetgrass, northern sweetgrass (Anthoxanthum hirtum, formerly Hierochloe odorata) is a perennial grass, native to both northern Eurasia and the northern parts of North America. It is very popular ethnobotanically because of its coumarin content, which produces a vanilla-like scent that retains its fragrance on drying. It is used in religious ceremonies and for medicine by Indigenous peoples in Canada and is called holy grass in Britain because of the former practice of strewing it in church doorways on holy days.
It produces tufts of bright-green leaves, 2-5 mm wide and characteristically shiny on the underside, from creeping rhizomes. The flowering stems grow 40-80 cm tall and bear two to three sheathing leaves with short blades, characteristic of the plant (and an aid in identifying the grass in vegetative condition). The panicle is 7-15 cm long, open, and with two spreading branches at each node; a single, shining, greenish or purplish and later brownish spikelet is borne at the end of each branch tip. The spikelet, 4-6 mm long, is elliptic to ovate, with pointed tips, and contains three florets only the central one of which is bisexual and fertile, the two lateral, boat-shaped ones producing stamens only. The floret is subtended by a pair of membranous, broadly ovate glumes of more or less equal size and the same length as the spikelet. The staminate lemmas have hairy margins and the lemma of the bisexual floret has a hairy tip; the latter is slightly smaller than the staminate lemmas at 3-3.5 mm long.
Hairy sweetgrass grows in the moist soils of fields, roadsides, verges, and sandy areas; being rhizomatous it can often form extensive patches. It flowers in May although its panicles often persist in a dry condition throughout the summer. In popular demand, it can be propagated by its rhizomes, but growing it from seed has proved difficult because viable seed is scarce. In part this may be because collecting isn’t undertaken early enough: the fertile floret falls away, leaving the glumes and staminate florets behind, giving the impression of an intact panicle. Or the florets may become infected with insects, or, there may be other reasons… The literature suggests that lack of viable seed is common. If anyone knows of a population producing good seed, please let us know…!
References
Flora North America, online. Vol. 24. Oryzopsis asperifolia, page 168. Alopecurus pratensis & A. arundinaceus, page 782. Anthoxanthum nitens, page. 764.
Johnson, J. Derek. 2012.07.12. Alopecurus arundinaceus. https://www.anpc.ab.ca/wiki/index.php/Alopecurus_arundinaceus
Kershaw, Linda and Lorna Allen. 2020. Vascular Flora of Alberta: An Illustrated Guide. Self-published. Kindle Direct Publishing. Poaceae.
Moss. E. H. 1983. Flora of Alberta. 2d ed. rev. by J.G. Packer. Toronto, University of Toronto Press.
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