Northern Ontario Plant Database

Plant Description

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Brachyelytrum aristosum (Michx.) P.Beauv. ex Trel.

En: northern shorthusk
Fr: brachyélytrum du Nord, brachyélytrum septentrional

Poaceae (Grass Family)

Poaceae Reproductive Structures: A unique floral terminology is associated with grasses, since grass flowers are so different from the image that most people have of a typical flower, with large, colourful petals. Grass flowers are called florets and are arranged in a simple inflorescence, called a spikelet, which is subtended by 2 bracts, called glumes. Spikelets, in turn, are arranged in secondary inflorescences, usually racemes or panicles. Each spikelet is composed of 1 or more floret. Each floret is composed of 2 bracts – an inner bract, the palea, which is situated closest to the ovary, and an outer bract, the lemma, which is usually larger and firmer, and partially surrounds the palea. The tip of the lemma often extends into a long bristle, called an awn. The back surface of the lemma may be smooth or marked by prominent veins called nerves, which are often useful in identification. Enclosed within the lemma and palea of a typical floret is a single, superior ovary, bearing 2–3 feathery stigmas, 3–6 stamens, and 2–3 reduced floral parts, called lodicules, which are sometimes modified into tufts of bristles or hairs of various length. In spikelets with more than one flower, the florets are arranged along a central axis called a rachilla, When florets mature, the rachilla often breaks into short segments and dehisces with the floret. These terms are used throughout the descriptions of grass species.

General: A perennial grass, spreading by rhizomes; easily recognized by its narrow panicle and few, long-awned spikelets. Stems are slender, erect, to 1 m tall.

Leaves: Blades are linear-lanceolate, flat, to 15 cm long and 0.8–1.6 cm wide, with a tapering, pointed (acuminate) apex and entire margins . Leaf sheaths and blade surfaces bear short hairs, which give the leaves a rough (scabrous) texture. The ligule, a thin, translucent flap of tissue, 1–2 mm long, is situated at the junction of the leaf sheath and blade.

Inflorescence: A slender nodding panicle, to 15 cm long, bearing few spikelets.

Spikelets: 1-flowered, about 1 cm long, excluding the long awn. Lemmas 0.8–1.0 cm long, with 5 weak veins (nerves), smooth or bearing fine hairs (less than 0.2 mm long) towards the tip and on the nerves. Lemmas end in a long, scabrous awn, 1.2 – 2.5 cm in long. The smaller, thinner palea is closely surrounded by the lemma. The spikelets dehisce above the glumes when the grain (caryopsis) is ripe, leaving behind the small, persistent glumes. Attached to each dehisced spikelet is a bristle-like segment of the rachilla, which is about the same length as the lemma.

Habitat and Range: Moist, rocky or sandy hardwood and mixedwood forest stands in southern boreal regions of Ontario. The northern shorthusk can also be found in wet organic soils of hardwood swamps, but is not found in areas overlying limestone bedrock.

Similar Species: The bearded shorthusk, Brachyelytrum erectum, is a temperate species that occurs in southern Ontario and the eastern United States. The northern shorthusk, Brachyelytrum aristosum, was once considered to be a variety of the bearded shorthusk. A comparison of the traits of these two species is provided in the table below. See also the Brachyelytrum erectum webpage, from The Noble Foundation Plant Image Gallery.

	Brachyelytrum aristosum (northern shorthusk)	Brachyelytrum erectum (bearded shorthusk)
nerves on lemma	weakly nerved lemma	conspicuous nerved lemma
hairs on lemma	glabrous or with fine hairs, less than 0.2 mm long	scabrous throughout with short hairs, 0.2–0.5 mm long
length of lemma	lemma 8.5–10 mm long	lemma 11.5–13 mm long

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