Flower:

Usually a loose, open branching cluster, taller than wide, 4 to 12 inches tall, oblong to pyramidal in outline with spreading to drooping branches. Branches are sometimes more compact and ascending to erect with the cluster nodding to one side. Spikelets (flower clusters) are single at the tips of slender branchlets, greenish to silvery to tawny to purple-tinged, 2 to 6 mm (to ¼ inch) long with 2 florets.

At the base of a spikelet is a pair of bracts (glumes) that are both lance-elliptic with a pointed tip, 1 or 3-veined, the upper glume 4 to 6 mm long and about as long as the spikelet or nearly so, the lower glume slightly shorter than the upper glume. Surrounding a floret are a pair of bracts (lemma and palea), both membranous, hairless and jagged along the tip, the lemma 2 to 5.4 mm long and weakly 5-veined with a straight to slightly bent awn that arises from below the middle of the lemma and barely extends above the floret, if at all; the palea is slightly shorter than the lemma and 2-veined. The thickened base around the floret (callus) and the stalk between the florets (rachilla) are both covered in long, white hairs; the rachilla extends to about half the length of the upper floret.

Leaves and stems:

Leaves are mostly basal with a few on the lower stem, stiff, erect to ascending, flat or rolled in along the edges (involute), up to 12 inches long, 1 to 4 mm (to 1/6 inch) wide, ribbed on the upper surface, hairless but rough-textured. Old dead leaves typically persist to the next season.

Sheaths are smooth to slightly rough. The ligule (membrane where the leaf joins the sheath) is up to 8 mm long, pointed to ragged along the tip edge. Nodes are smooth. Stems are mostly rough, multiple from the base, erect to ascending. Plants form dense clumps of mixed flowering and vegetative shoots.

Fruit:

Spikelets turn pale tan as they dry, the mature florets falling away individually, leaving the glumes behind persisting on the stalk.

Notes:

Tufted Hairgrass, Latin name sometimes (incorrectly) spelled D. caespitosa, is a circumpolar species, present throughout much of the northern hemisphere. Throughout its range it is mostly found in wet places, in sandy or gravelly soil, but in Minnesota it is most often seen in shoreline rock crevices and ledges, such as on Lake Superior's north shore, and less often in wet meadows, prairies and the occasional calcareous fen. It is distinguished by the dense clump of stiff, erect, hairless, mostly basal leaves that are flat or involute and ribbed on the upper surface, often with perisistent old leaves; a long hairless ligule; the (usually) open, airy panicle (sometimes more compact and nodding); spikelets up to 6 mm long, single at branchlet tips with 2 florets that are long hairy only around the callus and rachilla; lemmas that are jagged along the tip, have a straight to slightly bent awn arising from below the middle that does not extend much beyond the tip of the lemma, if at all.

There are several subspecies but they are apparently poorly understood and not well documented, at least 4 of which are native to North America; the subspecies found in Minnesota is the most common, subsp. cespitosa. There are also numerous cultivars in the nursery trade, selected for flower color, cluster shape, overall size and other desirable (?) characteristics.