Flower:

A single tightly packed, narrowly elliptic to cylindric, spike-like branching cluster at the top of the stem, ½ to 2¾ inches long. Spikelets (flower clusters) are 1.8 to 3.1 mm (to 1/8 inch) long, flattened, narrowly oblong-elliptic in outline and have a single floret, light green to yellowish at flowering time. Florets bloom from the top of the spike down, those at the tip of the spike may be forming fruit while those at the base are just coming into bloom.

At the base of a spikelet is a pair of bracts (glumes), both similar, fused together on the lower fourth to third, 3-veined, long-haired along the keel and edges, 1.8 to 3.1 mm long, egg-shaped with a pointed tip. Florets are surrounded by a pair of bracts (lemma and palea), the lemma as long as or shorter than the glumes, 5-veined, hairless, and with an awn arising from the near the base of the midvein, the awn 3 to 5 mm long, extending well beyond the tip of the glumes, initially straight becoming bent at maturity; the palea is obscure or absent.

Leaves and stems:

Leaves are basal and alternate, erect to ascending, 1 to 6 inches long, 1 to 4 mm (to 1/6 inch) wide, lance-linear, mostly flat. Basal leaves are longest; stem leaves are few and much shorter but long-sheathing. Sheaths are hairless, the lower tightly wrapping the stem, the upper often more inflated and loose, and may be blue-green in color. The ligule (membrane where the leaf joins the sheath) is membranous, 3 to 7 mm long, straight across or convex at the tip, and not fringed with hairs. Nodes are smooth, green to orange. Stems are hairless, erect to ascending, multiple from the base, forming dense clumps.

Fruit:

Spikelets turn lead gray at maturity, the entire spikelet shedding as each grain matures, leaving the naked stalks behind. Grains (seeds) are 1 to 1.4 mm long.

Notes:

Carolina Foxtail is a cool-season grass present in much of the US and into western Canada. While its habitat is generally noted as open meadows, shores, wetland edges, wet ditches, and clearings in floodplain forest, in Minnesota it is almost exclusively found in or near rock outcrops, primarily in the Minnesota River Valley, and almost always associated with vernal pools. It is vaguely similar to Little Barley (Hordium pusillum), with which it may grow, but which has much larger spikelets, glumes that are awned and hairless, and shorter ligules.

There are 4 Alopecurus species known to be in Minnesota; A. carolinianus is one of two natives. At a glance they may all look similar—narrowly cylindric spikes usually blooming (and completely shedding seed) from the top down, single-flowered spikelets usually blackish when mature, hairy glumes equal in size and shape, and lemma awns arising from the lower half of the lemma—but the size of the spikelet combined with length of the awn can help determine a correct ID. Carolina Foxtail is the smallest of these four, usually under 12 inches tall, has small spikelets (3mm or less) and conspicuous awns that extend well beyond the tip of the spikelet.

Of the other Alopecurus species in Minnesota, Meadow Foxtail (A. pratensis) is the only other with such conspicuous awns, but is a much larger plant with spikelets up to 6 mm long. Of the other species with spikelets under 3.5 mm, all have shorter awns that only slightly extend beyond the tip of the glumes, if at all.