Flower:

Panicle at the top of the stem, up to 5(8) inches long, the branches usually erect to ascending, the lowest branches sometimes spreading, with 1 to 3 branches per node, the lowest branches with 2 or more spikelets (flower clusters). Spikelets are short-stalked, light green to reddish at flowering time, 9 to 14.5 mm (to ½+ inch) long, flattened, lance-elliptic in outline and usually have 5 to 8 florets; the floret at the tip may be sterile.

At the base of a spikelet is a pair of bracts (glumes), both awnless, hairless, shorter than the spikelet, pointed at the tip, not keeled, the lower glume 3 to 4.5 mm long and 1-veined, the upper glume 3-veined, 4 to 6.4 mm long. Florets are surrounded by a pair of bracts (lemma and palea), the lemma green to reddish, obscurely 5-veined, not keeled, 4 to 8 mm long excluding a straight, .5 to 4-mm awn, the lowest lemma somewhat larger than the upper glume; the palea is about as long as the lemma, 2-veined, often sparsely hairy across the tip end. Sterile florets are like the fertile but underdeveloped.

Leaves and stems:

Leaves are mostly basal, mostly folded, sometimes flat, 4 to 16 inches (to 40 cm) long, .5 to 2 mm wide when folded, have (3)5 to 7(9) conspicuous ribs, are hairless or minutely hairy near the base or on the ribs. Basal sheaths are red when young, soon disintegrating and shredding into fibers. Sheaths of new shoots (tillers) are green, hairy, and the edges fused for at least 75% of their length (closed sheath) but are fairly fragile and can easily split.

The 1 to 3 stem leaves are flat or folded and shorter than basal leaves. Stem leaf sheaths are mostly hairless and not necessarily fused for most their length like tiller sheaths are. The ligule (membrane where the leaf joins the sheath) is .1 to .5 mm long, ragged along the top edge and lacks a fringe of hair. Nodes are hairless and exposed. Stems are hairless, multiple from the base, erect to ascending or prostrate from the base and rising at the lowest node. Plants form loose to dense clumps from shoots that run horizontally for a short distance before rising (extravaginal), and also form colonies from elongated rhizomes.

Fruit:

The panicle branches typically become erect when spikelets mature, drying straw-colored. Florets drop off individually as they mature, leaving the glumes persisting on the stalk. Grains (seeds) are brown, oval-elliptic.

Notes:

Red Fescue has a long history of being planted as turf grass and forage. In Minnesota, outside of cultivation it is most often found in the disturbed soils of roadsides, agricultural fields, grassy banks and shores, usually in open ground. There are at least 10 subspecies, some native to parts of North America, others to Europe and/or Asia, but none are considered native to the Midwest. The DNR lists two subspecies in Minnesota, subsp. rubra and subsp. fallax; there are no records of fallax in the state, but it's been recorded in Wisconsin so it's possible some of the records that are not IDed to subspecies are fallax. Subsp. fallax is introduced from Europe; there are conflicting accounts about the origin of subsp. rubra but most sources consider it introduced to North America from Eurasia. It is likely far more widespread in Minnesota than herbarium records indicate.

With 10+ subspecies, it goes without saying that Festuca rubra is a variable species, the subspecies differentiated by whether it is rhizomatous or not, various leaf characteristics, hairiness, lemma length, anther length, habitat, and other traits. There are also hybrids and cultivars in wide use to add more variations into the mix. Subsp. rubra is generally distinguished by having rhizomes and forming clumps; sheaths of tillers (new shoots) hairy and closed for at least 75% of their length, basal sheaths tinged red and becoming fibrous with age; leaves mostly basal, flat or folded, .5 to 2 mm diameter when folded; panicle branches usually ascending to erect, sometimes spreading; spikelets with (4)5 to 8(10) florets, green to reddish, lemma awns to 4 mm long. Subsp. fallax is similar but has broader leaves, to 7 mm wide, that are usually flat.

There are 3 narrow-leaved Festuca species in Minnesota, the others are the native F. saximontana and non-native F. trachyphylla, and they can be difficult to distinguish. F. rubra is the only one of the three that has rhizomes, reddish basal sheaths, old sheaths shredding into fibers, and extravaginal shoots where new shoots break through the sheath and grow horizontally for a bit before rising up, but these traits are not so obvious without digging some out and careful picking through the clump. F. saximontana and F. trachyphylla both form more dense clumps than F. rubra, the shoots all growing erect from the sheath, and tend to have fewer florets per spikelet, though there is overlap. Also, their tiller sheaths are mostly hairless and fused for not more than half their length, which is best seen while they're still green and relatively fresh, and easier to determine without digging up a clump. Don't bother looking at stem leaf sheaths—it's the tiller sheaths that are distinctive and some should be intact as long as they're still green.

A characteristic of Festuca species is what's known as “sclerenchyma strands”, which are clusters of hardened, dead cells that run the length of the leaf just under the surface, the shape and arrangement of which are fairly distinct for each species. These cannot be seen with the naked eye and requires putting a cross-section of the leaf under a microscope. Try as I might I was not able to get a photo of this myself, but some images are out there in the web universe and Flora of North America has some illustrations online that are helpful, in case you are able to get a leaf under a scope to see for yourself. Festuca rubra subsp. rubra has small round to elliptic strands, one at each edge, 3 to 5 on the lower leaf surface (1 opposite each vein) and none on the upper surface. Subsp. fallax has 5 to 9 strands, including some on the upper surface. F. saximontana and F. trachyphylla strands may run along most or all of the lower surface as a continuous or interrupted band.