| # Festuca of North America |

S.G. Aiken, M.J. Dallwitz, C.L. McJannet, and L.L. Consaul

### Festuca gigantea (L.) Vill.

GIANT FESCUE.

Hist. Pl. Dauph. 2: 110. 1787. Bromus giganteus L. Sp. Pl.: 77. 1753. Lolium giganteum (L.) Darbysh., Novon 3: 241. 1993. Type: Prussia. Silesia: habitat in pratis pinquioribus cum Fest. elatiore, sed rarius obvenit, et magis locis montanis, quam declivibus crescit.

More extensive synonymy in the Catalogue of New World Grasses. R.J. Soreng, Project Leader, US.

Habit. Plants deep green, 45–150 cm high, not densely tufted (bases small), tiller bases stiffly erect (sometimes slightly decumbent), bases not purplish, horizontal rooting stems absent. Vegetative shoots arising outside, or breaking through the base of existing sheaths.

Vegetative morphology. Sheaths glabrous or glabrescent or with trichomes (that are scaberulous and retrorse), not conspicuous at the base of the plant (usually brownish), splitting between the veins (slowly) or remaining entire, not conspicuously splitting between the veins, open more than half their length. Collars glabrous. Auricles present, claw-like. Auricular cilia absent. Ligules 0.5–2.5 mm long, without cilia. Leaf blades 10–50 cm long, more or less lax. Adaxial blade surfaces glabrous or with trichomes (not prominently ridged from underlying veins, with scabrid margins), abaxial blade surfaces glabrous (glossy). Leaf blades flat, 6–18 mm wide. Veins 26–36. Adaxial to abaxial sclerenchyma strands present. Uppermost culm leaf sheaths not inflated. Flag leaf blades 10–20 cm long. Culm nodes never exposed (rarely) or becoming exposed; internodes glabrous.

Floral morphology. Inflorescence paniculate (lax and nodding), 8–50 cm long. Inflorescence branches at the lowest node 2 (unequal, the shorter branch with 3–6 spikelets, the longer with 6–9 spikelets), appressed after anthesis, 5–10 cm long. Rachis angular in cross section, trichomes mainly on the ridges. Spikelets aggregated towards the ends of the branches; 3–9 on the longest branches; 8–13(–20) mm long, 1.5–2.5 mm wide. Proliferating spikelets absent (not recorded for this taxon). Florets 3–10. Glumes unequal (approaching subequal), glabrous or with trichomes, vestiture at the apex only, margins not ciliate (broadly hyaline). First glume 4–7 mm long, veins 1. Second glume shorter than the first lemma, 5–8 mm long, veins 3. Rachilla internodes antrorsely scabrous (sparsely). Lemma callus not elongated. Lemma 6–9 mm long (ovate, lanceolate), nerveless in dorsal view or sometimes with only the centre vein distinct, with trichomes, trichomes on the upper portion only (particularly on the veins); apex entire. Lemma awn 10–18 mm long. Palea 6–9 mm long, glabrous between the keels. Lodicules with marginal teeth, ciliate (slightly), 0.9–1.1 mm long. Anthers 2.5–3 mm long. Ovary apex glabrous.

Cytology. 2n = 42.

Habitat and distribution. Introduced; limited, probably accidental introduction. Canada: Que. (found at two sites in southern Quebec, Dubé and Morisset 1983), Ont.; Northeastern USA: Mich., N.Y. (adventive in New York at Dobb's Ferry and the New York Botanical Garden; there is also, one record in Michigan, S.J. Darbyshire, personal communication 1994).

Classification. Subg. Schedonorus (Beauv.) Peterm. (sect. Plantynia (Dumort) Tzvelev (Tzvelev 1976)).

Notes. The transfer of this taxon to Lolium (Darbyshire 1993) was evaluated in Aiken et al. (1997).

Information in the above description is based on: the few specimens that have been collected in North America, European specimens at CAN, and the description given by Markgraf-Dannenberg (1980).

Festuca gigantea is highly self-fertile and thus the taxon contrasts with most other fescues (Beddows 1931).

Illustrations. • Herbarium specimen: CAN. Duplicate specimen of F. gigantea from one of two collection sites in Quebec, known in 1995. • Distribution map

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations with detailed captions, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa. See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Aiken, S.G., Dallwitz, M.J., McJannet, C.L. and Consaul, L.L. 1996 onwards. Festuca of North America: descriptions, illustrations, identification, and information retrieval. Version: 14th February 2019. delta-intkey.com’. Aiken, Dallwitz, McJannet, and Consaul (1997) should also be cited (see References).

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