Festuca of North America
| Festuca of North America |
|
Nomenclature
TEXAS FESCUE.
Grasses N. Am. 2: 589. 1896. Festuca texana Vasey, Bull. Torrey Bot. Club 13: 119. 1886, non Steud. Syn. Fl. Glum. 1: 310. 1854. Festuca obtusa var. versuta (Beal) St.- Yves, Candollea 2: 280. 1925. Type: U.S.A. Texas: "shades, upper Llano", 1884, J. Reverchon 1618. Isotype: US!
F. nutans var. johnsonii Vasey, Contrib. U.S. Natl. Herb. 2: 548. 1894. F. johnsonii (Vasey) Piper, Contrib. U.S. Natl. Herb. 10: 35. 1910. Type: U.S.A. Texas: Hamilton Co., 1886, Johnson, s.n. Holotype: US!
Habit. Plants bluish gray green or deep green (at least sometimes, with slender, glabrous culms, leaves mainly on the culms), 50–100 cm high, not densely tufted, tiller bases stiffly erect, bases purplish or not purplish, horizontal rooting stems absent. Vegetative shoots arising outside, or breaking through the base of existing sheaths.
Vegetative morphology. Sheaths glabrous or glabrescent (lower sheaths with retrorse hairs), not conspicuous at the base of the plant, splitting between the veins, open more than half their length. Collars glabrous. Auricles represented by distinct, erect, swellings or absent. Auricular cilia absent. Ligules 0.5–1 mm long, without cilia (sometimes erose, but without defined trichomes). Leaf blades 20–25 cm long, more or less lax. Adaxial blade surfaces glabrous or with trichomes (or scabrous), abaxial blade surfaces glabrous. Leaf blades flat (or loosely involute), 2–9 mm wide. Veins 15–35 (internerve distance about 2 times the width of the veins). Adaxial to abaxial sclerenchyma strands present. Abaxial sclerenchyma poorly developed, in discrete, relatively narrow strands opposite the veins. Uppermost culm leaf sheaths not inflated. Flag leaf blades (5–)10–25 cm long. Culm nodes becoming exposed, 3; internodes glabrous.
Floral morphology. Inflorescence (8–)10–30(–40) cm long. Inflorescence branches at the lowest node 2 (pulvinate at the base and flexuous), spreading, 5–12 cm long. Rachis angular in cross section, trichomes mainly on the ridges or trichomes over the entire surface. Spikelets loosely scattered in an open panicle with slender branches (spikelets borne towards the ends of the branches); 5–15 on the longest branches; 6–9(–11) mm long, 2–3.5 mm wide. Proliferating spikelets absent (usually, two specimens, US 1258476 and MO 852950, have proliferating spikelets). Florets 2–5. Glumes subequal or unequal, with trichomes, vestiture over most of the outer surface (at least on the midvein), margins not ciliate. First glume 4–6(–7) mm long, veins 1. Second glume as long as the first lemma, or almost as long, 5–7 mm long, veins 3. Rachilla internodes glabrous, or nearly so or antrorsely scabrous. Lemma callus not elongated (rounded on the back). Lemma (5–)5.5–7(–8) mm long, nerveless in dorsal view or sometimes with only the centre vein distinct, glabrous (apex sometimes slightly scaberulous on the midvein); apex entire. Lemma awn absent (or apex mucronate). Palea 5–7(–8) mm long, distinctly pubescent between the keels. Lodicules with marginal teeth, glabrous, 0.8–1 mm long. Anthers 2–3 mm long. Ovary apex pubescent. Caryopsis 2.5–3(–3.5) mm long.
Cytology. 2n = unknown.
Habitat and Distribution. Native; forest and woodland (moist, shaded sites, rocky hill sides, and mountains). North Central USA: Okla.; South Central USA: Tex.
Classification. Subg. Subulatae (Tzvelev) E. B. Alexeev, sect. Obtusae E. B. Alexeev (Placed in subg. Drymanthele, sect. Texanae E. B. Alexeev (Alexeev 1980)).
Notes
Aiken and Lefkovitch (1993) stated that in the course of their study it had become apparent that F. versuta may have affinities with subg. Obtusae rather than monotypic status in subg. Drymanthele sect. Texanae as Alexeev (1980) had suggested. Although the spikelet lengths of many specimens of F. versuta are conspicuously larger than those of the other two species in subg. Obtusae, small specimens overlap in size with large specimens of F. paradoxa Desv. and F. subvertillicata (Pers.) E. B. Alexeev. The spikelet shape in F. versuta approaches that of large specimens of F. subverticillata, while spikelet widths and their arrangement on the inflorescence branches are often similar to those of F. paradoxa. In the analyses of this database, the two nearest neighbours of F. versuta are F. paradoxa and F. subverticillata, and the three taxa group together in phenograms (Aiken et al. 1997).
Illustrations
• Line drawing. Illustration from Piper (1906) as F. johnsoni Vasey. • Holotype specimen of name in synonymy, US. Holotype specimen of F. nutans var. johnsonii Vasey. Collected: Texas: Hamilton Co., 1886, Mr. Johnson, s.n. Photocopy of specimen. Annotated by E.B. Alexeev. • Distribution map
The interactive key provides access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting specified attributes, and summaries of attributes within groups of taxa.
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: 19th October 2005. http://delta-intkey.com’. Aiken, Dallwitz, McJannet, and Consaul (1997) should also be cited (see References).
