Achnatherum Beauvois (1812: 19

Vázquez, Francisco Maria, Márquez, Francisco, García, David & Oualidi, Jalal El, 2025, A taxonomic revision of Stipeae s. l. tribe (Poaceae) in N Africa, Phytotaxa 699 (1), pp. 1-174 : 20-26

Achnatherum Beauvois (1812: 19 (146)).

Type:— A chnatherum bromoides ( L.) Beauvois (1812: 146).

Perennials, stoloniferous, simple panicle poorly ramified, long to short peduncle. Flowers glumes sub-equals, lemma apex with dents to truncate, homogeneous pubescence, not involved margins; anthers apex smooth; callus obtuse; awn not geniculated, scabrid, short.

Key to the Achnatherum species.

1. Awn curved, base pubescent. Lemma with hairs 1.5–3 mm ................................................ A. calamagrostis subsp. mesatlasicum .

- Awn straight, base scabrid to smooth. Lemma with hairs 0.3–1 mm .............................................................................................. 2.

2. Awn 15–27 mm. Callus 0.4–1 mm .............................................................................................................................. A. bromoides .

- Awn 12–16(18) mm. Callus 0.2–0.4 mm ................................................................................................................... A. paradoxum .

1. Achnatherum bromoides (L.) P. Beauvois (1812: 20) ( Figure 4 & 5 ).

Type:— FRANCE. Habitat Monspelii. Gouan s.n. [lectotype LINN 84-4 !, designated by Vázquez et al. (1995: 183)] .

≡ Agrostis bromoides Linnaeus (1767: 30) . (Bas.) [lectotype LINN 84-4!, designated by Vázquez et al. (1995: 183–184)]. ≡ Aristella bromoides ( L.) Bertoloni (1834: 690).

≡ Stipa bromoides ( L.) Dörfler (1897: 129).

≡ Lasiagrostis bromoides (L.) Nevski & Roshevitz (1934: 72).

= Stipa aristella Linnaeus (1768: 229) . [lectotype LINN 94-6 !, designated by Vázquez et al. (1995: 183–184)].

= Andropogon hermaphroditum Pourret (1788: 308) . [lectotype n.v.].

= Agrostis stipata Koeler (1802: 77) . [lectotype n.v.].

= Calamagrostis gracilis Seenus (1805: 73) . [lectotype n.v.].

Culm to 160 cm, erect, glabrous; prophylls to 14 mm, striate surface, smooth. Leaves with sheaths glabrous, smooth at the throat, especially on the innovations, nearly glabrous on the stem, free margin, ciliated; ligule short, decurrent, 0.1– 0.6 mm long, apex truncated, scabrid; vegetative blades, culms to 75 cm long, plane to involute, abaxially glabrous or sometimes scaberulous, adaxially scabrous to villous striated, scabrous-ciliate on the margin, to 6 mm wide extended lamina; fertile blades culms to 37 cm long, plane to involute, abaxially smooth, adaxially scabrous to villous, striated, scabrous-ciliate on the margin, up to 5 mm wide when extended lamina, ca. 1.4 mm wide when rolled, rigidly sharp-pointed rounded. Inflorescence panicle to 50 cm long, lineal to fusiform, erect to falling, loose, the axis glabrous, distant alternate branches, slender, smooth to scabrous, smooth below, spikelet-bearing in the upper half. Spikelet sub-adpressed when mature, or free along the branches when immature or flower, the lateral pedicel 10–25 mm long, smooth to scabrid; glumes lanceolate, sub-equal, 8–19 mm long, hyaline, green to occasionally purple with hyaline acuminate tips, 3 ribs, smooth to scabrid in ribs; lemma slender, fusiform, 6–10.5 mm long, homogeneous pilosity, apex with two lateral dents to 0.9 mm; callus gross, short and rounded apex, 0.4–1 mm long, villous with adpressed hairs; palea lanceolate 3.5–7 mm, dorsally villous, with line of flexuous hairs up to 2 mm; awn straight to unigeniculate, 15– 27 mm long, persistent, twisted, scabrid to villous angles with ascending hairs ca. 1.2 mm long; lodicules 3, unequal, the two laterals to 3.5 mm long with acute apex, the posterior to 2.5 mm long with acute apex; anthers 2.7–6 mm long, apex smooth; stigma 2, plumose. Caryopsis fusiform, 4–8 mm long, brown to dark brown ( Figure 5 ).

Phenology:—Flowering May–July.

Habitat:—Wooded areas in cool places, especially in holm oak forests, on calcareous soils with rainfall above 500 mm per year.

Distribution:—[Mediterranean-Turanian]. In North Africa: Morocco ( Figure 4 ). To be confirmed in Algeria.

Notes:—The presence of this species in Algeria has not been confirmed since its sole citation by Ball (1878: 711). It was not found there by Maire (1953: 68), and no herbarium sheet from Algeria was found in this study.

2. Achnatherum calamagrostis subsp. mesatlasicum (Quézel) Dobignard (2010: 440) . ( Figure 4 & 6 )

Type:— MOROCCO. Bou Naceur : vallée des Beni Ouriach. Pujos s.n. [holotype RAB020112 !] .

≡ Calamagrostis argentea subsp. mesatlasica Quézel (1954: 299) . (Bas.)

≡ Achnatherum mesatlasica (Quézel) Ibn Tattou (1998: 212) .

Culm to 90 cm tall, erect, glabrous; prophylls to 12 mm, striate surface, smooth. Leaves with sheaths scabrid to glabrescent, smooth on the innovations, nearly glabrous on the stem, free margin, ciliated; ligule short, decurrent, 0.2–0.8(–1) mm long, truncated, scabrid; vegetative blades culms to 45 cm long, plane to involute, abaxially and adaxially scabrid, scabrous on the margin, to 14 mm wide extended lamina; fertile blades culms to 25 cm long, plane to involute, abaxially and adaxially scabrous, striated, scabrous on the margin, to 6 mm wide when extended lamina, ca. 1.5 mm wide when rolled, sharp-pointed acute Inflorescence panicle to 20 cm long, lanceolate to oblong, pendule to erect, loose, the axis glabrous, distant alternate branches, slender, smooth to scabrous, smooth below, spikelet-bearing in the upper half. Spikelet distant and lax when mature, or free along the branches when immature or flower, the lateral pedicel 12–32 mm long, scabrid; glumes lanceolate, sub-equal, (5.5–) 6–7 mm long, hyaline, green pale brow with hyaline short acuminate tips, 3 ribs, smooth to scabrid ribs; lemma slender, fusiform, 2.5–3(–3.4) mm long, homogenously villose with hairs up to 3 mm, apex with two lateral dents up to 0.4 mm or absent; callus gross, short and acute apex, 0.2–0.4 mm long, villous with adpressed hairs; palea lanceolate 2–3.5 mm, dorsally villose; awn unigeniculate, 0.6–0.9(–1) cm long, persistent, twisted, base plumose, rest scabrid angles; lodicules 3, unequal, the two laterals to 1.7 mm long with acute apex, the posterior to 2.1 mm long with acute apex; anthers 2–2.7 mm long, apex apiculated not bearded; stigma 2, plumose. Caryopsis fusiform, 1.7–2.4 mm long, brown ( Figure 6 ).

Phenology:—Flowering June–August.

Habitat:—In degradated areas of Juniperus and Quercus forest, mostly stony with sparse chamepehytes and grasses on calcareous soils.

Distribution:—[Stenomediterranean-Maroccan]. Endemic to Jbel Bou Naceur (Middle Atlas, Morocco) ( Figure 4 ).

Notes:—As observed by Quézel (1954), Moroccan specimens differ from the European A. calamagrostis (L.) P. Beauv. subsp. calamagrostis in the morphology of the glumes, awn and panicle. Note especially the flower parts as small as glumes up to 7 mm, vs. 8 mm, lemma up to 3, 4 mm vs. 4, 5 mm, palea 2–3 mm vs. 3–4 mm or the awn 0,6–0,9(1) cm vs. 1–1,4 cm and anthers 2–2,7 mm vs. 2,5–3,4 mm in the type subspecies, together with the reduction, even to absence of lemma apex auricles which show a clear separation between both taxa (including in the southern Iberian populations from the Carzola and Sierra Nevada mountains ( Gómez, 2011; Pérez-Latorre et al., 2015)).

3. Achnatherum paradoxum (L.) Banfi, Galasso & Bartolucci (2018: 18). ( Figure 4 & 7 )

Type:— FRANCE. Habitat in Galloprovincia , G. Narbonensi. Sloane 96 [lectotype BM-SL!, designated by Freitag (2000: 243)]. ≡ Agrostis paradoxa Linnaeus (1753: 62) . (Bas.)

≡ Milium paradoxum ( L.) Linnaeus (1759: 872), & Scopoli (1771: 58), nom. illeg.

≡ Piptatherum paradoxum ( L.) Beauvais (1812: 18).

≡ Oryzopsis paradoxa (L.) Nuttal (1823: 128) & Trabut (1895: 167).

≡ Stipa paradoxa (L.) Raspail (1825: 449).

≡ Urachne paradoxa (L.) Link (1827: 92).

≡ Urachne linnaei Trinius & Ruprecht (1842: 12) , nom. superfl.

≡ Oryzopsis paradoxa var. eriolemma Maire (1941: 220) , nom. superfl ..

= Milium nigrum Lamarck (1779: 568) . [lectotype n.v.].

= Agrostis melanosperma Lamarck (1783: 58) . [lectotype n.v.].

= Milium scopolianum Willd. ex Steudel (1841: 146) , pro syn.

= Piptatherum virescens Bubani (1900: 294) , nom. illeg., non Boissier (1884: 507).

= Oryzopsis paradoxa var. leiolemma Maire (1941: 220) . [lectotype n.v., paratype: P03239230 !, designated here].

Culm to 140 cm, erect or somewhat geniculate at base, glabrous, occasionally scabrous; prophylls to 16 mm, acute, striate surface, scabrid to pubescent. Leaves with glabrous sheaths, free margin, ciliated to glabrous; ligule thin, decurrent, 0.3–1.2 mm long, glabrous, apex truncated with two tufts of hairs in the base; vegetative blades culms to 45 cm long, plane to involute, abaxially and adaxially glabrous or sometimes scaberulous, scabrous on the margin, to 12 mm wide extended lamina; fertile blades culms to 25 cm long, plane to involute, abaxially and adaxially glabrous to scabrid, margin scabrous, to 10 mm wide when extended lamina, ca. 3.5 mm wide when rolled, flexuous apex acute. Inflorescence panicle pyramidal, downfall, loose, 14–35(–45) cm long, the axis scabrid, the branches in distant verticils, slender, flexuous, scabrous, spikelet-bearing in the upper half, the lowermost ca. 3–8 cm long, the lower internode of the axis as much as 22 cm long. Spikelet open and frequently pendule branches, the lateral pedicel to 3 cm long, scabrid; glumes lanceolate, sub-equal, 7–8 mm long, green frequently to pale brown with apex rounded to acute, occasionally bifid, 3 ribs, smooth to scabrid ribs and upper half surface scabrid; lemma slender, terete, 4–4.7 mm long, homogenous pilosity to smooth when mature, excluding the apex and base smooth, coriaceous, apex truncate; callus gross, short and obtuse, 0.2–0.4 mm long, smooth; palea to 4.6 mm, dorsally pilose, margins smooth, coriaceous, apex short sub-acute; awn 12–16(–18) mm long, early deciduous, not geniculate; lodicules 3, unequal, the two laterals acute, 1 rib, apex entire 1–1.2 mm long, the posterior acute, 1 rib, apex entire up to 0.6 mm long; anthers 1.6–2.7 mm long, apex smooth; Stigma 2, flexuous, plumose. Caryopsis to 4.5 mm long, terete, fusiform, brown to pale brown ( Figure 7 ).

Phenology:—Flowering May–July.

Habitat:—Mostly in areas of cool forest and shady margins, on rich soils, especially sclerophyllous.

Distribution:—[Stenomediterranean-Occidental]. In North Africa: Tunisia, Algeria and Morocco ( Figure 4 ).

Figures

FIGURE 4. Geographic distribution of Achnatherum bromoides (red mark), Achnatherum calamagrostis subsp.mesatlasicum (blue mark) and Achnatherum paradoxum (yellow mark) in North Africa (from checked herbarium sheets and selected bibliographical data (stars)).

FIGURE 5. Achnatherum bromoides. a. Plant habitus. b. Spikelet. c. Anthecium + Awn. d. Anthecium open. e. Ligule (Sheet + Limb fractions). f. Awn fragment + awn section. g. Limb cross section. Bars indicate 1 mm in f and g; the rest 10 mm.

FIGURE 6. Achnatherum calamagrostis subsp. mesatlasicum a. Plant habitus. b. Spikelet. c. Anthecium open + Awn + Anthers. d. Anthecium section with Gynoecium. d’. Lodicules. e. Ligule (Sheet + Limb fractions). f. Awn fragment. g. Limb cross section. Bars indicate 1 mm in b, c, d, d’ and f; the rest 10 mm.

FIGURE 7. Achnatherum paradoxum. a, a’. Plant habitus. b. Spikelets. c. Anthecium + Awn. d. Ligule (Sheet + Limb fractions). e. Awn fragment. f. Awn section. g. Limb cross section. Bars indicate 1 mm in b, c, e, f and g; the rest 10 mm.