Achnatherum paradoxum

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 : 89

Achnatherum paradoxum (L.) Banfi, Galasso & Bartolucci ( Figure 49 (2)).

Lemma dorsal surface: Characterised by quadrangular long cells of (2–)4–18(–24) × (10–)12–16 µm, longer at the margin up to 38 µm, smooth walls 1 µm thick, of linear distribution like short cells. Short cells: main Silica cells (8–)10–14(–16) × (10–)12–14 µm, circular to ovoid, occasionally reniform, linear distribution, solitary, with cork cells, high density 30–65(–78) silica cells/ 100 µm 2; Cork cells fusiform 2–4(–6) × 10–12 µm, paired with silica cells. Spines and hairs: Hooks not studied; Prickles not studied; Macro-hairs 180–290(–340) µm long, circular to ovoid base (8–)10–18(–20) × 9–19 µm, irregularly distributed.

Lemma apical surface: Characterised by long cells similar to those of the dorsal area. Short cells: Silica cells equal in size, distribution, and morphology, at higher density than dorsal area cells 50–85(–92) silica cells/ 100 µm 2; Cork cells of equal size, morphology, and distribution. Spines and hairs: Hooks not studied; Prickles circular to ovoid base (8–)14–19(–22) × 16–22(–26) µm, up to 50 µm long, solitary, of linear distribution in dorsal part of apex, density <2 prickles/ 100 µm 2; Macro-hairs of equal size, morphology and distributed all across lemma apical surface, being more frequent at lowest part of apex.

Awn base surface: Long cells (85–)90–140(–164) × (7–)8–10(–11) µm, extremes rounded, sinuous walls to 3 µm thick, linear distribution. Short cells: Silica cells circular (8–) 9–12(–14) µm, paired with cork cells, in lines, never solitary; Cork cells quadrangular 5–7(–9) × 8–12 µm, paired with silica cells. Spines and hairs: Prickles ovoid to lanceolate base 26–45(–52) × 18–28(–30) µm and up to 52 µm long, linear distribution. Stomata paracytic (parallel cell walls), between lines of prickles 8–16 µm long, density (2–)3–7(–8) stomata/100 µm 2.

Material studied: Morocco: Bou Nacer, 1810 m.a.s.l., 16-VII-2011, M . Chamboleyron , ECWP n.n.; Midelt , 2030 m.a.s.l., 14-VI-2018, M . Chamboleyron , ECWP n.n.

Figures

FIGURE 49. Lemma surface Achnatherum bromoides (1) and Achnatherum paradoxum (2). A. Lemma central dorsal surface view. B. Lemma margin dorsal surface view. C. Lemma apex surface. D. Awn surface. lc. Long cell. sc. Silica cell. cc. Cork cell. h. Hook. p. Prickle. mh. Macro-hair. s. stomata. Bars indicate 100 µm.