Stipa alba F. M. Vazquez & S. Ramos 2007

Stipa × alba F.M. Vázquez & S. Ramos (Figure 58 (1)). Lemma dorsal surface: Characterised by long rectangular cells of (19–)22–55(–62) × (8–) 10–18(–21) µm, sinuous walls up to 10 µm thick, linear distribution. Short cells: Silica cells of 8–12 × 5–11 µm, circular, obovate to oblong, in pairs or threes with hook, or less frequently, cork cells, situated between long cells, never solitary; Cork cells (2–)3–9(– 11) × 7–10 µm, reniform to oblong, sporadic, always with a silica cell. Spines and hairs: Hooks rectangular to circular base (8–)10–19(–21) × 4–7(–8) µm high, regularly distributed between long cells, in pairs or threes with silica, cork or additional hook cells, more frequently solitary, density 12–15 hooks/ 100 µm 2; Macro-hairs 400–550(–740) µm long, circular base 8–21(–24) µm, regularly distributed in rows from mid-dorsal to base of lemma. Lemma apical surface: Characterised by long cells similar to those of the dorsal area, slightly longer, up to 70 µm and up to 14 µm thick. Short cells: Silica cells of 6–12 × 8–11 µm, more frequent, similar in distribution and morphology to the dorsal; Cork cells (2–)3–7(–9) × 7–10 µm, oblong to reniform, equal distribution to the dorsal. Spines and hairs: Hooks circular base 10–19(–22) µm, denser than at the dorsal area 18–22 hooks/100 µm 2; Prickles circular base 22–35 µm and up to 140 µm long, distributed at middle of apex; Macro-hairs of obovate to circular base (15–)21–32 × 10–14(–18) µm and up to 340 µm long, located at middle and distal parts of apex. Material studied: Tunisia: Beni M’Hira, near to Tataouïne, 10°49′W, 32°57′N, IV-1996, M. Visser (Holotype – HSS 11867).