Isoetes alstonii C. F. Reed & Verdc.

Fischer, Eberhard & Lobin, Wolfram, 2022, The genus Isoetes (Isoetaceae) in Central Africa (Democratic Republic of the Congo, Rwanda, Burundi) with the description of three new species, Willdenowia 52 (3), pp. 315-334 : 316

Isoetes alstonii C. F. Reed & Verdc. in Kirkia 5: 19. 1965. – Holotype: Zimbabwe, Victoria Falls, S bank in front of main falls, under the spray of the main falls, 29 Aug 1947, Greenway & Brenan 8012 (EA [not seen]; isotype: K000351301 ).

Description — Megaspores 400–520 × 480–520 µm; proximal face trilete, densely tuberculate-pustulate, with large projections 30–60 µm in diam. and up to 20 µm high, and smaller projections 19–22 µm in diam., with dense threads covering tubercles and most of pustules, ridges up to 30 µm wide and up to 40 µm high; distal face with few large and distant pustules 40–60 µm in diam. and up to 20 µm high, and small tubercles 20–30 µm in diam., tubercles with short and dense threads, pustules free of waxes. – Fig. 3.