C. crispatula Engl. var. tonkinensis (Gagnep.) Jacobsen, stat. et comb. nov.

C. tonkinensis Gagnep., Not. Syst. 9:133 (1941). - C. retrospiralis (Roxb.) Kunth var. tonkinensis (Gagnep.) De Wit, Aquarienpflanzen, p. 189 (1971). - Lectotype (selected by Rataj, 1975): Balansa 2045, Baa Toi, Aug. 1887 (P). Paratype: Balansa 2044, Baa Toi, 8.2.1887 (L, P). - Another paratype: Balansa 2043, Riviere Noire, 29.11.1887 (L, P) represents var. crispatula and is drawn in De Wit (1983), Fig. 51.

Leaves 20 - 30 cm long, 0.2 - 0.4 cm broad, flaccid, green to brownish, smooth or slightly undulate, usually submerged (Fig. 7 I). Spathe with a long tube, 15 - 30 long, limb with an open spiral (?).

Notes: Var. tonkinensis is the variety with the most narrow leaves of all, viz. 0.2 - 0.4 cm broad, completely flaccid, unable to carry themselves, showing that it is almost constantly submerged. Var. tonkinensis is only rarely seen in cultivation and most of the cultivated plants referred to as "tonkinensis" represent var. crispatula or var. flaccidifolia.

Var. tonkinensis is found in northern Thailand and in northern Vietnam.