Najas tenuifolia subsp. tenuifolia Magnus

Leaves 2-3.75 cm by 0.6-1.3 mm, on either side with 14-40 (dark) brown spiny teeth. Sheaths on either side with 6-17 spines. Spathe of male flowers 2.8-3.8 mm, neck 0.7-0.9 mm, bearing up to c.0.3 mm long spine-cells; anther 2-2.5 by 0.8-1.1 mm. Female flowers 2.3-3(-3.5) mm; ovary 0.8 by (0.25-)0.3 mm; stigmas 0.6-0.8(-1.2) mm. Seeds 2-2.3 by 0.7-0.75 mm; testa with 26-36 length-rows of 35-40 subquadrate or 5-6-angular areoles.