Herb, forming loose t o compact mats of stems and leaves; frequently intertwined with other herbs. Leaves up to 30(–90) × 1.2(–1.5) mm, linear; lamina linear, sometimes slightly falcate, adaxial and abaxial surfaces green to green-brown, sometimes mottled, slightly glossy; adaxial and abaxial surfaces ± flat; apex subacute to acute; petiole and lamina indistinct; old leaves yellow. Involucral leaves 1.0–1.8 × 1.7–1.8 mm, green; sometimes with a small lateral fold; apex obtuse. Flowers 6.0–10.0 mm diam. Tepals 3.2–5.5 × 2.0– 3.1 mm, broadly elliptic to obovate, white, usually overlapping; apex obtuse to subacute, sometimes with a small notch; claw weakly differentiated. Nectary yellow. Filaments 2.2–3.4 mm long, > ½ tepal length, white, sometimes flushed pink. Ovary 0.6–0.65 × 0.6–0.75 mm, obovoid, green; sutures often with a slight red flush, rarely prominent. Style 1.6-1.8 mm long; white with base often flushed red. Stigmatic branches 1.4-1.7 mm long, white, straight prior to spreading. Anthers c. 0.5 × c. 0.3 mm, pink to pink-red. Capsule 1.5-1.8 × 1.3-1.8 mm. Seeds 0.9-1.0 × 0.8-0.9 mm, slightly to moderately rugose, dark brown to black. FL Nov-Feb; FT Dec-Mar.

A N. calycina foliis angustis, linearibus, tenuioribus, ovario et capsula et seminibus minoribus, base styli atque apice ovarii plerumque rubrotincto, habitatione in marginibus lacuum atque ad lacunas montanas ordinate inundatas distinguenda.