Herb, up to 70 cm diam., forming loose to compact mats. Leaves up to 32(— 40) × 1.6 mm; lamina narrowly lanceolate to near linear, slightly sinuate and/or falcate; adaxial and abaxial surfaces green, base of lamina and petiole often mottled, slightly glossy; adaxial surface concave; abaxial surface convex; apex subacute to acute; base attenuate; petiole indistinct; old leaves yellow. Involucral leaves 1.5—2.1 × 1.8—2.0 mm, green; sometimes with a small lateral fold; apex subacute to obtuse. Flowers 8.0—12.0 mm diam. Tepals 4.2— 7.0 × 1.7—2.5 mm, narrowly elliptic to elliptic, white, not overlapping; apex subacute to obtuse, sometimes with a small v-notch; claw weakly differentiated. Nectary yellow. Filaments 2 .5—3.0 mm long, < ½ tepal length, white. Anthers 0.6—0.9 × 0.4—0.5 mm, pink to pink-red. Ovary 0.4—1.0 × 0.6—0.8 mm, obovoid, green; sutures prominent. Style 2.0— 2.5 mm long; slightly bulbous at base, white with base flushed green. Stigmatic branches 1.0—1.8 mm long, white, curved across each other prior to spreading. Capsule 2.2—2.7 × 1.7—2.2 mm. Seeds 1.1—1.5 × 0.9—1.4 mm, smooth to slightly rugose, brown to red-brown, occasionally dark brown. FL Oct—Feb; FT Nov—Apr.

A N. calycina foliis tenuioribus, sinuolatis, interdum falcatis, tepalis ellipticis, filamentis brevioribus, ovario suturas prominente s habente, cruribus stigmatis primum curvatis deinde divergentibus, habitatione in rivis rivulisque distinguenda.