Cyperus esculentus L.
Yellow Nut Grass
Rhizomes weak, filiform, terminated by hard tubers. Stems to 40 cm high, 3-angled, leafy and ± bulbous at base. Leaves < or > stems, 3-8 mm wide, flat, pale green, margins recurved, scabrid; sheaths reddish-brown. Involucral bracts 4-6, leaf-like, lowest 1-2 > inflorescence. Inflorescence yellow-brown, a simple to compound umbel; rays c. 6, unequal, longest to 10 cm. Spikelets ± 10-15 × 2 mm, linear-oblong, much compressed, in lax ovate spikes at ends of rays. Rhachilla winged. Glumes ± 2.5 mm long, not closely imbricate, ovate, scarcely keeled, tip obtuse or slightly mucronate, yellow-brown, distinctly nerved. Stamens 3. Style-branches 3. Nut ± ½ length of glume, obovate-oblong, trigonous, light brown.
N. Hamilton; Palmerston North. S. Canterbury - Belfast. Weed in gardens. (Warmer regions of Europe, Africa, Asia and N. and S. America)
First record: Healy and Edgar 1973: 25.
First collection: "Hamilton, weed in garden after flooding", G. S. Harris 3.3.1953 (CHR 83385).
C. esculentus is likely to be confused with C. rotundus but differs in the weak slender rhizomes with terminal tubers, leaves usually > stems, and yellowish to light brown shining glumes. It is a weedy plant, troublesome overseas in gardens and cultivated land, and, because of its similarity to C. rotundus, could be more widely distributed in N.Z. than is currently known.
A form of this sp., sometimes distinguished as var. sativus Boeck. (chufa, earth almond, tiger nut) is cultivated overseas for the edible tubers and for the tuber oil.
