Common names: mānā, `āhewa (O'ahu) (P. & E.), 'iwa puakea (Maui) (puakea, pale colored: "pale-colored 'iwa")

Endemic 

Latin irregularis, asymmetrical, suggesting an irregular cutting of the frond. However, the fronds are quite regular. One Latin use as an adjective, "divisible into equal halves along one plane only," would be appropriate here.

Plants medium-sized to large, terrestrial. Rhizomes decumbent. Fronds 60-100(-150) cm long. Stipes 1/2 or more frond length, straw-colored, glossy, glabrous except at very base. Blades regularly 1-pinnate-pinnatifid to 2-pinnate-pinnatifid, bright green, ovate or ovate-triangular, chartaceous, pinnae cut to winged rachises, tips pinnatifid; rachises winged nearly to basal pinna pairs, or often only to space between first or second pinna pairs. Pinnae 8-12 pairs, cut to winged rachis, lobes and irregular projections present on most pinnae (absent on the most distal pinnae), numerous and regularly arranged, well separated, long, pectinate, obliquely pointing toward pinna tips. Ultimate segments wide, cut only to winged costae. Coenosori long on pinna lobes and wings.

Occasionally common in localized sites in dry to mesic forests, 450-1,920 m, all major islands.

Pteris irregularis may be distinguished from P. hillebrandii by its more regularly arranged and usually comblike projections from the pinnae, and rachises winged from the top down to the space between the first and second pinna pairs.