Argyroxiphium kauense is an erect, single-stemmed or sparingly branched rosette shrub characterized by its woody vegetative stems that can be 0.3 to 7 decimeters long, with flowering stems extending from 7 to 25 decimeters. The leaves are silver to gray, presenting a dull appearance when dry, and are very narrowly sword-shaped, broadest below the middle. These leaves are very shallowly 3-angled to rhombic in cross-section, typically measuring 20 to 40 cm in length and 0.3 to 0.7 cm wide in the middle, with an obscure venation and densely silky surface. However, the hairs do not entirely cover the leaf surface. The flowers are notable for their large numbers, with about 100 to 350 heads found in simple, narrowly elliptic racemose or very rarely simple, paniculate inflorescences that usually span 70 to 220 cm in length and 12 to 29 cm in width. A sharply ridged rachis characterizes the inflorescences due to decurrent peduncles and a broadly convex receptacle, typically 4 to 7 mm in diameter. The false involucral cup is made up of 22 to 42 receptacular bracts, each 10 to 15 mm long, with some heads bearing 1 to 3 additional bracts among the disk florets. The ray florets, usually 3 to 11 per head, have colors ranging from white or yellow to wine-red and are usually 3-lobed. The disk florets, usually 50 to 200 per head, have whitish or yellow corollas at the base and apically tinged wine-red. The pappus of ray florets is reduced to a minute coroniform rim, while that of the disk achenes consists of 3 to 9 unequal scales up to 3 mm long. The fruits are achenes, usually somewhat bowed, with peripheral ones being arcuate and subapically very slightly geniculate, measuring 9.5 to 12 mm long (including the pappus). Argyroxiphium kauense is endemic to the south slopes of Mauna Loa on the island of Hawaii. It occurs primarily in moist forest openings or bogs between 1,600 to 2,320 m elevation, although plants also occur on well-drained substrates and in relatively dry sites.