Panicum konaense is a cespitose annual grass growing 10–60 cm tall. The stems are unbranched, either glabrous or papillose-pilose, with pilose nodes. The leaves are simple, alternate, and cauline. The blades are 5-18 cm long and 0.2-0.5 cm wide, flat, with ciliate and papillose-pilose surfaces. The lower surface is often sparsely pilose, though it can be puberulent or glabrous. The veins are parallel. The sheaths are papillose-pilose or rarely puberulent. The ligule is a ciliate membrane, 0.6-1.6 mm long, with the membrane being 0.1-0.3 mm long and the cilia 0.5-1.3 mm long. Stipules are absent. The flowers are arranged in panicles 4-16 cm long. The axis is scabrous and pilose, and the branches are spreading, pilose, and/or scabrous. Spikelets (pictured) are 1.5-3.9 mm long, acuminate, and pilose. The glumes are as long as the spikelet and acuminate, with the first glume about equaling or longer than the second. The first glume is pilose with hairs 1-3 mm long, primarily in the upper half or evenly distributed, and has 3-5 nerves. The second glume has just a few scattered hairs or is glabrous, with five nerves. The first floret is sterile, with the first lemma being shorter than the glumes, 5-7-nerved, and glabrous. The first palea is 1/4-1/3 as long as the first lemma. The second floret is blackish at maturity, 1.2-1.4 mm long and 0.5-0.6 mm wide, elliptic to lanceolate-elliptic, glossy, and smooth. Anthers are 0.5-0.8 mm long. The fruit is a caryopsis. It occurs in dry, open habitats between 10–930 meters.