Helodeaster maviensis is a rhizomatous perennial herb, usually branched at the base. The stems are unbranched or branched at the base, with each branch having 1-5 lateral branches. Older stems become decumbent and usually produce adventitious roots. The leaves form a basal rosette or are distributed up to 16 cm along the ascending stem. They are spatulate, oblong, obovate to oblanceolate, measuring (1.5-)3-6.9 cm long and 0.4-1.3(-1.9) cm wide. The leaves are sessile and clasp the stem, with 1-13 bracts per scape that usually become progressively larger and more leaf-like toward the base. They are sparsely glandular-pubescent on the margins and veins, with the upper surface sometimes sparsely to moderately villous and the lower surface usually glabrous. The margins are coarsely serrate or sometimes dentate in the upper half, usually with five opposite pairs and one apical tooth, the teeth up to 2 mm long, sometimes purple at the tip. The heads are solitary, 8-19 mm in diameter, radiate, on scapes 3-30(-50) cm long, sparsely to moderately glandular, pubescent, and villous, especially at the base of the head, becoming glabrate with age. The involucral bracts are usually tinged purple at the apex, 4.5-8 mm long, sparsely to moderately glandular-pubescent, especially along the margins, which are fringed. Ray florets are conspicuous and pistillate, with rays that are white or green, sometimes tinged lavender or reddish purple, entire, 2-lobed, or merely notched at the apex, very rarely 3-lobed, (1.4-)2.5-3.9 mm long, sometimes with a few long hairs, and a purplish pistil. Disk florets are perfect, with yellow, peach-orange to purple corollas, 4-5-lobed, rarely 3-lobed, (2.4-)2.8-3.5 mm long, and purple filaments and anthers. The fruit is a simple, dry achene that is compressed, tapering to the apex, and usually conspicuously beaked, occasionally scarcely beaked, with a conspicuous cartilaginous ring at maturity, 2-4.5 mm long, with scattered, subsessile, globose glands at the apex and sometimes near the base. It occurs in bogs and montane wet forests between 915-1980 meters.