STEM: erect, decumbent or spreading, branching near base, 0.6-3 m tall or more, up to 4.5 cm diam., forming extensive shoot system in larger plants; adventitious roots numerous, spreading widely in all directions, light rusty brown and smooth when young, soon becoming corky, rugose and eventually silvery-grey with age, 0.5-1.3 cm diam., internodes 0.5-1 mm long; prophyll scars 0.5-7 mm long, becoming pale silvery grey almost immediately after prophyll abscission, paler than true internodes; intravaginal squamules minute, 0.5-1 mm long, 0.4-0.8 mm broad, triangular or dentate or erose, only visible on newly exposed internodes, not persistent; foliage leaf scars 1-2 cm long, 2 5-3 cm wide, transverse-ovate-elliptic, pale grey. LEAF: prophyll about 16 cm long, 3.7 cm diam. at base; petiole (20-)36-44 (-58) cm long, 0.7 cm diam. at apex, sulcate adaxially with sharply angled margins, sometimes convex or flattened, rounded abaxially, light somewhat glaucous green, sheath (1-)2.2 -9 cm long; leaf blade pinnatifid, ± pendent from suberect to spreading petioles, broadly cordiform-sagittate in outline, overall length (32-)35-50 cm, overall width (23-)31-38 cm, upper surface dark green and usually strongly bluish-glaucous, lower surface paler, dull and less strongly glaucous; anterior division (20-)21.5-26.5 cm long, 30-38 cm wide, apical lobe subtriangular, usually oblique, acute to obtuse, cuspidate, primary lateral lobes 3-4(-5) per side, basal primary lateral lobes (3.5-)5-13 cm long, 3.5-6.3(-7.5) cm wide, becoming shorter towards apex of division, usually oblong, sometimes triangular or oblanceolate, rarely short and broadly triangular, with obtuse, rounded, or ± emarginate tips, rarely subtruncate or deeply notched, lobe margins entire, occasionally repand, main sinuses penetrating progressively less deeply towards base of division, primary lateral veins 3-4(-5) per side, arising at an angle of 20-90(-100°) to midrib, yellowish green on upper surface, cream yellow on lower surface; posterior divisions 11-20 cm long, 0.3-0.48 x overall blade length, (11 -)12.5 - 18 cm wide, denuded proximally on basiscopic side for (2.5 -)2.8-4.5 cm, primary acroscopic lobes 1 -2(-3), primary basiscopic lobes (1-)2-3, normally weak, short. INFLORESCENCE: peduncle 6-8.5 cm long, 2.1-2.4 cm diam. at apex, dull glaucous green; spathe 9-16 cm long, 3.2-4. cm diam, in middle, decurrent for 1-3.3 cm, outer surface dull, pale to mid-green, glaucous, margins whitish, inner surface ± glossy, yellowish-white; spadix 10.5-14.3 cm long overall, fertile male zone 3.5-4.7 cm long, 1.5-2 .2 cm diam., cream to white, sterile male zone 4-6 cm long, 1.8-2.6 cm diam., thicker and longer than male zone, cream to white, female zone 1.5-3.2 cm long, 1.4-2.3 cm diam., tapering upwards. FLOWERS: stamens 4.5-5.2 mm long, 0.5-0.9 mm diam. at apex; staminodes 5.3-7.6 mm long, 0.8-2 mm diam. at apex, prismatic and truncate towards apex of zone, terete and rounded apically towards base of zone; gynoecium 3.5-5.7 mm long, ovary 1.6-2.7 mm diam., cylindric, locules 6-11, ovules 2-4 per locule, inserted on locule axis one above the other from base to above middle, evenly spread,style body slightly narrower than ovary or style crown, axial region around stylar canals densely filled with raphide cells, compitum strongly ridged, not penetrating ovary, style crown deeply lobed, style lobes ± erect, densely tanniniferous, central dome lacking or very weakly developed, stigma 2.2-2.9(-3.5) mm diam., ± lacking on dorsal side of style lobes, contiguous with adjacent stigmas, translucent pale yellow at anthesis, tannin hairs lacking. INFRUCTESCENCE: berry many-seeded, 1 cm long, 0.5-0.6 cm diam., cylindric; seed 2.5-4.5 mm long, 1.4-2.4 mm diam., oblong-ovoid, sometimes galled, testa sarcotestate surrounding inner body and containing oily droplets, raphide cells numerous in inner integument.
The local inhabitants of this former diamond-mining district use the roots, when hollowed out, for storing diamonds. Only a single plant was known in the neighbourhood and possibly the São Inácio plant represents a last remnant of a more extensive range during earlier more mesic conditions (see section 10).