Philodendron avenium Grayum & Croat

Hemiepiphytic vine; internodes 3.5-6 cm long, drying 4-5 mm diam., coarsely and irregularly ridged longitudinally, pale yellow-brown, semiglossy, the epidermis otherwise smooth. LEAVES: Petioles 7-8 × 7.4-7.5 cm, sheathed to within 8 mm from base of blade; sheath 5.5-7.4 cm × 5-7 mm on each side, held erect, along with the shaft of the petiole finely ribbed on drying, yellowish brown; free part of petiole sharply and narrowly sulcate on drying; blades oblong-elliptic, 21.2-21.8 × 7.5 cm, 2.6-2.9 times longer than wide, 3.1 times longer than petioles, weakly short-acuminate at apex, narrowly rounded at base, drying gray and matte above, paler and yellowish gray and weakly glossy below; midrib scarcely visible, weakly raised and concolorous above, convex, light yellow brown and finely ridged below; primary lateral veins not at all apparent; minor veins arising at ca. 35° angle, narrowly and weakly raised above, scarcely raised below, both surfaces finely granular throughout including on the minor veins. INFLORESCENCE solitary; peduncle 5.5 cm long, drying 3.5 mm wide, coarsely ridged and densely pale-speckled; spathe 7.5-10 × 1.8 cm, medium green outside, drying matte, paler green within, drying yellow-brown with prominently raised purplish resin canals extending throughout much of the spathe (to within 2 cm from tip of spathe); spadix stipitate 3 mm long on back side, 8.7 cm long; pistillate spadix 2.5 × 1.0 cm, weakly tapered toward the base; staminate spadix drying 6.4 cm long, sterile portion 1 × 1.1 cm; fertile staminate portion narrowly tapered toward apex, 6 mm diam.; pistils narrowly tapered to apex, drying 0.5 mm diam.; style with a broad thin wafer-like apron 1-1.2 mm wide; stigma donut-shaped, 0.8 mm diam.