Anthurium holm-nielsenii Croat

Epiphytic, occasionally terrestrial; stem 1.5–3.5 cm diam.; leaf scars 1.5–1.7 cm high, 2.2–2.5 cm wide; roots dense, descending, pale, moderately elongate; cataphylls coriaceous, lanceolate, 17–25 cm long, narrowly acute at apex, drying light brown to tan, persisting as linear fibers at the apex of the stem. Leaves spreading; petioles (18)24–47 cm long, 7–12 mm diam., sharply D-shaped and slightly thicker than broad, broadly convex to weakly ribbed medially adaxially, the margins sharply raised to winged, rounded abaxially; geniculum thicker and paler than petiole, becoming fissured transversely with age, 1–3 cm long; blades coriaceous, oblong-oblanceolate to oblanceolate-elliptic, long-acuminate at apex, narrowly acute at base, (50)76–98.5 cm long, (11)13–27 cm wide, the margins broadly undulate; upper surface matte to semiglossy, dark green, lower surface semiglossy to glossy, slightly paler; both surfaces drying concolorous, green to yellowish; midrib above prominently convex and paler than surface, below thicker than broad at base of the blade, becoming prominently convex toward the apex and paler than surface; primary lateral veins numerous, to more than 20 per side, departing midrib at 45–60 degree angle, more or less straight to the collective vein, moderately obscure, weakly sunken to raised above, darker than surface and weakly raised below; interprimary veins almost as conspicuous as primary lateral veins, numerous; tertiary veins obscure, raised on drying; collective vein arising from near the base, weakly sunken above, equally as prominent as primary lateral veins on drying and when fresh, 5–25 mm from margin. Inflorescences spreading; peduncle 24–64 cm long, 3–6 mm diam., 1.4–2(3.4) times as long as petiole, green tinged with purple, terete; spathe erect to spreading, subcoriaceous, green, sometimes heavily tinged purplish or red, broadly lanceolate to oblong-lanceolate, 6–17.5 cm long, 1.5–2.7 cm wide, broadest near the base, acuminate at apex (the acumen inrolled), acute to obtuse at base; stipe 1–2.2 cm long in front, 1–2 mm long in back; spadix green (B & K yellow-green 5/5), also reported as brownish, long-tapered, subsessile, straight to prominently curved, 9–20.5 cm long, 6–9 mm diam. near base, 3–4 mm diam. near apex; flowers square, 2.3–2.7 mm in both directions, the sides smoothly to jaggedly sigmoid; 7–8 flowers visible in principal spiral, 4–5 in alternate spiral; tepals matte, densely and minutely papillate; lateral tepals 1.2–1.4 mm wide, the inner margins straight, the outer margins 2–4-sided; pistils slightly raised, minutely papillate, green; stigma linear, 0.4–0.5 mm long, the laterals preceding the alternates by 8–9 spirals, the 3rd stamen preceding the 4th by 1–3 spirals; filaments fleshy, translucent, somewhat flattened, 7–0.8 mm wide; anthers dark yellow, 0.6–0.8 mm long, 0.6–0.9 mm wide; thecae oblong-ovoid, not divaricate; pollen orange. Infructescence with the spathe persisting; spadix 16.8–31 cm long, 1.4–2.3 cm diam.; berries orange, oblong-ovoid, slightly beaked, 6.5–7.4 mm long, 4–4.5 mm diam.; pericarp somewhat thickened, with linear raphide cells; mesocarp transparent, gelatinous; seeds 1–2 per berry, yellowish brown when dried, oblong, sometimes ovoid, 3.5–4.7 mm long, 2.3–2.7 mm diam., 1.6–2 mm thick, with a gelatinous, with a sticky appendage at both ends.

A member of series Multinervii, Anthurium holmnielsenii is known only from Ecuador in the provinces of Los Ríos, Imbabura, Pichincha and Cotopaxi at 250 to 1,500 m in tropical moist and premontane wet forest, where it grows either terrestrially or as an epiphyte. This species is distinguished by its concolorous, green﷓drying leaf blades with numerous primary lateral veins and a collective vein arising from near the base, its sharply D﷓shaped petioles, its long﷓tapered, green spadix and its orange berries. Anthurium holmnielsenii is closely allied to A. acutissimum, and differs in having petioles with sharply raised margins and spreading﷓pendent to more or less erect leaves with broader blades (3.3--6.5(7) vs. (6.7)7.5--10(11) times longer than broad).

Anthurium holm-nielsenii is a species of plant in the family Araceae. It is endemic to Ecuador. Its natural habitat is subtropical or tropical moist montane forests. It is threatened by habitat loss.