Anthurium atropurpureum var. arenicola (Araceae)
Terrestrial or epiphytic; stem to 30 cm long, 1-3.5 cm diam.; leaf scars obscured by root mass and cataphylls, 1.5-2 cm wide; roots numerous, dense, mostly descending, uppermost ascending, gray or green, smooth to densely pubescent, elongate, blunt, 5-30 cm long, 3-6 mm diam.; cataphylls moderately thin to subcoriaceous, bluntly 1-ribbed near the apex, 5-12 cm long, narrowly acute to acute at apex, tinged with red, drying tan (B & K yellow-red 7/2.5), persisting with apex remaining intact, eventually deciduous. LEAVES erect-spreading, rosulate or scattered along stem; petioles 4-63 cm long, 3-12 mm diam., erect, slightly thicker than broad to D-shaped, shallowly sulcate adaxially, sometimes obtusely V-sulcate, the margins moderately sharp, rounded abaxially, the surface pale-speckled, tinged with red near the base; geniculum markedly thicker than petiole, slightly paler, 1-3 cm long; blades coriaceous to subcoriaceous, narrowly to broadly oblanceolate, less often elliptic, acute to abruptly acuminate, sometimes gradually acuminate at apex (the acumen to 4 cm long, inrolled), long-attenuate or rarely acute at base, sometimes making geniculum seem remote, occasionally acute to obtuse, (16)45-80(100) cm long, 8-25(41) cm wide, broadest at or above the middle, the margins undulate; upper surface weakly glossy to glossy, medium green, lower surface semiglossy to matte, only slightly paler and mostly eglandular, rarely weakly pustulate, both surfaces drying green and paler below, matte; midrib flat at base, becoming acute-raised to convexly raised toward the apex above, higher than broad to prominently acute-raised below; primary lateral veins 5-13 per side, departing midrib at (30)40-65(70)° angle, usually weakly arcuate-ascending to the collective vein, sunken to convexly raised above, prominently and convexly raised below, paler than surface; interprimary veins etched above, weakly raised below, prominulous when dried; tertiary veins conspicuously etched above, flat to prominulous below; collective vein arising from about the middle or in the upper ? of blade, sometimes arising in lower 1/2,sunken above, raised below, flat above when dried; antimarginal vein visible on live plant, running close to margin from the base; 1st collective vein 9-12 mm from margin. INFLORESCENCES erect to spreading, shorter than or equalling leaves (rarely longer than leaves); peduncle (12)20-73 cm long, 2-8 mm diam., 1-4 x as long as petiole, green to green heavily tinged with purple, terete; spathe spreading to reflexed and recurled or twisted, withering at anthesis, subcoriaceous, matte on both surfaces, pale to medium green, heavily tinged with red-violet, sometimes maroon to purple, lanceolate to narrowly lanceolate, 4-22 cm long, 0.6-2.5 cm wide, broadest near the base, inserted at 45° angle on peduncle, long-acuminate at apex, broadly acute, decurrent to 2 cm at base, the margins meeting at ca. 45° angle; spadix green (B & K yellow 5/7.5) heavily tinged with violet-purple, to dark purple or maroon, cylindroid to tapered, sessile or stipitate to 16 mm, erect, 4-26 cm long, 3-8 mm diam. near base, 3-5 mm diam. near apex, broadest at the base; flowers square to rhombic, 1.5-2.6 mm long, 1- 2.5 mm wide, the sides straight to sigmoid, 5-8 flowers visible in principal spiral, 5- 10 in alternate spiral; tepals matte, weakly to densely and minutely papillate, muricate, lateral tepals (0.5)0.8-1 mm wide, the inner margins pale, thin, pinkish, straight to weakly convex, the outer margins 2-3-sided; pistils weakly emergent before stamens emerge, ± square, green, developing a maroon tinge, sometimes somewhat papillate; stigma ellipsoid, 0.2-0.6 mm long, depressed medially, lightly or densely papillate, droplets appearing 7-11 days before anthesis; stamens emerging in a regular sequence from the base, lateral stamens followed by alternates in rapid succession (7 days), the laterals preceding the alternates by 5-1 0 spirals, held over and obscuring pistil, 3rd barely preceding 4th; anthers yellow, 0.2-0.6 mm long, 0.8 mm wide, held at edge of the pistil, only partially exserted; thecae oblong-ellipsoid, 0.2-0.4 mm wide, not divaricate or only slightly divaricate; pollen yellow fading to cream, faintly sweet- or yeasty-scented. INFRUCTESCENCE spreading to pendent; spathe withered or absent; spadix 14-35 cm long, 1-2.5 cm diam., bearing berries in the basal portion only, the stipe to 1.5 cm long.; berries white to greenish white basally, violet-purple in apical 1/2 (B & K purple 2/7.5), subglobose, rounded at apex, 6-8 mm long, 4-6 mm diam.; pericarp somewhat thickened, with raphide cells; mesocarp with raphides, thickly gelatinous; seeds 1-2 per berry, pale green becoming purple (B & K purple 3/2.5), oblong-ellipsoid, 3-6 mm long, 2-3 mm diam., 1.4-1.6 mm thick, with a basal mucilaginous appendage at radicle end.
Anthurium atropurpureum var. arenicola ranges from southern Colombia (Putumayo and Amazonas) to western Brazil (Amazonas, Acre, and western Rondônia), Ecuador (Morona Santiago, Napo, and Pastaza), Peru (Amazonas, Loreto, and Madre de Dios), and Bolivia (La Paz),
Principally found in tropical moist forest life zones, in mature forest on white sand soils (hence the name)