Leaves simple, sometimes 3-lobed (but not to the base); the margins constricted near the base of the anterior lobe.
la. Posterior lobes of the blade usually rcflcxed or spreading laterally at 90ˇ angle.
2a. Posterior lobes usually markedly curved backward at the base, directed slightly inward, generally not broader toward the apex; blades coriaceous, the margins markedly undulate..........A. brownii Mast.
2b. Posterior lobes usually not curved back-ward and inward at the base, generally broader toward the apex; blades thin to coriaceous, the margins straight or nearly so, not markedly undulate.
3a. Blades drying yellow-green, comparatively thin, the dried lower surface markedly glossy; posterior rib naked only near the base; the basal veins then fanning out in both directions from the posterior rib; berries pale green..........A. panduriforme Schott
3b. Blades drying brownish, comparatively coriaceous to subcoriaceous; the dried lower surface matte; posterior rib naked throughout most of its length, continuous along the edge of the blade with the posterior ribs all directed away from the lower edge; berries red..........A. anguslilobum Croat
1 b. Posterior lobes of blades usually arched prominently toward the apex.
4a. Plants terrestrial, well-rooted, the lower blade surface matte; spadix green..........A. impolitum Croat
4b. Plants epiphytic; the lower blade surfaces semiglossy to glossy (at least on live plants); spadix white, yellow, or reddish (rarely green just before anthesis on A. tilaranense).
5a. Cataphylls persisting intact; spadix greenish white to white, less than 10 cm long..........A. tilaranense Standl.
5b. Cataphylls weathering to persistent coarse fibers; spadix greenish, yellow, or reddish violet, more than 13 cm long.
6a. Spadix bright yellow; posterior lobes of larger leaves usually broadly rounded at apex, usually less than 2 times longer than broad; usually less than 700 m, CoclŽ, Col—n, and Panama Provinces..........A. garagaranum Standl.
6b. Spadix green or reddish violet to magenta; posterior lobes narrowly rounded to bluntly acute, usually more than 2.5 times longer than broad.
7a. Spadix reddish violet to magenta; western Panama..........A. madisonianum Croat
7b. Spadix greenish; eastern Panama..........A. cineraceum Croat