Leaves simple, not lobed; not dark glandular-punctate, not cordate or subcordate at base.
la. Plants with the stem elongate with long intemodes (1 cm or more), the leaves usually dispersed throughout much of the length of the stem.
2a. Spathe decurrent on the peduncle (0.5-)1-1.5 cm; berries yellow to orange or white.
3a. Internodes short, usually less than 1 cm long (rarely to 2 cm long); blades mostly more than 3 times longer than broad; primary lateral veins 13-20 pairs, mostly drying obscure..........A. pittieri Engl. var. pittieri
3b. Intemodes elongate, 1-8.5 cm long (mostly 1-2.5 cm); blades mostly less than 3 times longer than broad; primary lateral veins mostly 7-9 pairs, drying moderately conspicuous..........A. pittieri var. morii Croat
2b. Spathe essentially not decurrent; berries green, yellow, orange, or bright red to red-violet.
4a. Stems with 2 or more successive, abbreviated intemodes, 8-3 3 cm long; leaves drying brownish green or olive green; berries bright red or red-violet; below 1,000 m..........A. interruptum Sodiro
4b. Stems with intemodes nearly uniform in length, decreasing slightly toward the apex of the stem; leaves drying dark brown to blackish or pale green; berries green, red, or orange; usually above 1,200 m, rarely below 1,000 m (except A. coclense 500-1,000 m).
5a. Blades drying black or blue-black, dark brown on the upper surface, medium brown on the lower surface; 1,500-2,600 m; leaves fleshly when fresh with veins obscure..........A. carnosum Croat & Baker
5b. Blades drying dark green to pale green above, pale yellow-green or occasionally brownish beneath; 500-2,300 m; leaves thickly chartaceous with veins prominent below.
6a. Spadix slender and narrowly tapered to apex, more than 7 cm long at anthesis; berries red, early emergent, oblong ..........A. testaceum Croat & Baker
6b. Spadix blunt and scarcely tapered to apex, usually less than 7 cm long at anthesis berries yellow-green or red, not early emergent, more or less globose or ovoid.
7a. Leaf blades mostly more than 10 cm wide; peduncles usually less than one-half as long as petioles; berries red..........A. coclense Croat
7b. Leaf blades mostly less than 10 cm wide; peduncles usually more than one-half as long as petiole; berries yellow-green.
8a. Petioles mostly more than 15 cm long; leaf base acute to rounded; stipe 1-5 mm long; leaves usually clustered at the ends of branches (intemodes short) with the more elongate lower nodes usually leafless..........A. pallens Schott
8b. Petioles mostly less than 15 cm long; leaf base often truncate or subcordate: stipe 2-10 mm long; leaves evenly distributed along the branches and per-sistent, the apical intemodes not usually shortened..........A. microspadix Schott
1b. Plants erect or pendent with a generally short stem with short intemodes, the leaves usually clustered near the apex of the stem, often with a rosulate habit.
9a. Leaf blades with the primary lateral veins in at least the lower one-fourth of blade running to the margin, not forming a collective vein in the basal one-fourth.
l0a. Spadix purplish at anthesis (lavender to violet purple).
11a. Peduncle usually shorter than petiole, never more than 2 times longer than petiole, less than twice as long as spadix; spadix lavender to violet purple at anthesis; berries red.
12a. Petioles usually sharply quadrangular; the spadix dark violet purple; Atlantic coast to the Continental Divide in wetter parts of tropical moist forest and pre-montane wet forest..........A. purpureospathum Croat
12b. Petioles subterete to obscurely quadrangular, usually rounded adaxially; the spadix whitish to lavender at anthesis; Pacific coast in tropical dry forest and drier parts of tropical wet forest..........A. cubense Engl.
11b. Peduncle mostly 2 or more times longer than petiole, more than twice as long as spadix: spadix violet purple at anthesis; berries orange, red, or purple.
13a. Cataphylls cucullate (hooded), fist-shaped before opening (the new leaf unrolling like a fem frond); inflorescence frequently pendent at anthesis; spadix pale lavender, weakly glaucous; spathe narrowly lanceolate, almost as long as the spadu at anthesis..........A. salviniae Hemsl
13b. Cataphylls lanceolate (the new leaf not rolled longitudinally); inflorescences erecl at anthesis; spadix usually dark violet purple, not glaucous; spathe much shorte-than spadix or if longer then more or less oblong to narrowly ovate or oblong-lanceolate.
14a. Spathe narrowly ovate to ovate-lanceolate, 2-11 cm wide, usually dark violet purple, erect and hooding the spadix..........A. luteynii Croat
14b. Spathe linear-lanceolate to oblong-ovate or oblong-elliptic, usually less than 2 cm wide, usually green.
15a. Pistils early emergent and acute, much longer than the stamens at anthesis; the berries white at base, reddish to purplish at apex..........A. consobrinum Schott
15b. Pistils not early emergent, rounded at apex, usually shorter than the stamens at anthesis; the berries purple or red.
16a. Pollen yellow, fading white; berries purple; spadix sharply ta-pered, spathe usually narrowly lanceolate, soon withering..........A.fendleri Schott
16b. Pollen lavender; berries red; spadix scarcely tapered to a blunt apex, spathe more or less oblong, persistent intact..........A. concolor K. Krause
l0b. Spadix green or yellow-white at anthesis.
17a. Spadix clavate, less than 6 cm long, yellowish white; spathe cucullate, hooding spadix..........A. cuneatissimum (Engl.) Croat
17b. Spadix broadest at base, long-tapered to apex, more than 6 cm long, green; spathe not cucullale.
18a. Stems lacking markedly shortened internodes with numerous, closely aggregated roots; blades thin, lanceolate to narrowly elliptic, arching, lacking rosulate habit; leaf vernation supervolute...........A. cerropirrense Croat
18b. Stems markedly shortened with short internodes and numerous usually closely aggregated roots; blades moderately thick, oblanceolate, oblong-lanceolate with a rosulate habit or strap-shaped and many times longer than broad; leaf vernation involute.
19a. Long pendent epiphyte, usually suspended by few roots; petioles rounded abaxially, not ribbed; blades at least 3 times longer than broad; spathe usually purple, twisted or contorted at anthesis; berries orange; pistil early exserted..........A. pseudospectabile Croat
19b. Erect, bird's nest epiphytes or terrestrial; petioles quadrangular or ribbed abaxially; blades less than 3 times longer than broad; spathe green, not twisted; berries various.
20a. Plants usually terrestrial; blades prominently attenuate toward base, gradually tapering onto petioles; berries yellow-green; roots not in a massive cluster with many directed upwards..........A. acutifolium Engl.
20b. Plants epiphytic; blades narrowing toward base but ending abruptly on petiole; berries white; roots in a massive cluster with many di-rected upward..........A. fatoense K. Krause
9b. Blades with a collective vein arising in the basal one-fourth.
2la. Spadix purplish at anthesis.
22a. Spadix with 2-3 flowers visible in each spiral from any angle; cataphylls persisting intact; primary lateral veins scarcely distinguishable from interprimary veins; berries red..........A. gracile (Rudge) Lindl.
22b. Spadix with 4 or more flowers visible in each spiral; cataphylls weathering into fibers; primary lateral veins much more prominent than the interprimaries; berries orange or red (not known m A. cerropirrense).
23a. Primary lateral veins and collective vein prominently sunken above, prominently raised beneath.
24a. Spadix 2-6 cm long at anthesis, on a short stipe; the spathe frequently ovate, usually more or less hooding the spadix..........A. protensum Schott ssp. arcuatum Croat
24b. Spadix usually more than 10 cm long, sessile; the spathe usually oblong-lanceolate, often becoming coiled..........A. seibertii Croat & Baker
23b. Primary lateral veins and collective vein not prominently sunken above, slightly raised beneath.
25a. Leaf blades more than 6 times longer than broad, usually broadest near middle..........A. cerropirrense Croat
25b. Leaf blades less than 5 times longer than broad, usually broader at the base than at the middle.
26a. Leaf blades thin, often drying with reddish discolorations along the major veins; the spadix scarcely or not at all tapered toward the apex with 4-5 flowers visible in the principal spiral from any angle..........A. cuspidatum Mast.
26b. Leaf blades coriaceous, not drying with reddish discolorations; the spadix prominently tapered with 7-9 flowers visible in the principal spiral from any angle..........A. validifolium K.. Krause
21b. Spadix green, yellow, or white, not purplish. 27a. Spadix sessile or nearly so.
28a. Plant pendent; leaves usually more than 1 m long; spathe purplish..........A. pseudospectabile Croat
28b. Plants erect; leaves usually less than 70 cm long; spathe green.
29a. Spadix clavate; petiole sharply 3-4-sided..........A. spathiphyllum N. E. Brown
29b. Spadix broadest at base, slightly to prominently tapered toward apex: petiole terete.
30a. Spadix narrowly and sharply tapered to apex, with 5-10 flowers vis-ible in each spiral..........A. angustispadix Croat & Bakerr
30b. Spadix scarcely narrowing toward apex.
31 a. Leaf blades less than 7 cm wide; spadix with 2-4 flowers visible in each spiral; usually above 1,000 m..........A. pallens Schott
31 b. Blades more than 10 cm wide; spadix with 7-10 flowers in each spiral; usually below 1,100 m..........A. coclense Croat.
27b. Spadix conspicuously stipitate.
32a. Petioles less than one-third as long as blades.
33a. Spadix at anthesis less than 2 cm long.
34a. Leaf blades broadest at middle; roots flattened, ribbon-like..........A. platyrhizum Croat
34b. Leaf blades broadest above the middle; roots not flattened and ribboo-like.
35a. Spathe lanceolate, long-decurrent onto peduncle; spadix much longer than broad at anthesis..........A. correae Croat1
35b. Spathe ovate, scarcely decurrent onto peduncle; spadix nearly globular..........A. llanoense Croat
33b. Spadix at anthesis more than 2 cm long.
36a. Leaf blades conspicuously broadest above the middle; berries purple.
37a. Spathe markedly decurrent onto peduncle; blades usually drying black; spadix at anthesis less than 3 cm long..........A. correae Croat
37b. Spathe scarcely decurrent; blades usually drying green; spadix usually more than 3 cm long at anthesis.
38a. Spadix at anthesis yellow...........A. wedelianum Croat ssp. wedelianum
38b. Spadix at anthesis green..........A. wedelianum ssp. viridispadix Croat
36b. Leaf blades not conspicuously broadest above the middle; berries orange or purple.
39a. Spathe usually tinged purple, longer than spadix even in fruit-hooding spadix; spadix usually lavender, rarely greenish; berries orange; blades drying green; primary lateral veins and collective vein prominently raised beneath..........A. protensum Schott ssp. arcuatum Croat
39b. Spathe green, soon shorter than spadix, reflexed; spadix green: berries purple or white or orange; blades usually drying dark.
40a. Blades subcoriaceous, drying with reticulate veins obscure; spathe conspicuously decurrent; pistils early emer-gent (before stigmas are receptive), pointed at apex; sta-mens much shorter than pistil at anthesis; berries orange to white..........A. pittieri Engl. var. pittieri
40b. Blades moderately thin (at least when dry) drying with reticulate veins prominent; spathe scarcely or not at all decurrent; pistils not early emergent, stamens longer than the pistil at anthesis; berries purple, sometimes white at base..........A. michelii Guillaumin
32b. Petioles more than one-third as long as blades.
4la. Spathe purple, nearly as broad as long; spadix cream, less than 3 cm long..........A. hammelii Croat
41b. Spathe green, sometimes tinged purple, at least twice as long as broad; spadix green.
42a. Spadix less than 1.5 cm long, half as broad; roots flattened, ribbon-like..........A. platyrhizum Croat
42b. Spadix more than 2 cm long, more than twice as long as broad: roots not flattened.
43a. Spathe conspicuously decurrent; blades subcoriaceous, drying with the primary lateral veins scarcely raised, scarcely more conspicuous than the intcrprimary veins; berries white, yellow to orange; pistils early emergent, much longer than stamens at anthesis..........A. pittieri Engl. var. pittieri
43b. Spathe scarcely or not decurrent; blades moderately thin, drying with the primary lateral veins usually prominent, usually more conspicuous than the interprimaries; pistils not early emergent, not longer than stamens at anthesis; berries red, orange, white, or purple (not known in A. cerropirrense).
44a. Peduncles usually less than one-half as long as the petioles; blades usually rounded at base..........A. coclense Croat
44b. Peduncles usually about as long as or longer than the petioles; blades usually acute to obtuse at the base.
45a. Blades much paler beneath when fresh, frequently drying blackened, the midrib and petiole acute abaxially; berries purple..........A. michelii Guillaumin
45b. Blades only slightly paler beneath, usually drying green, the midrib and petiole rounded abaxially.
46a. Spathe ovate to ovate-lanceolate, frequently purplish, usually longer than spadix even in fruit; petiole sometimes 3-ribbed abaxially; berries orange..........A. protensum Schott ssp. arcuatum Croat
46b. Spathe lanceolate to oblong-lanceolate, usu-ally green (sometimes purple in A. cerropirrense) soon shorter than spadix; petioles terete; berries greenish or red (not known in A. cerropirrense).
47a. Spadix at anthesis less than 4.5 cm long, scarcely tapered to apex, stubby; ber-ries yellowish green..........A. pallens Schott
47b. Spadix more than 5 cm long at anthe-sis, either very long and slender or con-spicuously tapered to apex; berries red or purple.
48a. Spadix with 4-7 flowers visible per spiral; tepals flat, not clearly distinguished from one another by a sunken line, the internodes very short; berries purple at maturity; Darien Province on Serrania de Pirre..........A. cerropirrense Croat
48b. Spadix with usually about 3 flowers visible per spiral; tepals prominently elevated, clearly distinguished from one another by a sunken line between the flowers; the internodes visibly elongated except at the apex; ber-ries red at maturity; Chiriquí Province and adjacent Costa Rica..........A. testaceum Croat & Baker