Key for Peperomia Ruiz & Pav.

1Leaves opposite or in whorls of 1-7
1'Leaves alternate
2Leaf apex acute or somewhat acuminate
2'Leaf apex obtuse, rounded or emarginate
3Stem glabrous; leaves glabrous; spikes 10-16 cm long; fruit with apical stigma
3'Stem villous; leaves pubescent; spikes 2.5-15 cm long; fruit with subapical stigma
4Leaves opposite
4'Leaves in whorls of 1-7
5Stem minutely hirtellous; leaf margin not ciliate; peduncle without bracts
5'Stem minutely pubescent; leaf margin ciliate; peduncle 2-bracteate
6Stem glabrous
6'Stem variously pubescent
7Fruit slightly stipitate at maturity; stigma apical
7'Fruit (sub)basely attached, not stipitate; stigma apical on short, thick style, or fruit with small beak and subapical stigma, or fruit apex oblique with subapical stigma
8Rachis of spike pubescent; fruits sunken in rachis
8'Rachis of spike glabrous; fruits (sub)basely attached, not sunken
9Spikes to 15 cm long, terminal or axillary, often in groups of 2-5; leaf blade 0.2-0.6 mm wide, apex obtuse; fruit apex oblique with subapical stigma
9'Spikes 2-7 cm long, terminal and solitary; leaf blade 0.6-2.3 cm wide; apex rounded to emarginate; fruit with short, thick style and apical stigma
10Spikes in panicles
10'Spikes simple, solitary, 2-few together or bifurcate
11Leaves distinctly peltate
11'Leaves basely attached or slightly peltate
12Leaf apex rounded, blade with erect trichomes at upper surface; petiole attached centrally; fruit flat at apex
12'Leaf apex somewhat acute to acuminate, blade glabrous or minutely pubescent; petiole attached between base and leaf centre, 0.2-3 cm from base; fruit with slender beak
13Stem and leaf blade minutely pubescent; petiole 3-11(-16) cm long
13'Stem and leaf blade glabrous; petiole 1.5-6 cm long
14Leaf apex rounded or emarginate
14'Leaf apex acuminate, acute to obtuse
15Stem and leaf blade glabrous; blade 2-14 cm long; spikes 2-18 cm long
15'Stem and leaf blade crisp-pubescent or minutely hirtellous; blade less than 2 cm long; spikes to 2 cm long
16Petiole not grooved or winged; peduncle as long as or longer than spikes; spikes 2-5 cm long
16'Petiole grooved or winged; peduncle as long as or shorter than spikes; spikes to 18 cm long
17Leaf blade in vivo fleshy; floral bracts 5-7 mm in diam.; fruit subglobose
17'Leaf blade in vivo coriaceous; floral bracts 2-4 mm in diam.; fruit ellipsoid
18Leaf apex emarginate; stem glabrous, sparsely villous or minutely hirtellous
18'Leaf apex rounded; stem crisp-pubescent
19Stem minutely hirtellous; leaf blade 0.5-0.8 x 0.5-1 cm; fruit crowned with persistent, conic style, stigma mammiform; above 2000 m elev.
19'Stem glabrous or sparsely villous; leaf blade 0.15-0.6 cm in diam.; fruit with apical stigma, not mammiform; from sealevel up to 600 m elev.
20Leaf blade broadly elliptic to deltoid; peduncle nodose or with 1-2 (falling off early) bracts, often longer than flowering rachis; fruit ellipsoid
20'Leaf blade almost circular, broadly elliptic or elliptic; peduncle not nodose, without bracts, usually shorter than flowering rachis; fruit globose to ovoid
21Terrestrial herbs
21'Epiphytic or epilithic, occasionally terrestrial herbs
22Leaf blade broadly elliptic to deltoid, 1-3.7 cm long; spikes terminal, to 6 cm long
22'Leaf blade ovate, to 12 cm long; spikes axillary, to 17 cm long
23Leaf base truncate, cord(ul)ate or rounded; spikes 1-5 cm long
23'Leaf base cuneate, acute to obtuse; spikes 1.5-30 cm long
24Leaf blade 0.8-2.5 x 0.8-2.5 cm; spike axillary, 1-2.5 cm long, shorter than peduncle
24'Leaf blade 2-3 x 2.7-7 cm; spike terminal, 1.5-5 cm long, about as long as peduncle
25Older leaf blades 4-20 cm long; spikes 4-30 cm long
25'Older leaf blades less than 4 cm long; spikes 1.5-7 cm long
26Whole plant strongly glandular dotted (black when dried); petiole usually with 2 rows of hairs; peduncle glabrous
26'Plants at most somewhat glandular, not black-dotted when dried; no lines of hairs on petiole; peduncle glabrous or minutely puberulous
27Internodes of stem longitudinally ridged or winged; petiole deeply grooved, glabrous; fruits laterally attached, globose-ovoid
27'Internodes not winged nor ridged; petiole narrowly winged or not, glabrous or sparsely, minutely puberulent; fruits basely attached, cylindrical or ellipsoid
28Leaf blade narrowly elliptic to ovate, upper surface usually covered with waxy exudate forming star- or scale-like structures; spikes to 30 cm long; growing on ant’s nests
28'Leaf blade narrowly elliptic to obovate, upper surface not covered with waxy exudate; spikes to 18 cm long; not growing on ant's nest
29Leaf blade 1-3 cm wide, apex acuminate; fruits with short beak
29'Leaf blades 2.5-6 cm wide, apex at most acute; fruits tapering into a slender beak, which is slightly hooked at very tip
30Leaf blade 0.8-2.3 cm wide, often, or at least at veins, red below; spikes 5-7 cm long
30'Leaf blade less than 1 cm wide, green; spikes to 5.5 cm long
31Leaf blade villous, apex obtuse; veins obvious; fruit sessile
31'Leaf blade glabrous or shortly puberulous, apex obtuse and minutely emarginate with some hairs in the indentation; veins obsolete; fruit stipitate at maturity