Start PageKEY 3Morphology of vegetative structures

KEY 4:


[Note: None of the species in this group are naked along the sinus except P. brunneicaule, P. hederaceum, P. mexicanum, and sometimes weakly naked in P. coloradense, P. cotonense, P. sulcicaule, and P. wilburii var. longipedunculatum, P. wilburii var. wilburii, and P. zhuanum.


1. Internodes elongate, usually much longer than broad; plants usually vines or at least prominently scandent.

2. Blades with the posterior rib (coalesced basal veins) not naked (i.e. not running closely parallel to the margin of the sinus).  
3. Stems coarsely asperous, covered with branched scales or setose-pubescent.  
4. Blades ovate-triangular, subcoriaceous; posterior lobes slender, usually flaring; stems reddish brown, covered with trichome- like, frequently branched scales; berries pale yellow; style very short; occurring usually in wet habitats; Nicaragua to Panama and South America, 60-230 m.
P. brevispathum Schott

4. Blades ovate-cordate, thin; posterior lobes directed inward at maturity; stems greenish, covered with elongate setae; berries pale orange to red or reddish orange; usually occurring in dry habitats; Mexico to Panama, West Indies and South America, 0-1,500(2,500) m.
P. jacquinii Schott

3. Stems smooth, not covered with branched scales.

5. Petioles prominently flattened dorsiventrally with the lateral margins sometimes acute; Nicaragua to Ecuador, 0-1,250 m.
P. platypetiolatum Madison

5. Petioles terete to subterete, not prominently flattened laterally.

6. Peduncles usually much shorter than the spathe, usually short and stout, usually less than 7 cm long at anthesis, drying 6-10 mm diam; ovules many (usually 10-20) per locule.
7. Leaf blades narrowly ovate-elliptic or triangular-sagittate or triangular-hastate, usually 1.8 times longer than wide; posterior rib more than 3 cm long.
8. Leaf blades narrowly ovate-elliptic, posterior lobes about as broad as long, directed toward the base; sinus +/- V-shaped; ovules ca. 20 per locule; Mexico (Chiapas), 0-1,300 m.
P. breedlovei Croat
8. Leaf blades triangular-sagittate to triangular-hastate; posterior lobes typically much longer than broad; sinus usually not V-shaped but parabolic to spathulate; ovules usually 1-2 per locule; Mexico to Colombia, 0-1,900 m.
P. mexicanum Liebm.
7. Leaf blades ovate, usually only slightly longer than wide (rare to 1.9 times longer than wide in P. hederaceum); posterior rib virtually lacking or to at most 1 cm long.
9. Stems drying dark reddish brown, prominently ribbed, usually densely warty; Costa Rica to Ecuador and Suriname; (250)300-900 m.
P. hederaceum (Jacq.)Schott var. kirkbridei Croat

9. Stems drying either green and only weakly striate or light yellowish brown and deeply fissured on drying.

10. Stems drying yellowish brown, prominently ridged, smooth and glossy; spathe tube violet-purple; Costa Rica to Ecuador, 0-1,520 m.
P. purpureoviride Engl.

10. Stems drying greenish, weakly striate; spathe tube green; Mexico to West Indies, widespread in South America
P. hederaceum (Jacq.) Schott

6. Peduncles frequently as long as or longer than the spathe, usually elongate and narrow, drying 3-4 mm diam; ovules 1 or 2 per locule.
11. Leaf blades lacking any obvious primary lateral veins; stems prominently sulcate-ribbed even when fresh; ovules 1 per locule; NE Costa Rica to central Panama; 100-700 m.
P. sulcicaule Croat

11. Leaf blades with obvious primary lateral veins; stems smooth (or at least not regularly and prominently sulcate-ribbed longitudinally when fresh); ovules 2 per locule; Panama (Darién); 850-1,560 m.
P. clewelii Croat


2. Blades with the posterior rib naked and closely parallel to the sinus for usually 1.5 cm or more (sometimes to as little as 1 cm in P. smithii).

12. Stems setose-pubescent; blades thin, membranaceous on drying; spathe tube inflated with considerable space between the inner surface of the spathe and the spadix; pistils elongated at apex into a style, the style to ca 5 mm long; Mexico to Panama, Cuba and northern South America; 0-1,500 (2,500) m.
P. jacquinii Schott
12. Stems glabrous; blades coriaceous to subcoriaceous, firm on drying; spathe not inflated-bulbous at base, fitting tightly over spadix; pistils not at all elongated into a distinct stylar region. 13. Stems prominently and regularly sulcate-ribbed when fresh. 14. Blades less than 24 cm long, lacking obvious primary lateral veins; petioles to 21 cm long; NE Costa Rica to Isthmus of Panama; 100-700 m.
P. sulcicaule Croat
14. Blades more than 26 cm long, with 3-4 obvious pairs of primary lateral veins; petioles more than 29 cm long; S. Mexico to Guatemala; 700-1525 m.
P. verapazense Croat
12. Stems smooth or irregularly fissured but not regularly sulcate-ribbed.  
15. Blades mostly broadly ovate, usually more than 25 cm wide; posterior lobes usually broadly rounded, about as wide as long; stems drying light reddish brown with flaking epidermis.
P. brunneicaule Croat & Grayum
15. Blades mostly ovate-triangular or triangular-sagittate to triangular-hastate, mostly less than 25 cm wide (sometimes broader in P. smithii).   16. Blades sagittate to hastate at base; posterior lobes 2-3 times longer than broad; posterior rib directed straight toward the tip of the blade and 1.5-3.5 cm distant from the lower edge of the blade; Mexico to Panama, 0-1,900 m.
P. mexicanum Engl.   16. Blades cordate or sagittate (rarely hastate in some forms of P. wilburii); posterior lobes usually less than 2 times longer than wide (except sometimes more than 2 times longer in P. wilburii, and then drying reddish brown, not greenish as in P. mexicanum); posterior rib mostly curved along and near the margin of the sinus, rarely more than 1 cm from the lower margin.
17. Cataphylls 2-ribbed; blades usually more than 35 cm long; petiole often with a purple ring at apex; peduncles usually longer than the
spathe; Mexico to Nicaragua, 40-600(1,500) m. P. smithii Engl.
17. Cataphylls 1-ribbed (rarely 2-ribbed); blades usually less than 36 cm long; petioles lacking a purple ring at the apex; peduncles usually shorter than the spathe (except often longer in P. wilburii var. longipedunculatum); central Costa Rica to central Panama, 0-2,000 m.
P. wilburii Croat & Grayum

1. Internodes of mature stems broader than long or sometimes somewhat longer than broad but not elongate with long internodes and scandent stems (possibly somewhat scandent in P. breedlovei and P. sousae); plants mostly appressed- climbing hemiepiphytes.

18. Petioles either densely covered with scales or D-shaped with undulate-winged margins. 19. Petioles terete, less than 1 cm diam, densely covered with conspicuous, spreading scales; blade almost as broad as long, the major veins on the lower surface densely puberulent; Panama to Ecuador; 0-1,300 m.
P. squamipetiolatum Croat
19. Petioles sharply D-shaped or sharply flattened with undulate-winged margins, more than 1.5 cm diam, glabrous, lacking scales; blades much longer than broad; veins of lower surface glabrous; Panama (Chiriquí); 1,100-1,300 m.
P. fortunense Croat
18. Petioles not scaly or winged-margined, but instead smooth and terete to merely obtusely flattened.  
20. Posterior rib naked along the sinus.  
21. Peduncle usually less than 10 cm long.  
22. Blades less than 25 cm long, drying dark brown to yellow-brown above.  
23. Blades ovate-trianular, 1.8-3 times longer than wide; posterior lobes 1.4-1.8 times longer than wide (measured from petiole plexus to tip of lobe for length; middle of lobe for width); inflorescence solitary; Panama (Chiriquí), 1,750-2,100 m.
P. knappiae Croat
23. Blades ovate, 1.3-1.6 time longer than wide; posterior lobes about as broad as long; inflorescences 2-3 per axil.
P. coloradense Croat
22. Blades more than 35 cm long, usually drying green to brownish green to grayish green to dark olive-green (sometimes dark brown in P. zhuanum or blackish in P. smithii) above, reddish brown to yellowish green below.
24. Peduncles less than 9.5 cm long; petioles not markedly flattened on drying, 8-15 mm diam, usually greenish to dark brown on drying. Less than 360 m along the Caribbean coast in Costa Rica.
P. aromaticum Croat& Grayum
24. Peduncles more than 9 cm long; petioles markedly flattened to 3-6 cm wide on drying, often yellowish; 700-900 m, Coclé Province, Panama.
P. zhuanum Croat  
21. Peduncle usually 10 or more cm long.
  25. Leaf blades with margins convex in lower 1/2 of blade; Mexico to Nicaragua; 40-600(1,500) m.
P. smithii Engl.
26. Stem drying light brown; epidermis often flaking; petioles spongiose but drying moderately smooth and flattened to ca. 1 cm wide; blades drying thin and lacking conspicuous secretory canals; 40-1,500 m (mostly less than 600 m), Mexico to Nicaragua.

26. Stem drying dark brown; epidermis folded or cracked but not flaking; petioles firm, drying heavily wrinkled, flattening 3-6 cm wide; blades drying coriaceous with conspicuous secretory canals; 700-900 m, Panama (Coclé Prov.).
P. zhuanum Croat

25. Blades with margins straight to concave in lower 1/2 of blade; Costa Rica and Panama.
27. Leaf blades drying pale yellow-green, lacking any sign of secretory ducts on lower surface; ovules 1 per locule; Costa Rica, 1,350-1,400 m.
P. herrerae Croat & Grayum

27. Leaf blades drying dark olive-green or dark brown, with secretory ducts visible alternating with the minor veins on lower surface; ovules 4-5 per locule; highlands near Costa Rican-Panamanian border; 1,100-1,950 m.
P. cotonense Croat

20. Posterior rib not naked along the sinus or merely weakly and obscurely naked near its base.
28. Blades with posterior lobes turned inward and overlapping; peduncles long and slender, drying ca. 2-4 mm diam; 850-1,560 m, Serrania de Pirre, Darién Prov, Panama.
P. clewellii Croat
28. Blades with posterior lobes never overlapping( except sometimes in P. ferrugineum), usually directed downward or somewhat outward; peduncles stout, usually 5-10 mm diam. on drying.  
29. Spathe barely or not at all constricted near the middle or above the tube portion; sterile staminate portion of the spadix often conspicuously broader than the pistillate portion at anthesis (50% broader); Mexico to Guatemala, 70-2,500 m.
P. advena Schott
29. Spathe usually visibly constricted above the tube (usually somewhat below the middle); sterile staminate portion of the spadix only slightly broader (or even narrower) than the pistillate portion (or not detectable).  
30. Inflorescence 1-3 per axil; spathes less than 11 cm long (except 9.5-18 cm long in P. brenesii).  
31. Primary lateral veins mostly more than 8 pairs; minor veins etched-sunken on upper surface, lower surface more or less bluish green; 800-2,200 m., Costa Rica and Panama.
P. brenesii Standl.
31. Primary lateral veins 4-8 pairs (sometimes to 9 pairs in P. sagittifolium); Mexico and Belize.  
32. Leaf blades ca. 1.6 times longer than wide; ovules 1-7 per locule.  
33. Blades drying gray-green below; sap white; ovules 1 per locule; Belize, less than 500 m.
P. dwyeri Croat   33. Blades drying dark yellow- brown below; sap clear, turning brown?; ovules 4-7 per locule; Panama, 1,600 m.
P. coloradense Croat
32. Leaf blades ca. 1.8 times longer than wide; ovules 2-4(5-8) or ca. 20 per locule; Mexico (Chiapas, 1,300 m) or widespread, Mexico to South America, 150-2,700 m.  
34. Blades ca. 1.8 times longer than wide; inflorescence 1 per axil; ovules 20 per locule; Mexico (Chiapas), 1,300 m.
P. breedlovei Croat
34. Blades 1.85-2 times longer than wide, inflorescences 1-3 per axil.
P. sagittifolium Liebm.
35. Inflorescences 4-6 per axil; spathes 15-23 cm long.

36. Cataphylls usually more than 25 cm long; blades usually more than 55 cm long, drying coriaceous, reddish brown, with minute interrupted ridges on lower surface; Panama, 100-770 m.
P. ferrugineum Croat

36. Cataphylls less than 25 cm long; blades usually less than 55 cm long, drying subcoriaceous, brown to olive-green, smooth or minutely ridged but not with interrupted ridges on lower surface; Mexico (Chiapas), 490-1,400 m.
P. sousae Croat