Planta plerumque terrestris, interdum hemiepiphytica; caulis scandens; internodia 3--15 cm longa, 1.3--1.7 cm diam.; cataphylla mollia, 7--15 cm longa, acute D-formata, plerumque acute 2-costata, decidua; petiolus subteres vel obtuse complanatus adaxialiter, 16--55 cm longa, 5--10 mm diam.; lamina 22--35 cm longa, 16--31 cm lata, triangulari-ovata, lobis posticis angustis, patentibus; inflorescentia 1--2; pedunculus 11--29.5 cm longus, 5--10 mm diam., subteres; spatha 8.7--18 cm longa, saepe viridis omnino; lamina spathae extus viridi vel flaviviridi aut eburnea vel citrina, intus pallide viridi, cremea, albida aut suffusa rubra; tubo spathae extus virenti vel atriviridi, intus atrimarronino vel atripurpureo, rubro, rubriviolaceo aut violaceo; pistilla (5)6--7(8)-locularia; loculi 1--2-ovulati; baccae aurantiacae.

Usually terrestrial, sometimes hemiepiphytic; internodes 3--15 cm long, 1.3--1.7 cm diam.; cataphylls soft, 7--15 cm long, sharply D-shaped, usually sharply 2-ribbed, sometimes unribbed or sharply 1-ribbed; petioles 16--55 cm long, 5-10 mm diam., obtusely flattened or bluntly D-shaped adaxially; blades triangular-ovate with spreading lobes, 22--35 cm long (averaging 28 cm), 16--31 cm wide (averaging 21 cm; 1.03--1.4 times longer than wide, averaging 1.3 times), (0.6--1.3 times longer than petiole); sinus usually arcuate or arcuate with decurrent petiole. INFLORESCENCES 1 or 2 per axil; peduncle 11--29 cm long, 5-10 mm diam.; spathe 8.7--18 cm long; spadix 6.7--11.2 cm long; pistillate portion 2.8--5.5 cm long; ovary (5)6--7(8)-locular; ovules 1--2 per locule. Berries bright orange (mature) or white (immature); seeds yellow-orange, narrowly ellipsoid.

The flowering phenology of Philodendron wilburii var. longipedunculatum is poorly known. It appears to be bimodal or, in any event, unlike the pattern of any other species. All flowering collections have been made between September and April, in the late rainy season and throughout the dry season. However, post-anthesis flowering collections from July make it obvious that some flowering also takes place during June or July, perhaps both months. Other post-anthesis collections are from January through April and also in September. The only mature infructescence was collected in March.

Philodendron wilburii var. longipedunculatum is known principally from eastern Costa Rica and western Panama with an outlying population at Tapantí in Cartago Province, at 900 to 1400 m elevation, especially on the Atlantic slope but also on the Pacific slope at lower elevations (40 to 450 m). The Pacific coastal populations range from Carara to the Osa and Burica Peninsulas in Puntarenas Province, with outlying populations on the Azuero Peninsula and in the Canal Area of Panama.

Philodendron wilburii var. longipedunculation is distinguished by the sharply two-ribbed, deciduous cataphylls, subterete, moderately firm petioles, typically triangular-ovate blades often drying reddish to yellowish brown and usually with narrow, spreading lobes, and very long-pedunculate inflorescences.

The highland populations differ from those of the lowlands in having longer posterior lobes which are narrower and more prominently directed outward, averaging about 11 cm long (versus about 8 cm long for the lowland populations). The lowland populations have proportionately narrower blades (owing to their lack of long, outward-directed lobes), averaging 1.6 times longer than wide (versus 1.3 times for highland populations).

Lowland populations in the vicinity of the Burica Peninsula have somewhat thicker blades drying with a minutely pustular or granular lower surface with the secretory ducts mostly not visible. In contrast, blades of highland populations dry darker brown to almost blackened on the upper surface and are smooth on the lower surface with the secretory ducts clearly visible and alternating with the minor veins.

The Azuero population, represented by Croat 34476, has leaf blades that dry somewhat blackened and have posterior lobes somewhat less narrowed and less directed outward than those of the highland Chiriquí populations. The Canal Area populations, represented by Croat 12351 and Croat & Zhu 77083, also differ in having proportionately longer petioles than material elsewhere. The latter collection is also exceptional in having four inflorescences per axil.

Grayum & Sleeper 3435 is a noteworthy collection from Tapantí, Cartago Province, Costa Rica. It is unusual both in being from well out of the normal range of the variety, but also in having narrower leaf blades and shorter peduncules. Perhaps it represents another taxon.

Additional specimens examined.