Philodendron hederaceum (Jacq.) Schott,
Wiener Z. Kunst. 1829: 780. 1829. Figures 221--223.
Arum hederaceum Jacq., Enum. Syst. Pl. 31. 1760. TYPE: t. 51, fig. D in Plum., Pl. Amer., 1756 (holotype).
Hemiepiphytic vine; growing to often high in trees, stem appressed-climbing, eventually scandent, often pendent, sap clear, turning honey-colored, leaf scars 7--15 mm long; internodes weakly flattened on one side, sometimes with 2 sharply raised on the side above the petioles, usually weakly glossy, sometimes matte, pale to medium green, minutely speckled to striate, usually smooth when fresh, but drying minutely ridged, sometimes prominently ribbed throughout its circumference (the ribs smooth to prominently warty), (2)10--28 cm long, 1--2.5(3.5) cm diam., dark green, usually drying green, sometimes reddish; roots brown, to 10 cm long, many at nodes; cataphylls 6--10 cm long, unribbed, weakly 1-ribbed, or bluntly to sharply 2-ribbed, pale green, deciduous; petioles (6)9.7--27(33) cm long, 6--10 mm diam., terete to subterete, pale green, firm, flattened adaxially, pale green, surface smooth, weakly glossy to matte; blades broadly ovate, subcoriaceous to coriaceous, semiglossy to matte, acuminate to long acuminate, sometimes cuspidate at apex (the acumen inrolled, 0.5--0.9 mm long), 11--40(50) cm long, 8--24(34) cm wide (1.2--1.9) times longer than wide), (ca. 1.3(1.5) times longer than petiole), margins hyaline to pale yellowish, upper surface dark green, sometimes subvelvety, lower surface slightly paler, often purplish violet, drying gray-green to yellow-green; anterior lobe 9--30(41) cm long, 9--24(29) cm wide ((2)2.4--3.7(6.3) times longer than posterior lobes); posterior lobes 3--10(14) cm long, 4.3--15.7 cm wide, directed inward and sometimes overlapped, obtuse to rounded; sinus usually deeper than broad, mostly spathulate, rarely hippocrepiform, 3--7 cm deep; midrib convex to flat or sunken, concolorous or slightly paler than surface above, convex, concolorous below; basal veins (3)4--5(6) per side, with (0)1--2 free to base, part of the remainder coalesced to 1.5--2 cm cm; posterior rib not naked; primary lateral veins 2--6 per side, departing midrib at a 35--55E angle, more or less straight to the margins, sunken to weakly raised, slightly paler than surface above, convex and paler than surface below; minor veins obsured to moderately distinct, arising from both the midrib and primary lateral veins. INFLORESCENCES erect or pendent, 1 per axil; peduncle (2-3)4--15.7 cm long, 8--12 mm diam., pale green, sometimes tinged purple, matte; spathe subcoriaceous to coriaceous, 9--16.6(24) cm long, (0.9--2.6(3.3) times longer than peduncle), weakly constricted above the tube, 1.3--3.6(5.7) cm diam. at constriction, usually green, sometimes yellowish white, yellowish green, or cream to creamy-white throughout; spathe blade sometimes purple tinged outside, 1.2--3.6 cm diam. when furled, pale green, greenish yellow, sometimes tinged red inside; spathe tube dark green, sometimes tinged reddish maroon outside, 5--6 cm long, 1.5--4.9(6.9) cm diam., maroon, dark red, crimson, or purple at base inside; spadix stipitate to 5--10 mm long, dark maroon; 12--20 cm long; pistillate portion pale greenish white to green, 3.5--6 cm long, 1.5 cm diam. at base, 1.7 cm diam. at middle and near apex; staminate portion 7--11 cm long; fertile staminate portion creamy white to pinkish, broadest at base, weakly constricted ca. 1 cm above sterile portion then more or less uniform to near apex, 1.4--2.2 cm diam. at middle, 9 mm diam. ca 1 cm from apex; sterile staminate portion 1.6 cm diam.; pistils 4--9.2 mm long, 1.8--3.1 mm diam.; ovary 4--6(7)-locular, 8 mm long, locules 8 mm long, 1.4 mm diam., with axile placentation; ovules 20--25 per locule, 0.1 mm long, 2-seriate; funicle 0.1--0.3 mm long, adnate to lower part of partition, style 1.1 mm long, 2.9 mm diam., similar to style type B; style apex flat or somewhat rounded, drying concave with a pale margin and 4--6 paler, flat to weakly sunken circular areas associated with the stylar pores; stigma 3--4-sided, light brown to reddish, drying light brown 1.8--3.3 mm diam., 0.35 mm high, margins thin; sterile staminate flowers blunt, irregularly 4--5-sided, 2.2 mm long, 1.3 mm wide. INFRUCTESCENCE pendent, often on leafless stems; spathe dark green, weakly glossy outside; pistillate spadix 5--8 cm long, 3.5--4 cm diam.; berries greenish white; seeds 1--2 per locule, somewhat orange, many per berry, more or less ovoid to oblong ellipsoid, (1.5)3--5 mm long, 2.5--4 mm diam., with weak constriction (nipple) and densely covered with raphide cells. JUVENILE plants with upper blade surface dark green, sometimes reddish green, with glistening minute close papillations, lower surface somewhat maroon; veins less conspicuous.
Philodendron hederaceum ranges throughout the West Indies and from Mexico throughout Central America and much of South America, at sea level to 1200(1500) m elevation. In South America it extends from as far south as Los Ríos Province in coastal Ecuador to Trinidad, Venezuela, the Guianas, Brazil, Ecuador, Peru, and Bolivia on the Atlantic drainage of the continent.
Philodendron hederaceum is a member of P. sect. Philodendron subsect. Solenosterigma. This species is distinguished by its scandent habit, long internodes, deciduous cataphylls, ovate-cordate, long-petiolate leaves, and solitary inflorescence with usually green spathes with the tube reddish to purplish within.
Philodendron hederaceum is most easily confused with P. purpureoviride which is a vine with similar leaves. See that species for difference.
Philodendron hederaceum is also somewhat similar to P. jacquinii, but the latter differs in its generally pubescent stems, petioles and major veins of the lower blade surface, its thinner leaf blades, swollen spathe tube, and broad pistillate portion of the spadix with elongate styles.
The taxa here treated as Philodendron hederaceum and P. jacquinii have long been confused nomenclaturally. The former name is based on Arum hederaceum, first validly published by N. J. Jacquin (1760) in his Enumeratio Systematica Plantarum. Jacquin cited only a Plumier (1756) plate (t.51, fig. d), which thus must be accepted as the holotype of the name (Greuter et al., 1994; Art. 9.1, Note 1). Three years later, Jacquin (1763), in his Selectarum Stirpium Americanarum Historia, published his own plate (t.152), identified as A. hederaceum but actually depicting a different species from Cartagena, Colombia, namely, that treated in this revision as P. jacquinii Schott. These two species are fortunately sufficiently different in appearance that even drawings of sterile plants, such as that of Plumier, are unmistakable. This mistake by Jacquin has caused considerable confusion, since several authors, including Kunth (1841), Engler (1899), Krause (1913), Dugand (1945), and Bunting (1963b, 1995), have misapplied the name P. hederaceum based on Jacquin's 1763 publication.
Schott, however, understood the problem. He had already transferred Arum hederaceum to Philodendron (Schott, 1829) and in his treatment for Synopsis Aroidearum (Schott, 1856) he described P. jacquinii, explicitly basing it on Jacquin's 1763 plate. Schott (1856) also placed P. hederaceum sensu Kunth into synonymy under his newly described P. jacquinii. However, he included P. hederaceum in his grex Macrobelium, while treating other synonyms of P. hederaceum in grex Solenosterigma. Names so treated were: P. scandens, P. prieurianum, P. oxycardium, P. cuspidatum, and P. micans.
Engler (1899), followed by Krause (1913), treated the species herein called P. hederaceum as four distinct species, P. prieurianum, P. scandens, P. oxycardium, and P. micans. Both Engler and Krause erred in treating Arum hederaceum Jacq. as a questionable synonym of P. hoffmannii (= P. jacquinii), citing Jacquin's (1763) t. 152 as the type.
Despite the confusion by Engler and Krause, Standley and Steyermark (1958b), in the Flora of Guatemala, correctly dealt with the taxonomy of P. hederaceum, citing P. scandens, P. oxycardium and P. miduhoi in synonymy thereunder. Their treatment of P. jacquinii was incorrect, since they cited that name under the later synonym P. hoffmannii Schott (1858). In this regard they followed Krause (1913). Thus, despite the confusion by Engler and by Krause, the nomenclature of these species was essentially rectified as early as 1958, to the species as P. oxycardium or P. cordatum hort. (non Vell.).
Bunting (1963b), apparently following the lead of Dugand (1945), was aware of the Plumier illustration cited by Jacquin but seemed to believe that it had no bearing on the application of the name because it had been published prior to 1753, the starting date for botanical nomenclature. He also referred to Jacquin (1763) as the "initial" publication of Arum hederaceum, presumably in the erroneous belief that the name had not been validly published in Jacquin (1760). Bunting (1963a) accordingly applied the name P. hederaceum to the species here called P. jacquinii and the obscure P. scandens K. Koch (1853) for the species herein called P. hederaceum. Certainly the epithet P. scandens was not in general use up until that time because most horticultural works (Birdsey, 1951) still referred to the species as P. oxycardium Schott.
Other, more practical matters substantiate that Plumier's (1756) rather crude drawing depicts the species here treated as P. hederaceum, rather than the one called P. jacquinii (accurately illustrated by Jacquin in 1763). Plumier's text associated with t. 51, fig. D states that the plant grew in Martinique, known to have been visited by Plumier (Urban, 1898: 123). Philodendron hederaceum is a widespread species in the West Indies and occurs on Martinique, while P. jacquinii, though also widespread, is not known from the Lesser Antilles. The epithet hederaceum connotes an ivy-like growth habit and aspect, apt for the species to which the epithet is here applied, but not for P. jacquinii. The application of the name P. hederaceum, as explained above, is unambiguous, whereas that of P. scandens, the name used during the last 30 years for this plant, is highly dubious, as it is based on a sterile Koch specimen of unknown origin, lacking an extant type specimen or even illustrations.
Article 57.1 of the Tokyo Code (Greuter et al., 1994) states that "A name that has been widely and persistently used for a taxon or taxa not including its type is not to be used in a sense that conflicts with current usuage unless and until a proposal to deal with it under Art. 14.1 or 56.1 has been submitted and rejected." I consider that this Article does not apply in the present case, since the name P. hederaceum was used in the sense, including its type, as recently as 1958, in a higher regional flora (Flora of Guatemala), which is the most recent published treatment of Araceae for any Central American country, and still reigns as the standard work throughout the region.
In Central America, P. hederaceum is here divided into three varieties. Philodendron hederaceum var. hederaceum and P. hederaceum var. oxycardium (Schott) Croat are only distinguishable on the basis of their juvenile leaf blades. In P. hederaceum var. hederaceum, the juvenile blades are velvety with a silky sheen on the upper surface, whereas the juvenile blades of P. hederaceum var. oxycardium are glossy on the upper surface. These juvenile forms were formally treated by Bunting (1968) as P. scandens forma micans.
The third newly recognized variety, P. hederaceum var. kirkbridei Croat is distinguishable by its adult stems that dry brown and are deeply sulcate with prominent ridges. This taxon also differs in occurring at higher elevations.
The following key separates the three varieties of P. hederaceum in Central America. For anatomical differences see Bunting (1968).
Key to the varieties of P. hederaceum
1. Adult stems weakly sulcate on living plants, moderately to conspicuously sulcate and reddish brown upon drying, usually densely warty; spathe tube dark red to red-purple inside; Costa Rica, Panama, Ecuador, and Suriname, mostly 450--900 m elevation. var. kirkbridei
1. Adult stems smooth, drying mostly green, weakly striate, never minutely warty; spathe tube green(sometimes weakly tinged reddish) inside.
2. Juvenile blades velvety with a lustrous sheenon the upper surface, often tinged purplish on the lower surface; apparently ranging throughout the range of the species in Mexico, Central America and to West Indies and South America (including Amazonian basin). var. hederaceum
2. Juvenile blades glossy on the upper surface, green on the lower surface; known only from the Gulf slope of Mexico in Veracruz, northern Oaxaca, and Tabasco, but possibly also found in Jamaica var. oxycardium