Philodendron hebetatum Croat

Hemiepiphytic. Stem appressed-climbing; internodes short, semiglossy, 1–4 cm long, 1.5–2.5 cm diam., longer than broad, green to gray-green, drying yellow-brown; roots moderately numerous per node, drying dark brown, ridged. Cataphylls 12–35 cm long, unribbed, sometimes sharply 1-ribbed near apex (sharply 2-ribbed in South America), medium green, drying light to medium brown, persisting semi-intact at upper nodes, then deciduous with large patches of yellow-brown periderm remaining intact; petioles 27–75 cm long, 0.8–1.8 cm diam., more or less terete, obtusely flattened adaxially, spongy (in South America), dark green to gray-green, surface semiglossy to matte, transversely fissured near apex, drying pale yellow-brown. Leaves erect-spreading; blades ovate-triangular, subcoriaceous, abruptly acuminate at apeax, cordate-sagittate at base, 24–63 cm long, 19–44 cm wide (1.1–2.3 times longer than wide), (0.7–1.2 times longer than petiole), equal to or longer than petiole, margins concave, broadly undulate, upper surface semiglossy, dark green, drying conspicuously yellow-brown, semiglossy, lower surface opaque whitish, matte, paler; anterior lobe 19.5–49.5 cm long, 14.5–42 cm wide (1.9–3.6 times longer than posterior lobes); posterior lobes 7.1–20.2 cm long, 7.3–20.5 cm wide, obtuse to rounded; midrib broadly concave, paler than surface above, thicker than broad, weakly glossy, darker than surface below; basal veins 6 per side, with 1–2 free to base, second and third veins coalesced ca. 3 cm; posterior rib naked for 2.5–3.5 cm long; primary lateral veins 6–11 per side, departing midrib at a 35–50xv degree angle, weakly sunken above, convex and darker than surface below; minor veins moderately distinct, fine, intermittent below, arising from both the midrib and primary lateral veins. Inflorescences 1–5 per axil; peduncle 4–11 cm long, 4–11 mm diam., white-lineate to coarsely white-streaked toward apex and on spathe base. Spathe 11–17.5 cm long, 2–3.5 cm diam. (1.3–3.1 times longer than peduncle), white-speckled, semiglossy, constricted above the tube, 9–11 mm diam. at constriction; spathe blade green to whitish, sometimes rose-red outside, green to whitish or sometimes rose-red and white-speckled inside; spathe tube oblong-ellipsoid, 4–7 cm long, usually dark green or sometimes purple to violet-purple to red or pinkish outside, reddish to pale violet-purple (dark maroon=SoAm) inside. Spadix white, cylindrical, 12.9–16.6 cm long, broadest near the base, constricted near the middle; pistillate portion whitish, cylindrical to ovoid, 3.8–8.9 cm long, 7–16 mm diam.; staminate portion 9.3–13.4 cm long; fertile staminate portion cylindrical, 8–13 mm diam., broadest at the base, narrower than pistillate and sterile portions; sterile staminate portion as broad as or narrower than the pistillate portion, 1–1.3 cm diam.; pistils glossy, 2.1–4(5.8) mm long, 1.2–2.6 mm diam.; ovary (4)5–8-locular, walls embedded with granular, crystal-like particles, locules 1.3–3.2(4.5) mm long, 0.4–0.6 mm diam., with axile placentation; ovules (4)20–24 per locule, arranged in series of 2, 0.2 mm long, about equal in length to funicle; funicle 0.1 mm long, adnate to lower part of axillar wall, style 0.4–0.7 mm long, 1.2–2.6 mm diam., similar to style type B; style apex flat or rounded; stigma subdiscoid, 1–1.5 mm diam., 0.2–0.5 mm high, covering center of style apex; the androecium truncate, margins 4–6-sided, sometimes scalloped; thecae oblong, 0.3–0.4 mm wide, contiguous, more or less parallel to one another; sterile staminate flowers 3–6-sided, 1.5–2.5 mm long, 1.4–1.8 mm wide. Berries white, with purple stigmas; seeds 2–3,6,10–12,18–25 per locule, (1–5)8–11 mm long, 2–3 mm diam.

Flowering in Philodendron hebetatum apparently occurs throughout the dry season and first part of the rainy season in Panama, from December through July. Post﷓anthesis inflorescences have been collected from January through October (except September). Immature fruits have been collected in June and July. South American collections roughly match with those from Panama. Philodendron hebetatum is a member of P. sect. Philodendron subsect. Philodendron ser. Impolita. This species is characterized by its generally appressed﷓climbing hemiepiphytic habit, short internodes, usually unribbed, semi﷓intact persistent cataphylls with large patches of yellow﷓brown epidermis remaining intact, petioles equaling or exceeding the blade in length and drying conspicuously yellow﷓brown and smooth (thus clearly demarcated from the blade), and markedly bicolorous, narrowly ovate﷓triangular blades usually concave along the margin and matte and whitish on the lower surface. The petioles of P. hebetatum are variable, being typically terete to obtusely D﷓shaped in Central America but sharply C﷓shaped to sharply D﷓shaped with acute to bluntly raised lateral margins in South America. South American populations also have the major leaf veins drying yellowish to pale red versus dark red in Central America. It is possible that the South American elements may ultimately prove to be at least subspecifically distinct. Some South American specimens of P. hebetatum are particularly noteworthy. Holm﷓Nielsen et al. 25665 from Ecuador differs from other collections in having the petiole epidermis drying paler yellow and the immature spathes drying a paler reddish brown. A collection from Nariño Department, Colombia, near Junín (Croat 72425A) is unusual in having the margins of the anterior lobe markedly concave but perhaps belongs also this species. Philodendron hebetatum is easily confused, especially in live condition, with P. thalassicum, which may also have triangular﷓ovate blades much paler and matte on the lower surface. The latter differs, however, in having petioles which are sharply D﷓shaped and dry blackened rather than conspicuously yellow﷓brown. In addition, P. hebetatum has spathes reddish within while in P. thalassicum they are greenish within. Philodendron hebetatum is also similar to to P. strictum G.S. Bunting, which differs by its usually terrestrial habit, more or less reclining stems and by its broadly ovate blades. Both species have pale, matte lower blade surfaces, yellow﷓brown drying petioles and cataphylls with persistent patches of intact, yellowish brown epidermis. The lower blade surface in both species is covered with a wax﷓like substance and dries with a fine reticulate pattern (areolate at 7x or higher magnification). Philodendron strictum ranges from Costa Rica to Panama and Venezuela at 650 to 1900 m elevation. In Panama, where both species occur together along the Fortuna Dam Road, P. strictum tends to occur at higher elevations than does P. hebetatum. Philodendron hebetatum is also similar to an unpublished species (Croat 55457) occurring at 3000 m elevation in Cundinamarca Department, Colombia. The latter differs in having ovate blades matte on both surfaces and with more numerous, more closely spaced primary lateral veins. Juvenile plants (Croat 56049, 56174, 56213, 69291; Valle and Chocó Departments, Colombia) have oblong﷓elliptic leaf blades acute at the base but the petiolar epidermis already is colored as in adult plants. Leaves of older plants become increasingly rounder and broader at the base and finally subcordate to cordate. An unusual collection is Croat 49298 from Chocó Department in Colombia, with has leaves only shallowly cordate, even though they are in the upper end of the size range for adult plants of this species. Sanchez et al. 553, a collection from Colombia (Antioquia) is noteworthy in being from 1880 m elevation and in being terrestrial. It is probably P. hebetatum. Holm﷓Nielsen et al. 25665 from Ecuador (Esmeraldas) differs from other South American collections in having paler, more flaky epidermis on the petioles and smaller, more or less sessile (perhaps immature) inflorescences. Perhaps it represents another species. South American collections of P. hebetatum differ from those of Panamanian material in that the petioles dry dark brown rather than yellowish. Croat 61396 is unusual in apparently having only four ovules per locule.