Philodendron brevispathum Schott

Terrestrial or hemiepiphytic. Stem scandent, coarsely scabrous, densely covered with trichome-like, often branched scales; internodes elongate, 7.5–14(23) cm long, 8–15 mm diam., longer than broad, epidermis reddish brown, loosening and flaking, without fissures; roots drying tan to dark brown, few per node. Cataphylls 6–9 cm long, soft, unribbed, green, drying dark reddish brown, eventually deciduous. Petioles 10–43 cm long, 3–7 mm diam., subterete to bluntly C-shaped, somewhat spongy. Blades ovate to ovate-triangular, concolorous, semiglossy, thin, acuminate at apex, cordate at base, 16–36 cm long, 11–26 cm wide (1.4–2 times longer than wide), (0.8–1.6 times longer than petiole), broadest at or above middle, upper surface semiglossy, lower surface semiglossy; anterior lobe 12–30 cm long, 10.8–24 cm wide (1.3–2.4 times longer than posterior lobes); posterior lobes somewhat triangular to narrowly triangular to rounded, or rounded to with hastate or flaring lobes, 5–15 cm long, 4.9–11.5 cm wide, subacute; sinus narrow or sometimes V-shaped, 9–11 cm deep. Midrib sunken above, convex to raised, drying slightly paler below; basal veins 3–4 per side, with 1 free to base, coalesced 4–10 mm, or with 2–3 veins colaesced to 3 or 4 cm; posterior rib not naked or obscurely and briefly naked to 0.5 cm long; primary lateral veins (3)4–5 per side, departing midrib at a 55–70 degree angle, gradually ascending to the margins, weakly sunken above, convex and drying slightly darker below; interprimary veins almost as conspicuous as primary lateral veins; minor veins arising from both the midrib and primary lateral veins; tertiary veins visible and darker than surface below. Inflorescences erect, 1 per axil; peduncle 1–7 cm long, 2.5–5 mm diam., subterete. Spathe 6–10.5 cm long, (1.4–4.6(9) times longer than peduncle); spathe blade green outside, red inside; spathe tube green to greenish white outside, 4–4.5 cm long, 2–2.5 cm diam., green to white inside. Spadix sessile; 7–9.5 cm long, whitish to yellowish; pistillate portion 2–3 cm long, 3.5 cm diam. throughout; staminate portion 5–7 cm long; fertile staminate portion 5–10 mm diam.; sterile staminate portion 5–6 mm diam.; ovary ca. 6-locular, with axile placentation; ovules 6–14 per locule, 0.3–0.4 mm long, longer than funicle; funicle 0.2 mm long, adnate to lower part of partition, style similar to style type B; stylar canals emerging at base of pronounced apical depressions; style apex drying dark brown with a pale undulate margin and a central solitary stigmatic pad; the androecium truncate, prismatic, margins distinctly scalloped, irregularly 4–5-sided, 0.9 mm long; thecae oblong, 0.4 mm wide, nearly contiguous. Infructescence with peduncle 4 cm long, spathe 5–6 cm long; spadix, 3.5–4 cm long, 2.5 cm wide; berries pale yellow, 6 mm long, 3 mm diam.; seeds 4–6 per berry, oblong to weakly ovoid, 1.4 mm long, 0.4–0.5 mm diam.

Flowering in Philodendron brevispathum is apparently aseasonal, perhaps owing to its habitat along and near streams. Flowering collections have been made in February through April, July, August, and November. Immature fruiting collections were also made throughout most of the year, January through April, July, September, and November. Though long known only from the Caribbean coast of Panama, Philodendron brevispathum is now known to be a locally rare but more widespread species with special ecological requirements. It ranges from Nicaragua to Panama at 0--280 m with disjunct populations in South America, there ranging from Venezuela to Brazil (Amazonas), Colombia (Vichada, Meta), Ecuador (Napo), Peru (Loreto), and Bolivia, at elevations of 60 to 230 meters. Philodendron brevispathum is a member of P. sect. Philodendron subsect. Solenosterigma. It grows as a low hemiepiphyte or in drier areas as a terrestrial herb, usually along streams, on river banks, or in swamps. Maguire 36157 is unusual in being reported as a vine growing to 13 m in trees. The species is recognized by its scandent habit, its thin ovate to ovate﷓triangular leaf blades with rounded to hastate posterior lobes and a generally narrow (sometimes V﷓shaped) sinus and especially by the stems that are densely covered with trichome﷓like often branched scales and dry with a flaky brown periderm. While the posterior leaf lobes are commonly somewhat triangular (and may even be narrowly triangular and subacute at apex), they may be nearly round on the same collection (Davidse & Gonzalez 12973). Bunting (1988) recognized the South American material as P. brevispathum subsp. holmquistii (G.S. Bunting) G.S. Bunting, characterized having 7﷓-14 ovules per locule (versus 14﷓-18 for the typical material in Central America) and pistils with the apex convex with 3﷓-4 stigmatic pads. Yet, my observations indicate that Central American material also has 6﷓-14 ovules per locule. This species is closest to P. muricatum Willd. ex Schott (an older name) and may not be separable from it. The latter species is distinguished by having densely verrucose﷓warty petioles and usually smaller blades with more rounded lobes. However, some collections with verrucose petioles such as Steyermark et al. 115076 and Liesner 9056 from Delta Amacuro, Venezuela and Krukoff 7250 from southern Amazonas state of Brazil (the type of P. amplectans A.C. SM., a synonym of P. muricatum) have narrow, more or less triangular blades like those of P. brevispathum. On the other hand, not all specimens of P. brevispathum have similar lobes. Central American material commonly has more rounded or elongate lobes which are turned somewhat inward but some sheets (Burger & Antonio 11236) have blades identical to those of South American plants. In addition, some South American collections (Croat 58586, Davidse 4294) have the posterior lobes noticeably rounded and scarcely longer than broad. Despite this variation, the verrucose petiole character is adequate to separate P. brevispathum from P. muricatum. Philodendron brevispathum has also been confused with P. jacquinii Schott, but that species has merely puberulent stems (with trichomes simple and unbranched), thinner, more broadly ovate leaves (often also puberulent on the petiole and lower midrib), a conspicuously bulging spathe tube, and much elongate styles).

Philodendron arcuatum K. Krause, Pflanzenr. IV 23Db(Heft 60): 72. (1913). Type: Bolivia. Pando Río Acre, at Cobija (on Brazilian border, SW of Río Branco), 11º02'S, 68º44'W, Ule 8819 (holotype, B). Philodendron holmquistii G.S. Bunting, Acta Bot. Venez. 10: 297. (1975). Philodendron brevispathum Schott subsp. Holmquisti, (G.S. Bunting) G.S. Bunting, Phytologia 64(6): 466–467. (1988). - Type: Venezuela. Amazonas: Pueblo Viejo, open zone between the Río Pacimoni and the forest, 100 m, 1º50'N, 66º30'W, Steyermark & Bunting 102495 (holotype, VEN; isotype, MY).