Philodendron strictum G. S. Bunting,
Phytologia 60: 328. 1986. TYPE: Venezuela. Tachira: San Cristobal÷Chorro del Indio÷Cano Seco÷La Florida, km 20-22 (E of San Cristobal), 1100-1125 m, 6 Mar. 1977, Bunting & Borges 5001 (holotype, NY; isotypes, PT, VEN). Figures 393-395, 397, 398.
Terrestrial or hemiepiphytic; stems stout; inter-nodes 3-4 cm long, 2.5÷5 cm diam., usually broader than long, sometimes longer than broad, dark green to gray-green, semiglossy; roots moderately few, drying dark brown, semiglossy, sparsely scaly; cataphylls 25-40 cm long, unribbed to bluntly 1-ribbed, rarely bluntly 2-ribbed or sharply 1-ribbed, pale green, soft, turning yellowish and persisting semi-intact at upper nodes; petioles (47-56)63-105 cm long, subterete, obtusely D-shaped with faint medial rib, obtusely flattened adaxially, light green to gray-green, weakly glossy, sparsely dark lineate, drying usually light yellow-brown, sometimes blackened; sheath inconspicuous; blades ovate-cordate, conspicuously bicolorous, acuminate at apex (the acumen sometimes in-rolled), cordate, sometimes sagittate at base, (24)38-66(74) cm long, (16)27-52 cm wide (1-1.3 times longer than wide), (0.5÷1 times the petiole length), broadest near the middle; upper surface dark green, semiglossy, lower surface much paler, whitish, matte; anterior lobe (19-28)31-51(57-62) cm long, (19)27-48(53-56) cm wide, (1.7-2.8(3.3) times longer than posterior lobes); posterior lobes 12-23 cm long, 8.6÷26 cm wide, obtuse to broadly rounded; sinus usually spathulate, sometimes hippocrepiform; midrib flat, paler than surface above, convex and darker below; basal veins 7÷10 per side, with 0÷2 free to base, part of the remainder coalesced 1÷12.4 cm; posterior rib sometimes not naked, often obscurely naked for 1.5 cm, rarely 3.5 cm; primary lateral veins 5÷11 per side, departing midrib at a 50÷65¡ angle, deeply sunken above, convex and darker below, usually prominently down turned before meeting midrib; minor veins numerous, fine, indistinct below, arising from both the midrib and primary lateral veins.
INFLORESCENCES erect-spreading, 1-4 or more per axil; peduncle (6)11÷15 cm long, 1-1.5 cm diam., with thin, yellowish epidermis; spathe 13÷17.7 cm long, 2.5-4.3 cm diam. (0.9÷2.3 times longer than peduncle), moderately constricted above the lube (very slick inside), 2.7 cm diam. at constriction; spathe blade light green to whitish, tinged purple-violet (B & K red-purple 3/2.5), sparsely short-white-lineate medially outside, margins paler, (opening elliptic in face view, 10.7 cm long, 4.8 cm wide), light green to whitish and suffused red inside, drying dark to reddish brown; spathe tube green to purple-violet (B & K red-purple 3/2.5) outside, 4 cm diam., maroon or violet-purple inside; spadix sessile; bluntly pointed at apex, 9.2-16 cm long; pistillate portion weakly tapered toward apex, 2.1÷3.9 cm long in front, (1.6)3÷3.3 cm long in back, 0.6÷1.4 cm diam. at apex, 1÷1.5 cm diam. at middle, 1.3÷1.5 cm wide at base; staminate portion 8.9÷11.9 cm long; fertile staminate portion somewhat ellipsoid, sometimes ovate to tapered, 1.1 cm diam. at base, 1.2÷1.3 cm diam. at middle, 8÷ 9 mm diam. ca. 1 cm from apex, broadest in the middle or sometimes just above the base, narrower than the pistillate portion, as broad as the sterile portion; sterile staminate portion narrower than the pistillate portion, 1-1.4 cm diam.; pistils (1.1)2.7-3.4(5.4) mm long, 1.3-1.6 mm diam.; ovary (4)5-6-locular, 1.8 mm long, 1.3-1.7 mm diam., with axile placentation; locules 1.8 mm long, 0.6 mm diam.; ovules 20-28 per locule, 2-seriate, 0.2-0.4 mm long, longer than funicle; funicle 0.1 mm long, adnate to lower part of partition, style 0.7÷0.9 mm long, 1.3÷1.6 mm diam., similar to style type B; style apex flat; stigma subdiscoid, truncate, 1.1÷1.3 mm diam., 0.3-0.5 mm high, covering entire style apex; the androecium prismatic, truncate, oblong, irregularly 4÷6-sided at apex 0.9 mm long, 1.6÷2 mm diam. at apex; thecae oblong, ± parallel to one another, nearly contiguous; sterile staminate flowers blunt, prismatic, irregularly 4÷6-sided, 1.8÷2.9 mm long, 0.9-2.4 mm wide.
INFRUCTESCENCE 2 cm wide; seeds pale yellowish, 0.9 mm long, 0.3 mm diam.
Flowering in Philodendron strictum apparently occurs throughout the dry season and first half of the rainy season in Central America (January through September, though no flowers were seen in May). South American flowering collections have been seen from February and July, and post-anthesis inflorescences (or immature fruits) from January through November. Mature fruits have been seen only from September.
Philodendron strictum ranges from Costa Rica to western Panama, Venezuela (Tachira), Colombia (Antioquia, Choco), and Ecuador (Carchi, Esrneraldas). In Costa Rica, this species occurs at 850 to 1525 m, and in Panama at 680 to 1665 m elevation in Lower Montane rain. Premontane rain, and Tropical wet forest life zones. In Colombia, this species has been collected at 100 to 150 m in Choc6 and Valle Departments, and in Antioquia at 1560 m. In Venezuela, it is known only from the state of Tachira in the south-western part of the country, at 1000 to 1250 m elevation in Premontane wet. forest. It was reported erroneously (owing to a typographical error) by Croat and Lambert (1986) from 110 to 1330 m.
Philodendron strictum is a member of P. sect. Philodendron subsect. Philodendron ser. Impolita. This species is characterized by its usually terrestrial habit; thick stems; short internodes; thick, yellowish, unribbed to bluntly one-ribbed cataphylls persisting semi-intact at the upper nodes; obtusely flattened to D-shaped petioles usually drying pale yellow-brown; and ovate-cordate blades with the lower surface whitish and matte.
Philodendron strictum is most easily confused with P. hebetatum, which shares blades with whitish, matte lower surfaces, as well as yellow-drying cataphylls and petioles. Both species are easily identified by these features alone. The two species are sympatric in at least one area along the Fortuna Dam road in Panama but remain distinct by virtue of their respective habits and blade shapes. Philodendron hebetatum differs in being consistently an appressed epiphyte and in having a triangular-ovate blade vs. a generally terrestrial habit and consistently ovate blades for P. strictum. Juvenile plants of the two species, at this stage both terrestrial, are quite distinct with the blades of P. hebetatum more elongate (2.5÷3 times longer than broad), while those of P. strictum are more broadly ovate (1.2-2.5 times longer than wide).
This species is also easily confused with the often syntypic P. thalassicum, which differs in having blackened rather than pale yellow-brown petioles, cataphylls promptly weathering to pale fibers vs. usually persisting yellowish and semi-intact in P. strictum and internally greenish to white spathes (vs. maroon or violet-purple in P. strictum). In addition (at least in Panama), the petioles of P. thalassicum are more sharply D-shaped vs. obtusely flattened in P. strictum.
A collection from 1875 m elevation in Antioquia Department, Colombia (McPherson 12939), possibly belongs to this species but differs in having reddish brown cataphylls that are more fragmented on drying. It also has the petioles drying dark brown, not yellowish as is typical for the species in Colombia and Ecuador.