Philodendron aromaticum Croat & Grayum, sp

Philodendron aromaticum Croat & Grayum, sp. nov.

TYPE: Costa Rica. Limón: 3.5 airline km S of Islas Buena Vista in the Río Colorado, 16 airline km SW of Barra del Colorado, 10-- 120 m, 10E39'N, 83E40'40"W, 15--16 Sep. 1986, Davidse & Herrera 31212 (holotype, MO--3582209--10; isotype, US). Figures 66--68.

Planta plerumque epiphytica; internodia 2--3 cm longa, 1.5--3.5 cm diam.; cataphylla acute 2-costata, decidua; petiolus subteres, 33.5--66 cm longus, subspongiosus; lamina ovato-cordata, 33--55 cm longa, 17--26 cm lata, in sicco canoviridis supra, viridis vel brunneiviridis infra; inflorescentia 1; pedunculus 4.5--9.4 cm longa; spatha 15--20 cm longa, lamina spathae extus atriviridi, intus pallide marronina vel alba; tubo spathae atrimarronino; pistilla 9--10(11)-locularia; loculi 2--3-ovulati.

Usually epiphytic, sometimes hemiepiphytic (often occuring high in canopy), rarely terrestrial (accidentally); stem usually appressed-climbing, creeping, brownish, sap sweet, turpentine- to burseraceous-scented; internodes weakly glossy, minutely striate longitudinally, 2--3 cm long, 1.5--3.5 cm diam., usually broader than long, dark to medium green, drying brown, epidermis fissured longitudinally; roots moderately few, drying reddish brown; cataphylls sharply 2-ribbed, D-shaped, deciduous, margins sharply raised.
LEAVES erect-spreading to spreading; petioles 33.5--66 cm long, more or less terete, somewhat spongy, dark green, obtusely to weakly flattened adaxially, surface weakly glossy, not noticeably marked, drying 8--15 mm diam., usually greenish dark brown; blades ovate-cordate, subcoriaceous, glossy, weakly bicolorous, acuminate to long-acuminate at apex (the acumen inrolled, 7--11 mm long), cordate at base, 35--55 cm long, 17--26 cm wide (2.1 times longer than wide), (0.8--1 time longer than petiole), margins weakly undulate; upper surface dark green, semiglossy, drying gray-green, lower surface glossy to semiglossy, paler, drying green to brownish green; anterior lobe 30.5--41 cm long, 16--26 cm wide (2.6--2.9 times longer than posterior lobes); posterior lobes 10.5--15.8 cm long, 7--13 cm wide, rounded at apex; sinus spathulate, 12 cm deep; midrib flattened, slightly paler than surface above, raised to convex, paler than surface below; basal veins 5--6 per side, with none or rarely 1 free to base, two to three veins coalesced 2.7--5.5(6.3) cm; posterior rib naked for 4 cm; primary lateral veins 5--7 per side, departing midrib at a 70--80E angle, straight to the margins, weakly and narrowly sunken above, convex and paler than surface below; minor veins moderately obsure to clearly visible below, arising from both the midrib and primary lateral veins.

INFLORESCENCES 1 per axil; peduncle 4.5--9.4 cm long, 0.08--0.15 cm diam., green, weakly striate; spathe semiglossy, 15--20 cm long, (2.1--3.3 times longer than peduncle), constricted above the tube, dark green throughout, pale maroon to white inside; spathe tube oblong-ellipsoid, weakly wrinkled longitudinally outside, 6--9 cm long, dark maroon, suffused onto blade inside; spadix sessile; greenish white to white throughout, oblong, 12--16.9 cm long; pistillate portion creamy white to pale green, cylindrical, 5--13 cm long, 6--12 mm diam. at apex, 12 mm diam. at middle, 5--10 mm wide at base; staminate portion 7--11 cm long; fertile staminate portion white, ellipsoid, 1 cm diam. at base, 1.4 cm diam. at middle, 6 mm diam. ca. 1 cm from apex, broadest at the middle, slightly broader than the pistillate portion, narrower than the sterile portion; sterile staminate portion broader than the pistillate portion, white, 1.5 cm diam.; pistils 3 mm long, 1.1--1.3 mm diam., ovary 9--10(11)-locular, 1.8 mm long, 1.2 mm diam., with sub-basal placentation; ovules 2--3 per locule, contained within translucent or transparent ovule sac, 0.3 mm long, more or less equal in length to funicle, style similar to style type B; style crown about as broad as ovary; central style dome well developed; style apex with central domes; stigma discoid, weakly lobed, 1.1 mm diam., 0.2--0.3 mm high, covering entire style apex, depressed medially; the androecium margins mostly 5-sided, sometimes 4--6-sided; thecae oblong to ovate, 0.4 mm wide.

Flowering phenology in Philodendron aromaticum is unclear since too few collections exist, although present collections might suggest a bimodality of flowering. Post-anthesis collections have been made in September, October, and again in February. Immature fruiting collections have also been made in the same months and mature fruiting collections have been made in September.

Philodendron aromaticum is endemic to the Atlantic slope of northwestern Costa Rica from sea level to 360 m elevation in a Tropical wet forest life zone.

Philodendron aromaticum is a member of P. sect. Calostigma subsect. Macrobelium ser. Macrobelium. The species is characterized by its thick, bare, short internodes, sharply two-ribbed, deciduous cataphylls, moderately spongy, obtusely flattened petioles longer than the blades, ovate-cordate blades drying gray-green on the upper surface and green to brownish green below, and by its solitary inflorescence with a short peduncle and green spathe which is maroon on the tube within. Also characterisitc is the mucilaginous, aromatic sap of the petioles (whence the name).

Philodendron aromaticum is most easily confused with P. sagittifolium, but that species typically has more elongate blades which dry usually reddish brown, have basal veins free or at least not forming a posterior rib which is naked at the sinus and often more than a single inflorescence per axil. In contrast, P. aromaticum has blades with a prominent posterior rib naked along much of the sinus.

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Additional specimens examined.

COSTA RICA. Cartago. Turialba, Dress 6331 (BH; cultivated). Heredia: San José--Pto. Viejo, vic. of Chilamate, 11.6 mi. N of Cariblanco, 100 m, 10E27'N, 84E05'W, Croat 68382 (CAS, CR, F, G, L, M, MO); La Selva Field Station, Puerto Viejo de Sarapiquí, along El Surá Trail, 100--150 m, 44315 (MO); ca. 100 m, Folsom 8963 (DUKE); 9438 (DUKE); Grayum 2686 (DUKE); Hammel 10733 (DUKE); Croat 61214 (MO). Limón: 2-3.5 airline km SSE of Islas Buena Vista in the Río Colorado, 14 airline km SW of Barra del Colorado, 10--120 m, 10E40'N, 83E40'W, Davidse & Herrera 31136 (CR, MO, US); Cerro Coronel, 10--80 m, 83E39'30"W, 10E40'30"N, 31481 (CR, MO); 20-170 m, 10E41'N, 83E38'W, Stevens 23764 (MO); 2 km W of Río Toro Amarillo, on road W from Guápiles, 275 m, 10E13'N, 83E50'W, Thompson & Rawlins 1197 (CM); Río Sierpe, 5 km NE of La Aurora, Guápiles, 30 m, 10E22'N, 83E31"W, Robles 2189 (CR); 2238 (CR, MO); Río Frío--Limón, vic. of Río Blanco, W of Guápiles, 360 m, 10E12'N, 83E49'W, Croat 68423 (B, CR, K, MO); Refugio Nacional de Vida Silvestre, Río Chirripocito--Río Sardina, 12 m, 10E38'N, 83E45'W, Grayum 9778 (CR, MO).