PHILODENDRON BURGERI
PROTOLOGUE: Philodendron burgeri , published in Systematic Botany Monographs 47: 188 (1996).
Philodendron burgeri Grayum, sp. nov.
Differt a Philodendron seguine fructibus cremeis, a Philodendron aurantiifolio petiolis relative brevioribus, epidermide abaxiali laminis foliorum minute alveolata, pedunculis longioribus segmento femineo spadicis relative breviore.
Type: Costa Rica. Puntarenas: remnant rain forest formations on steep slopes ca. 3–4 km N of Palmar Norte, 140–200 m, 8°58′N, 83°27′W, 17 Feb 1988, Burger, Poveda, Sánchez, Jiménez & Swagel 12333 (holotype: CR!; isotypes: F! K! MO! PMA!).
DISTRIBUTION: Costa Rica to W. Panama: Costa Rica, Panama.
SPECIES DESCRIPTION:
Slender-stemmed vine climbing to at least 10 m on trunks, the branches mostly pendent, the inflorescences arching upward. Internodes 0.3–6.6 cm long, 0.25–0.60 cm wide, green to gray-green, matte, weakly striate (epidermis of young stems thin, brittle, and cracking), drying tan to dark brown, coarsely sulcate. Petiole (4.9–) 5.2–10.4 cm long, P/L=0.31–0.51 (–0.53), extensively sheathed, the sheath involute at base, otherwise horizontally spreading and at least sometimes revolute, adnate or with free portion prolonged apically to ca. 0.6 cm; unsheathed portion of petiole 0.1–0.5 (–0.7) cm long, sulcate above with the margins sharp. Lamina (9.7–) 13.0–21.6 cm long, (2.9–) 3.7–9.6 cm wide, L/W=(2.11–) 2.39–3.61 (–3.87), IQI=(1–) 2–8 (–12), membranous, weakly glossy to semiglossy above, matte below, weakly to moderately bicolored, narrowly lanceolate to narrowly ovate, narrowly to broadly elliptical, or oblanceolate (usually broadest at or below the middle), abruptly or sometimes gradually acuminate apically (the acumen 0.7–1.7 cm long), cuneate to rounded or subtruncate basally; midrib sunken above, convex below; primary lateral veins 5–7 (–10) per side, (0.5–) 1.0–3.9 cm apart, obscurely sunken above, weakly convex below, those in the apical 1/3–1/2 generally indistinct; minor veins visible below, darker; abaxial laminar surface drying without granules, or sparsely to moderately but obscurely granular, alveolate, the reticulate veins obvious but not prominent; white stitching and resin canals sometimes evident (the stitching following the canals where both are visible); adaxial surface very smooth to sparsely or moderately and usually obscurely granular, densely and evenly alveolate, the reticulate veins few (most evident toward margins); no stitching or resin canals, except rarely toward the distal margins.
INFLORESCENCE:
Inflorescences always solitary; cataphylls absent; peduncle (1.0–) 1.6–2.4 cm long, P/S=ca. 0.12–0.13; spathe at anthesis ca. 7.9–15.4 cm long (to 16.5+ cm post anthesis), 1.5–3.2 cm wide (to 3.9+ cm post anthesis), externally green below, yellowish green to whitish green distally, internally uniformly yellow-green (“purple streaking at base of spathe with mottling of purple where spathe joins base of spadix,” Burger et al. 12333); spathe drying sparsely to moderately but obscurely granular and ± densely short white-lineate externally, internally sparsely and obscurely granular, densely and minutely alveolate and moderately white-lineate, with longitudinal secretory striations to ca. 3/5 to apex; acumen of spathe 0.4–2.5 cm long. Stipe of spadix 0.4–0.5 cm long, adnate to spathe; spadix 8.6–13.6 cm long (to 14.4+ cm post anthesis), the fertile male portion 0.7–0.9 cm wide, white; sterile male zone 0.6–0.7 cm long; female portion of spadix 1.9–3.4 cm long (to 7.2+ cm in fruit), F/S=ca. 0.22–0.25, ca. 1.2 cm wide (to 3.7+ cm in fruit); fertile male flowers (1.1–) 1.5–2.3 mm long, 0.6–1.1 mm wide, irregularly polygonal, columnar; sterile male flowers 2.6–3.0 mm long, 1.3–1.4 mm wide, fungoid; female flowers (1.3–) 1.9–2.5 mm long, 0.6–1.1 mm wide, the stylar canals 3–4 (–5). Ripe fruits “de color crema” (Obando 68). Seeds ca. 0.9–1.2 mm long, 0.20–0.30 mm wide, ± straight to sigmoid, finely striate with the striae minutely cancellate, drying light brown and glossy.
ECOLOGY:
Found as a trunk epiphyte, almost exclusively in the Tropical Wet Forest life zone; the type was collected in remnant rain forest formations on steep slopes; 0–250 (–830) m.
ETYMOLOGY:
Named in honor of William C. Burger of the Field Museum of Natural History, Chicago, a leading authority on the Costa Rican flora and a pioneer botanical explorer of the Pacific Tropical Wet Forest realm, who gathered the type as well as numerous other fine collections. The Latinized epithet burgeri means “of Burger.”
NOTES:
1. Philodendron burgeri, as a member of the Philodendron aurantiifolium species-group, is characterized by smallish leaves and horizontally splayed petiole sheaths. It is most easily confused with the largely Mexican Philodendron seguine subsp. seguine, which it most resembles overall, and with the wide-ranging Philodendron aurantiifolium subsp. aurantiifolium, with which it grows in the same areas. From both it differs in its relatively shorter petioles, alveolate leaf surfaces, and relatively shorter female portion of the spadix. In addition, Philodendron seguine has orange (rather than white) fruits, and Philodendron aurantiifolium has shorter peduncles than Philodendron burgeri.
2. The plants typically grow as trunk epiphytes, climbing to at least 10 m and flowering on relatively slender, long-pendent stems.
3. Philodendron schottii subsp. talamancae, though apparently very rare within the range of Philodendron burgeri, also has short petioles and agrees with it in some other details. It differs in having more numerous primary lateral veins, prominent interrupted resin canals on the leaf blade, shorter peduncles, prominent resin canals on the outer surface of the spathe, and a relatively longer female portion of the spadix.
4. A relatively short female spadix portion, the one feature separating Philodendron burgeri from all of these taxa, is often equivalent in subgenus Pteromischum to the presence of an apical sterile male region; yet no obviously differentiated sterile apex is evident in the available material.
5. Found on the Pacific slope of southwestern Costa Rica, from near the Río Grande de Tárcoles to the Golfo Dulce region, and disjunctly on the Azuero Peninsula of central Panama. The single known Panamanian population may be less isolated than it seems, since the species could occur, or once have occurred, in other patches of Tropical Wet Forest on the Pacific slope of western Panama. It is unusual in the subgenus in being nearly restricted to one life zone; the northernmost collection comes from a site mapped as Tropical Moist Forest, presumably from a hygric microhabitat within it. Only two collections are from above 250 m.
6. All fertile collections at or near anthesis are from January to April, mostly February; the two fruiting collections are from April and June. It is one of the few Mesoamerican species of subgenus Pteromischum whose main flowering peak falls in the dry season.
7. The comparison with Philodendron seguine implies white fruits for Philodendron burgeri, whereas the Latin diagnosis calls them cream-colored and a collector’s label “de color crema.”
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Philodendron burgeri
2. Systematic Botany Monographs 47: 188 (1996) — protologue.