PHILODENDRON CROATII

PROTOLOGUE: Philodendron croatii , published in Systematic Botany Monographs 47: 168 (1996).

Philodendron croatii Grayum, sp. nov.

Differt a Philodendron rigidifolio laminis foliorum inaequilaterioribus nervis secundariis utroque latere numerosioribus, pedunculis brevioribus, spadice breviore segmento femineo relative longiore floribus femineis minoribus, a Philodendron tuerckheimii vaginis petiolorum erectis involutisve, laminis foliorum magis coriaceis latioribus nervis secundariis numerosioribus.

Type: Panama. Panamá: Cerro Campana, 850 m, 11 Mar 1973, Liesner 630 (holotype: MO-2199000!; isotype: US!).

DISTRIBUTION: Panama to NW. Colombia: Colombia, Panama.

SPECIES DESCRIPTION:

Rigidly scandent vine climbing in trees to at least 3 m. Internodes 0.5–10.0 cm long, 0.55–0.80 cm wide, dark green to dark brown or blackish, weakly glossy, sparsely thick-short-lineate (Croat 35993), drying mid- to dark brown and coarsely sulcate; roots rare at distal nodes, abundant when present (on juvenile stems), to ca. 1.0 mm in diameter. Petiole (5.3–) 6.5–12.5 cm long, P/L=(0.35–) 0.42–0.62, extensively sheathed, the sheath erect-spreading to involute, the free portion prolonged by 0.4–1.1 (–1.3) cm; unsheathed portion of petiole obsolete or to ca. 0.35 (–0.80) cm long. Lamina (13.4–) 15.6–23.5 (–25.8) cm long, (5.6–) 10.7–15.3 cm wide, L/W=(1.29–) 1.44–1.89 (–2.67), IQI=3–7 (–9), thinly coriaceous to ± coriaceous, semiglossy above, semiglossy to glossy below, moderately bicolored, ovate to broadly ovate or elliptical (rarely obovate), gibbous (broadest toward the base or occasionally near the middle, rarely above), ± abruptly short-acuminate apically (the acumen ca. 0.6–1.3 cm long), moderately to broadly cuneate or rounded basally; midrib convex below; primary lateral veins (7–) 9–15 per side, 0.5–3.8 cm apart, convex below; minor veins visible below; abaxial laminar surface drying virtually smooth, with the reticulate veins not evident (except occasionally near margins); white stitching remote to abundant; resin canals usually visible closely flanking the primary veins, and interrupted canals conspicuous mainly in the distal and marginal portions of the lamina; adaxial surface virtually smooth to (more typically) sparsely or moderately granular, mainly along the major veins, with reticulate veins only toward the margins; white stitching absent (rarely) to remote or occasional; resin canals not evident.

INFLORESCENCE:

Inflorescences solitary; cataphylls absent; peduncle 1.1–2.0 cm long, P/S=ca. 0.09–0.17; spathe at anthesis 14.5–15.0 cm long, 2.0–2.9 cm wide, externally pale green or greenish white below and densely white-lineate, whitish distally, internally white; spathe drying virtually smooth to (more usually) densely low-granular externally, with white stitching absent except at the margins (or, sometimes abundantly, toward the base) and abundant, interrupted resinous streaks extending onto the peduncle, internally densely granular, with longitudinal secretory striations extending virtually to the apex; acumen of spathe 0.4–0.5 cm long. Stipe of spadix 0.4–1.0 (–1.2) cm long; spadix (9.0–) 10.2–12.5 cm long, the fertile male portion 0.8–1.2 cm wide (thickest toward middle), white; sterile male zone 0.40–0.55 cm long; fertile female portion of spadix (2.5–) 2.9–4.1 (–5.6?) cm long (to 9.0+ cm in fruit), F/S=ca. 0.27–0.48, (0.95–) 1.05–1.30 (–1.55?) cm wide (to 3.3+ cm in fruit), green; fertile male flowers 1.3–1.5 mm long, 0.5–1.8 mm wide, irregularly polygonal, columnar; sterile male flowers 1.2–1.5 (–1.9) mm long, 0.7–1.3 mm wide, ± columnar to anvil-shaped; female flowers 1.50–1.55 mm long, 0.7–1.2 mm wide, the stylar canals not countable. Ripe fruits not described. Seeds (Luteyn & Kennedy 1663) 1.0–1.1 mm long, 0.20–0.25 mm wide, straight to ± curved, finely striate with the striae virtually smooth, drying orangey brown and glossy.

ECOLOGY:

Found as a vine climbing in trees, principally in Tropical Wet Forest, but also in Tropical Moist Forest and (perhaps) Premontane Rain Forest life zones; (150–) 400–900 (–1500?) m.

ETYMOLOGY:

Named in honor of Thomas B. Croat of the Missouri Botanical Garden, a leading authority on and the most prolific collector of neotropical Araceae, who discovered the species near El Valle de Antón, Coclé Province, Panama, on 13 April 1971. The Latinized epithet croatii means “of Croat.”

NOTES:

1. Philodendron croatii is recognized by its dark brown or blackish stems, which are sharply sulcate when dry, its erect-spreading to involute, more or less indurate petiole sheaths, and its ovate to broadly elliptical, somewhat coriaceous leaf blades that dry reddish. Relative to Philodendron rigidifolium it has more strongly inequilateral blades with more primary lateral veins on each side and more or less conspicuous abaxial resin canals, shorter peduncles, significantly smaller inflorescences with a proportionately longer female portion, and much smaller female flowers. Relative to Philodendron tuerckheimii it has erect or involute rather than horizontally splayed petiole sheaths, more coriaceous and broader leaves with more numerous primary lateral veins, and thicker spadices.

2. The species is morphologically somewhat intermediate between Philodendron rigidifolium and Philodendron tuerckheimii. Its erect to involute, indurate, distally free petiole sheaths and subcoriaceous leaf blades strongly suggest Philodendron rigidifolium, and sterile specimens of the two may be difficult to distinguish.

3. It resembles Philodendron tuerckheimii in its blackish stems, leaf epidermal micromorphology (conspicuous abaxial resin ducts), inflorescence size and structure (relatively long female spadix portion), and flower size. Philodendron croatii also has longer petioles and leaf blades than Philodendron tuerckheimii, although some aberrant Panamanian material provisionally placed in Philodendron tuerckheimii has petioles and blades as long as those of Philodendron croatii.

4. The few available collections suggest local differentiation, as expected in such isolated populations: those from the El Valle region have relatively shorter petioles and more strongly inequilateral leaves than those from Cerro Campana or Santa Rita Ridge, though material from these three sites is reasonably uniform overall.

5. One collection from the Colombian border in the region of Cerro Tacarcuna stands well apart and is only tentatively assigned to the species. It lies far east of the main range, at a higher elevation (1300–1500 m) and in a different life zone (Premontane Rain Forest), and has shorter petioles, smaller, narrower, more markedly inequilateral leaf blades with fewer (ca. 7) primary lateral veins, different epidermal micromorphology (resin ducts not evident abaxially), and apparently smaller inflorescences, though these may not be fully mature. This population may merit taxonomic recognition, perhaps as a subspecies, once more collections are available.

6. Spottily distributed in central and eastern Panama. Flowering specimens have been collected from March to July, except the aberrant Cerro Tacarcuna specimen, collected in October; the only specimen with fully ripe fruit was collected in August.

REFERENCES:

1. Plants of the World Online, Royal Botanic Gardens, Kew — Philodendron croatii

2. Systematic Botany Monographs 47: 168 (1996) — protologue.

3. iNaturalist: Philodendron croatii

Additional photos from iNaturalist by Oliver Ingold