SYNGONIUM LLANOENSE
PROTOLOGUE: Syngonium llanoense , published in Annals of the Missouri Botanical Garden 68: 585 (1982).
Syngonium llanoense Croat, sp. nov. Caudex haud glaucus, ca. 2 cm diam.; foliorum petiolus 9–27 cm longus, ad apicem vaginatus; lamina oblongata-elliptica, 18–28 cm longa, 8–11 cm lata, apice acuminata, basi rotundata ad subcordata. Inflorescentia usque 2 in axilla; spathae tubus 5–6 cm longus, ca. 3 cm latus, viridis; spathae lamina e viridi alba, ca. 10 cm longa; spadix 11.5 cm longa; parte mascula spadicis ca. 9.5 cm longa, alba, parte feminea spadicis viridi, 2 cm longa, basi 9 mm diam., apice 6 mm diam. (in sicco). Type: Panama, Canal Zone, Summit Gardens (no doubt collected originally in Panamá or Colón Province), Croat 17148 (MO-219002, holotype).
DISTRIBUTION: Panama to W. Colombia: Colombia, Panama.
DISTRIBUTION NOTE: Panama: Colón (Panama), Panamá Province.
SPECIES DESCRIPTION:
Nomadic vine; juvenile plants with trailing stems, leaves much like those of adult but smaller; stems medium green when young, becoming dark olive-green to purplish; internodes 3–6 cm long, to 6 mm wide, weakly sulcate above petioles in lower part of internode; petioles 6 cm or longer, sheathed nearly throughout; sheath 1.0–1.3 cm wide when flattened. Adult plants with stems closely appressed to trees, dark olive-green, shiny, to ca. 2 cm diam., becoming brown in age, drying with longitudinal wrinkles; internodes to 5 cm or more long on lower parts of stem, 1–3 cm near apex; sap pale tan. Leaves persisting on upper 1 m or more of stem; petioles 9–33 cm long, broadly sheathed almost throughout, broadly canaliculate from end of sheath to blade, sheath 2–3 cm wide when flattened (to 5 cm wide when subtending an inflorescence), margins of sheath erect at base, broadly spreading toward apex, free-ending and emarginate at apex (with apical lobes sometimes extending beyond bottom of blade); blades simple, oblong- elliptic to ovate-elliptic, 13–34 cm long, 6–13 cm wide, gradually acuminate and turned down at apex (acumen apiculate), narrowly rounded to subcordate at base, posterior lobes 1–2 cm long, held almost erect, rounded at apex, upper surface medium green, matte to semiglossy, lower surface much paler, matte; midrib prominently sunken; primary lateral veins 10–18 per side, sunken above, raised beneath; interprimary veins few; tertiary veins distinctly visible; principal collective vein weakly sunken, 4–8 mm from margin, weakly loop-connected between primary veins.³
INFLORESCENCE:
Inflorescences usually 2 per axil, erect at anthesis; prophylls ca. 20 cm long; peduncle 6–8 cm long, epidermis in part becoming inflated on drying; spathe 15–16 cm long; spathe tube green, ovoid-ellipsoid, 5–6 cm long, ca. 3 cm diam.; spathe blade greenish white, ca. 10 cm long, acuminate at apex; spadix 11.5 cm long (on dried specimens); pistillate portion of spadix green, ca. 2 cm long, ca. 9 mm diam. at base, ca. 6 mm diam. at apex; staminate and sterile portions of spadix 9.5 cm long, white, sterile staminate portion ca. 12 mm diam., staminate flowers mostly ca. 2 mm diam., sterile flowers mostly 4–5 mm diam. Infructescences pendent; peduncles green, weakly flattened, to 10 cm long, fruiting spathe oblong-elliptic, 8–10 cm long, 3.0–4.5 cm diam., syncarp subglobose, ca. 5 cm long, 4 cm diam., tan-cream; seeds subglobose, ca. 8 mm diam. Flowering inflorescences have been seen in June and fruits have been found in June, July and October.³
ECOLOGY:
Syngonium llanoense is endemic to Panama and occurs naturally only in Tropical wet forest life zones, ca. 50–550 m.³ altitude: 50–550 m
ETYMOLOGY:
Named for El Llano, the settlement at the start of the El Llano–Cartí road in Panamá Province, Panama, along which the species was collected. The Latinized ending-ense means "from that place." Croat's description does not spell the allusion out.²
NOTES:
1. The species is a member of section Cordata, It is unique among known members of the genus in having oblong-elliptic leaves and a fully sheathed petiole. In the key the species may track to Syngonium castroi from Costa Rica which differs by having a narrower sheath, less than 1 cm wide in contrast to having a sheath 2–3 cm wide.³
2. Type species of Croat's 1981 section Oblongata, which was merged into section Cordata in 2023 once new species had blurred the line between oblong and cordate blades.³
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Syngonium llanoense
2. Annals of the Missouri Botanical Garden 68: 585 (1982) — protologue.