SYNGONIUM RAYI
PROTOLOGUE: Syngonium rayi , published in Phytologia 82: 53 (1997).
Syngonium rayi Croat & Grayum, sp. nov. Species aspectu cum Syngonio oduberi T. Ray optime congruens, sed differt petiolis lobis laminaribus posticis relative longioribus. Type: CULTIVATED. Grown at Selby Gardens [originally collected at La Selva Biological Station, Prov. Heredia, Costa Rica, in early October 1985 (J.T. Atwood s.n.)], 30 May 1990, H. Luther s.n. (holotype: INB; isotypes: MO, PMA, SEL).
DISTRIBUTION: Costa Rica to Panama: Costa Rica, Panama.
DISTRIBUTION NOTE: Costa Rica: Alajuela, Guanacaste, Heredia, Limón, San José Panama: Panamá Province.
SPECIES DESCRIPTION:
Nomadic vine to 2–3 m; scandent climber, fertile ca. 2–3 m above the ground; internodes moderately elongated, drying 1–4 cm long, 3–7 mm diam., yellowish brown to grayish brown, moderately ridged, semiglossy; petioles (3.6)8.4–22.5 cm long, sheathed for ca. 58–94% their total length, matte, finely ribbed; sheath involute, weakly free-ending at apex, free part drying sharply and deeply sulcate; blades simple, (5)10–25 cm long, (2.5)3.5–13.0 cm wide, 1.7–2.0(3.6) times longer than broad, ovate, oblong-ovate or oblong-deltate to narrowly ovate-sagittate, elliptical, lanceolate-oblong or lanceolate, cordate or hastate at base, dark green to purplish and matte to velvety above, moderately paler and weakly glossy below, margin minutely undulate; anterior lobe broadest in middle, often inequilateral with one side more broadly rounded (the other side more nearly straight), weakly constricted at petiolar plexus; posterior lobes (2)3–4(7) cm long, (1.5)2.6–2.8(4.0) cm wide; sinus narrow, broadened only at apex owing to the prominently in-turned posterior lobes; basal veins 5 or 6 pairs, 1st & 2nd pairs free to base; 3rd pair fused 2–4 mm; 5th pair fused 7–17 mm; primary lateral veins (3)4–11 per side; tertiary and collective veins prominulous below.⁴
INFLORESCENCE:
Inflorescence 1–4 per axil; peduncle ca. 2.2–5.2 cm long, oval in cross-section, 6–7 x 5–6 mm wide; spathe 10.5–14 cm long; tube 4.5–6 cm long, 2–2.7 cm wide, dark green, matte outside, dark purple-violet, glossy inside; spathe blade 6.5–7.5 cm long, opening to 3 cm wide, creamy yellow outside, creamy white to wine-red inside; spadix (6.0)8.1–9.5 cm long; 0.4–0.7 cm diam.; staminate portion creamy white, 7.5–8.0 cm, 1.1 x 1.25 cm diam., constricted area 1 cm long, 6 mm diam.; sterile male section 2.3 cm long, the basal portion 1.5 cm long, 1 cm diam.; pistillate portion pale green, 9 mm long in rear, 1.6 cm long in front. Infructescences to 6 cm long, 3 cm diam., the spathe green outside, red inside. Flowering May-July (December), mature fruits May & December. An indication of bimodal flowering.⁴
ECOLOGY:
Syngonium rayi ranges from Costa Rica (Fila Costeña, Cordillera de Guanacaste, Atlantic slope of Cordillera de Tilarán and Central, Barra del Colorado region) to eastern Panama (Cerro Jefe, Kunayala); 0–1000 (1500 m), occurring in Tropical wet forest life zone in Costa Rica and a Premontane rain forest life zone in Panama.⁴
ETYMOLOGY:
Named for Thomas S. Ray, who recognized the species as new during his doctoral research at the La Selva Biological Station in the 1970s, who contributed significantly to the understanding of Syngonium and Araceae in general, and who is well respected for his conservation work in the Sarapiquí region.² Croat later dedicated his 2023 revision to him.⁴ The type was grown from material collected at La Selva Biological Station, where Ray had worked.²
NOTES:
1. The species is a member of section Cordata and is characterized by its long slender internodes, petioles sheathed for ca. 50–95% their total length, the sheath weakly free-ending at apex, free part sharply and deeply sulcate, by its simple gradually acuminate blades with convex margins and short spreading, moderately acute posterior lobes, the anterior lobe broadest in middle and often inequilateral, a narrow sinus, 5 or 6 pairs of basal veins, (3)4–11 primary lateral veins per side as well as 1–4 inflorescences per axil with the spathe tube oblong-elliptic and green outside, dark purple-violet inside, the spadix with the pistillate portion pale green and the infructescence with the spathe tube red inside. Syngonium rayi can be confused with Syngonium oduberi from the Osa Peninsula but that species differs by having only small, narrowly rounded posterior lobes which are not at all directed outward. Grayum (1997) reports that the species is rare in the wild and that at the type locality in the La Selva Biological Station fruiting specimens were never observed despite the presence of many juvenile specimens in the region.⁴
STORY:
STORY TITLE: Named for the man who called climbing aroids the primates of the plant kingdom
Thomas S. Ray came to Syngonium through its habit rather than its flowers. His Harvard doctorate of 1981 was on the growth and heterophylly of the genus, and from 1974 to 1989 he worked in the lowland rain forests of northern Costa Rica, first at La Selva and after 1982 at Finca El Bejuco, a property he bought and ran himself. He studied the foraging behavior of aroid vines, which he considered the "primates of the plant kingdom." When Croat revised the Central American species in 2023 he dedicated the work to Ray, crediting his interest in the genus and his discovery of new and interesting species with drawing Croat into it in the first place.⁴
Ray's 1992 paper on foraging in climbing aroids explains what he meant. A climbing aroid grows "like a leafy snake moving through the forest": only the growing tip moves, the stem behind it slowly dies, and every leaf must survive wherever it happened to be made. He sorted shoots into four forms by the shape of their internodes, from acaulescent rosettes to flagellar shoots whose internodes are thirty or more times as long as wide, and showed that a single plant switches between them as its surroundings change. His demonstration species was Syngonium triphyllum. When the palm trunk supporting one shoot was cut, the shoot switched to its flagellar form, its internodes narrowing to 4.2 mm and lengthening to 20.8 cm, and switched straight back to climbing form when trained onto another tree. Flagellar shoots are skototropic: they steer toward darkness, which in a forest means a trunk.⁵
The species that carries his name was described in 1997 by Michael Grayum and Croat from a plant grown at the Marie Selby Botanical Gardens from material collected at La Selva in October 1985; Ray's own collections from Finca El Bejuco are among the specimens cited.² Asked about it on the Aroid-L list in 2006, Croat placed it near La Selva by Puerto Viejo in the Tropical wet forest life zone, and added that he knew of no Syngonium that is not a hemiepiphyte.⁶
Ray left the rain forest for digital evolution, creating in the 1990s what is regarded as the first compelling example of artificial life, and later turned to the chemistry of the human mind.⁴
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Syngonium rayi
2. Phytologia 82: 53 (1997) — protologue.
3. iNaturalist: Syngonium rayi
6. Croat, T.B. 2006. Re: Syngonium rayii. Aroid-L, 30 October 2006
Additional photos from iNaturalist by njweess, nickrope and Ocean Fleskes