Dieffenbachia tonduzii Croat & Grayum

Terrestrial herb 0.5–1.5 m tall, usually to less than 1 m tall; internodes usually solid dark to medium green, sometimes faintly marbled with gray-green or yellowish gray throughout (on plants which also have streaked petioles), initially weakly glossy, becoming semiglossy to glossy, often with a subvelvety sheen, 1.5–4.5(-6) cm long, 1.5–3 (-4.5) cm diam, the petiole scars manila to whitish, curved downward on the opposite side of the stem and ending unevenly; petioles 10–24 cm long (averaging 17.6 cm long), held more or less erect, medium green (except sometimes white to pale green at base), almost matte to weakly glossy, weakly striate (especially near the base), narrowly rounded to obtusely angular on abaxial surface and often whitish medially, sometimes streaked in a variegated pattern throughout (this whitish coloration continuing onto the midrib), sheathed virtually throughout; sheath erect to involute (rolled inward throughout in age), free-ending and unequally rounded at apex, prolonged to 2 cm beyond the base of blade; unsheathed part obsolete or rarely to 1 cm long (when evident obtusely flattened); blades inequilateral (one side 1–3.0 cm wider), ovate to ovate-elliptic or oblanceolate-elliptic, (15-)25–48(-63) cm long, (8-)15–32 cm wide, (averaging 34 x 16 cm), broadest near the middle, sometimes below, frequently above the middle, 1.4–2.5(-3.5) times longer than wide (averaging 2.1 times longer than wide), 1.9–3 times longer than petioles, spreading to erect-spreading, gradually to abruptly acuminate, sometimes acute at apex, inequilaterally cordulate at base, one side sometimes broadly rounded to obtuse, the other side cordulate, sometimes inequilaterally acute, subcoriaceous, often conspicuously quilted, moderately bicolorous; upper surface usually solid dark to medium green, sometimes conspicuously to sparsely variegated with pale green or pale yellow throughout much of the surface, the mottling large or small, but somewhat restricted to the area midway between the midrib and margin, matte to weakly glossy, sometimes appearing weakly velvety, drying gray-green to olive-green or dark brown; lower surface much paler and matte to weakly glossy, silvery-green, drying yellowish green to yellow-brown below; midrib flat to broadly rounded and moderately to strongly paler, pale green or sometimes creamy white above (sometimes only toward the apex), bluntly acute to obtusely angular and paler, sometimes whitish or creamy white below, (0.6-)1–1.7 cm wide; primary lateral veins (14-)18–25(-30) per side, arising at an acute angle with the midrib and spreading at 45–90 degrees, sometimes reflexed toward the base, prominently to weakly and obtusely sunken above, convex to weakly raised and darker than surface or concolorous below, some of the lowermost with a weak fold near the base (Croat & Grayum 60112), sometimes convex-pleated below; interprimary veins almost as conspicuous as the primaries; minor veins moderately to distinctly visible, darker than surface below. Inflorescences 1–2(-4) per axil, often with two oriented in opposite directions; peduncle (1-)6–17 cm long (averaging 10.3 cm long), 7–8 mm diam, weakly glossy, dark to medium green, sometimes with pale yellow-green streaks; spathe (12-)15–28 cm long, (averaging 20 cm long), 2–4 times as long as peduncle, acuminate at apex, convolute to about the middle in lower part, matte to weakly glossy outside, glossy within, solid medium green on both surfaces, gradually and weakly constricted somewhat above the middle; spathe tube 1.5–30 cm diam when closed, 6.8–9 cm wide when flattened; constricted area 4.3–4.5 cm wide flattened spadix (9-)16.5–25.5 cm long, about as long as or up to 3.0 cm shorter than the spathe; free portion 7.8–8.5 cm long; pistillate portion (4.8-)6–11.5 cm long; mostly sterile portion sparsely flowered to naked (rarely lacking, as in Croat 70768), 1.8–4.0(-8.5) cm long with 0.6–1.5 cm totally bare, the uppermost portion with a few staminodia, sometimes with a few scattered staminodia throughout, the lower half sometimes with an occasional pistil and much reduced staminodia, rarely with the female flowers more or less equidistant and nearly contiguous with staminate part; fertile staminate portion (4-)5.5–10 cm long, 7–10 mm diam, slightly broader midway, weakly tapering to apex and base, bluntly pointed at apex; male flowers 5–6 per spiral, more or less rounded in outline, crenulate along margins, truncate at apex; sterile male flowers irregularly shaped, 1.8–2.5 mm diam; pistillate portion of spadix to 11 cm long, 9–10 mm diam; female flowers, (15-)48–62, closely aggregated except in the upper 1.5 cm of spadix, 4–5 in the width of the spadix (uppermost pistil borne on an almost bare segment of the spadix); pistils pale cream-yellowish to pale yellow-green, smooth, 2.3–3.5 mm diam; style (after stigma has fallen) sharply cupuliform, 1.5–1.7 mm diam, with a single central pore, stigmas yellow; staminodia clavate, white, 2–3 mm long, mostly contiguous and sometimes fused at base; fruiting spathe pale yellow; berries red to red-orange, 5–8 mm diam.

Dieffenbachia tonduzii ranges from SE Nicaragua to the Pacific slope of Colombia (Antioquia, Chocó, Cauca, Valle) and Ecuador (Esmeraldas and Los Ríos), from sea level to 1400 m, in tropical wet forest and premontane wet forest life zones. The species is characterized by its fully sheathed petioles, usually matte to weakly glossy, sometimes weakly velvety blades with cordulate bases and numerous, broadly spreading primary lateral veins. Dieffenbachia tonduzii is polymorphic with regard to leaf markings in the same way as D. oerstedii, and is quite variable in all respects. The species is similar to D. daguensis Engl., a Colombian species described from less than 200 m elevation on the Río Dagua in Valle Department. That species also has many rather close primary lateral veins and a fully sheathed petiole, but differs in having the staminate and pistillate sections of the spadix contiguous or nearly so. In addition, it differs in having much shorter petioles (described as being up to 5 cm long) A South American species, D. parlatorei Linden & André, also sometimes has petioles fully sheathed but differs from D. tonduzii in having leaf blades usually broadest above the middle, semiglossy on the lower surface, and the midrib often broadly rounded and spongy. It also has the primary lateral veins arising at 40--60 angle from the midrib (versus often at more than 60 degrees and sometimes up to 90 degrees in D. tonduzii).