AMORPHOPHALLUS OCHROLEUCUS

PROTOLOGUE: Amorphophallus ochroleucus Hett. & V.D.Nguyen, published in Blumea 46: 265 (2001).

Amorphophallus ochroleucus Hett. & V.D. Nguyen, spec. nov. Amorphophallo albo similis, inflorescentia juxta folium evoluta, foliis bulbillis intercalaribus gaudentibus differt. - Typus: Hetterscheid H.AM.927-T (holo L, spirit coll., flowering 22 February 1998), Vietnam, Gia Lai prov., K'bang distr. (coll. from a plant cultivated in the Leiden Bot. Garden; orig. coll. Averyanov 4747).

DISTRIBUTION: Vietnam: Vietnam.

DISTRIBUTION NOTE: Vietnam: Gia Lai Province - K'bang District (the type) and Cha Lo.².

SPECIES DESCRIPTION:

Tuber depressed globose, to 15 cm diam., to 10 cm high, no offset development. Petiole 40-60 cm long, 2-3 cm diam., turgid, smooth, bright green with numerous, blackish or very dark reddish purple, small, irregular or elliptic or rounded spots; lamina to c. 120 cm diam., rachises unwinged; leaflets distant, the most proximal ones short petiolulate, elliptic to elongate elliptic, leathery, to 26 cm long, to 7 cm diam., acuminate.²

INFLORESCENCE:

Inflorescence simultaneous with leaf but appearing several months later, long peduncled; peduncle 18-21 cm long, 0.8-1 cm diam., yellowish green, otherwise spotted as petiole; spathe erect, elongate ovate, 11-17 cm long, 9-10 cm diam., acute, base and limb hardly differentiated, outside pale dirty yellowish or pinkish, with very indistinct greenish flushes and scattered dark reddish brown or blackish dots, often concentrated around the midrib and near the base and there confluent to form narrow bands lengthwise or patches, the margin very faintly flushed with pinkish purple, inside as outside but unspotted, or only a few blackish spots near the top, base within densely but very shallowly rugulose. Spadix sessile, slightly longer than the spathe, 12-23 cm long; female zone cylindric or slightly obconic, 2 cm long, 1.5-2.5 cm diam., terete or slightly dorsoventrally compressed; male zone cylindric or slightly conic, dorsoventrally compressed, 4-8 cm long, 1.2-3 cm diam., flowers congested; sterile zone between female and male zone thickened, slightly conical, base truncate, 0.6-1.2 cm long, 1.4-3 cm diam., staminodes congested; appendix fusiform-conical, dorsoventrally compressed, 5-11 cm long, 1.4-3 cm diam. slightly above the base, obtuse, surface smooth with scattered, very shallow depressions, white, producing a strong gaseous smell during female anthesis. Ovaries angulate, 3 mm diam., 1.8 mm high, bilocular, pale green; style conical, 1 mm long, 1.2 mm diam. at the base, 0.8 mm diam. at the top, yellowish white; stigma subglobose or depressed, 2 mm diam., 1-1.5 mm high, sinuously bilobed or very shallowly bilobed, surface densely verruculate, off-white or pale yellow, lobes and sinuses obtuse, shallow. Male flowers consisting of 4 or 5 stamens; stamens 2 mm long; filaments 1 mm long, basally connate, off-white; anthers 1-2 mm diam., 1 mm long, truncated, off-white; pores apical, near the margin, slit-like when closed, oval when open, connective broad; pollen reticulate, ellipsoidal (length/breadth 1.50), 60 µm long. Staminodes rhombic, flat, to c. 5 mm diam., off-white.²

PROPAGATION:

Results with cuttings of this late-emerging species ranged from 0% in early February to 70% in mid-October. This should be a very easy species to root in mid-summer.

ETYMOLOGY:

From Greek ōkhros, “pale yellow,” and leukos, “white”: the epithet refers to the whitish-yellowish colour of the spathe of the type plant.²

NOTES:

1. Diagnosis: similar to Amorphophallus albus, but differing in the inflorescence developing alongside the leaf, and in the leaves bearing intercalary bulbils.²

2. Amorphophallus ochroleucus is morphologically similar to a group of mainly mainland-Asian species that includes Amorphophallus krausei of Myanmar, Thailand and Yunnan, Amorphophallus albus of Yunnan, and Amorphophallus salmoneus of Palawan; all share the general spathe and spadix form. It is unique within that group in flowering at the same time as the leaf, and unique in the whole genus in having distinctly reticulate pollen. It further differs from Amorphophallus krausei and Amorphophallus albus in its much larger stigmas, from Amorphophallus salmoneus in its almost smooth staminodes and smooth appendix, from Amorphophallus krausei in its bilocular ovaries, and from Amorphophallus albus in its much shorter style, apical stigma and functionally bilocular ovaries.²

3. The inflorescence appears together with the leaf but several months later, and the appendix gives off a strong gaseous smell during female anthesis.²

REFERENCES:

1. Plants of the World Online, Royal Botanic Gardens, Kew — Amorphophallus ochroleucus Hett. & V.D.Nguyen

2. Blumea 46: 265 (2001) — protologue.

3. Alan Galloway — Amorphophallus ochroleucus, alangallowaybotanicals.com.

4. Propagation of Amorphophallus by Leaf Petiole Cuttings — Juniper Level Botanic Garden