Volume 11 > Part 2 > Year 2012 > Page 159 > Araceae > Amorphophallus

28. Amorphophallus longituberosus (Engl.) Engl. & Gehrm.

in Engl., Pflanzenr. IV, 23C (Heft 48): 73, Fig. 26. 1911; Gagnep. In Lecomte, Fl. Indo-Chine 6: 1167. 1942.— Hydrosme longituberosa Engl., Bot. Tidsskr. 24: 273. 1902. Plate XXVI: A–B.

Accepted Name : This is currently accepted.

Synonyms & Citations :

Description : Tuber elongate, moderately branched at maturity, off-white, turning grey or blackish brown at exposure, 5–25 cm long, apically 2–7.5 cm in diam. Leaf solitary; petiole 10–120 by 0.5–2.5 cm (base), smooth, often with a whitish waxy coating, ground colour dirty pale or mid grey, pale pinkish, or pale green covered to various extents with dark grey or dark blackish green oval or narrowly elongate spots and/or stripes, the last often running the entire length of the petiole; leaf blade highly dissected or moderately so, 30–120 cm diam., rachises winged all over; central main segment without major branching; leaflets elliptic, elliptic-lanceolate, lanceolate or linear-lanceolate, 6–26 by 1–5 cm, short or long acuminate, base decurrent, slightly succulent, main veins impressed, adaxially green, abaxially pale green. Inflorescence solitary, long pedunculate; peduncle appearance as petiole, 10–90 by 0.8–1.5 cm (base); spathe erect, elliptic to elongate triangular, 4–22 by 2–12 cm, acute, apex hooded or nearly so, base convolute, widening at staminate anthesis, base interior nearly smooth, with few, scattered, shallow warts or densely covered with tiny, punctiform warts or moderately to densely covered with fleshy, elongate, variously branched warts, exterior pale grey with several rounded or broad, elongate, dark grey spots/stripes and small white dots or uniformly green or greenish white with a few small white spots and/or some maroon streaks and a reddish or violet margin, interior entirely dirty greyish white or pale green, sometimes the upper part flushed with violet, with a darker green or pale to dark maroon base, margin sometimes flushed with greyish purple; spadix sessile, slightly or distinctly shorter than spathe, 3–15.5 cm long; pistillate flower zone cylindrical or slightly obconical, 0.5–2.5 by 0.5–1.5 cm, flowers congested or slightly distant; ovaries depressed, circular or diamond-shaped in cross-section, 1–1.3 by 2–5 mm, pale green, 2-, 3-, or 4-locular, one basal ovule/locule; style 0.2–2 mm long, greenish or off-white; stigma capitate, oval, triangular, subcircular or circular in cross-section, 1–2.3 mm, margin often reflexed, shallowly or distinctly 2-, 3- or 4-lobed, surface minutely echinate, orange, pale yellow or whitish, lobes hemispherical or conical; staminate flower zone slightly or more distinctly conical, occasionally fusiform, 1–5.5 by 0.5–1.8 cm, flowers congested, fused to one basal layer with superficial anthers upwards; staminate flowers consisting of 3–6 stamens; stamens 2.5–3 mm long, off-white or pale orange-yellow; filaments 1.5–2 mm long, entirely connate forming a thick column being distinctly enlarged in the lowermost flowers and mostly pushing the anthers to a marginal position, adaxially truncate and with shallow grooves separating the anthers; anthers subglobose, 1 by 1.3 mm, occasionally reduced in the lowermost flowers, connective large, massive, often high, sometimes producing one or two tiny, clear yellowish brown droplets during pistillate anthesis, sometimes all connectives in one flower radiating from the centre of the column, partly or entirely separating the pores and thickened towards the outer end; pores elongate, lateral, margins occasionally reddish brown, sometimes confluent through incomplete separation by the connective; appendix cylindrical to conical, 2–7.5 by 0.6–2.2 cm, apex obtuse, base sometimes with a few rounded thick staminodes intermediate between stamens and appendix wall, smooth, moderately glossy, ivory-white or pale purplish grey, warm at pistillate anthesis and producing a distinct scent of anise. Infructescence cylindrical, 2–8 cm long with a few or many berries; fruits elliptic or rounded, ca 1 cm long, 1-, 2-, 3-, or 4-seeded, at first green, ripening red. Seeds ca 7 mm long, testa pale brown with small, black spots, germinating even in the berries.

Thailand : NORTHERN: Chiang Mai, Lampang, Tak, Phitsanulok; NORTH-EASTERN: Udon Thani, Khon Kaen; SOUTH-WESTERN: Kanchanaburi, Prachuap Khiri Khan; CENTRAL: Saraburi; SOUTH-EASTERN: Chaiyaphum, Sa Kaeo, Chon Buri, Chanthaburi, Trat (type: Schmidt 541, holotype -C); PENINSULAR: Surat Thani, Krabi, Satun.

Distribution : Peninsular Malaysia (type of Amorphophallus viridis).

Ecology : Shaded or open places in evergreen or deciduous forests, in dry dipterocarp or diperocarp-oak forests, in scree, on sandy or rocky poor ground, on limestone or shale or granite; to 600 m alt.

Vernacular : Buk hua yao (บุกหัวยาว)(Southwestern); i-lok-noi (อีลอกน้อย)(Sa Kaeo).

Notes: Amorphophallus longituberosus most closely resembles A. albispathus, A. purpurascens, A. chlorospathus, A. tenuispadix and A. angustispathus Hett. (Myanmar) which have similar inflorescences but all five have apical pores. In addition, both A. tenuispadix and A. purpurascens possess globose tubers. Amorphophlallus angustispathus has a spadix longer than the spathe and very different staminate flowers.

The staminate flowers are free in the lower part of the staminate flower zone but entirely fused in the upper part, the columns forming a thick layer on which the anthers are placed. This layer continues apically without interruption as the outer wall of the appendix. The epidermal layer of the appendix is a continuation of the epidermis of the connectives. The hollow centre clothed with a layer of very loose tissue is continued partly downwards into the staminate part of the spadix. Thus, it seems clear that the outer appendix wall is serially homologous to the somatic tissue of the staminate flowers.

The leaves of Amorphophallus longituberosus are of two distinct types, either relatively short petioled and with few, large, elliptic leaflets (to 26 by 9 cm), or relatively long petioled with numerous small, linear-lanceolate (e.g. 14 by 1 cm) to elliptic leaflets.

Engler (1902: 274) did not cite the number of the type-collection in the protologue but did so in his Pflanzenreich treatment (1911: 73; “Schmidt 541”) where he said the material was at B and C. I have been unable to locate a Schmidt specimen at C. The B specimen has no field data. It is annotated by Engler and is the basis for his drawing in the Pflanzenreich (1911: Fig. 26).