AMORPHOPHALLUS GIGAS

Species

PROTOLOGUE:Amorphophallus gigas Teijsm. & Binn., published in Natuurkundig tijdschrift voor Nederlandsch Indië 24: 329 (1862). The protologue is reproduced below.

SYNONYMS:

HOMOTYPIC SYNONYMS: Conophallus gigas (Teijsm. & Binn.) Miq. in Ann. Mus. Bot. Lugduno-Batavi 1: 285 (1864)

HETEROTYPIC SYNONYMS: Amorphophallus brooksii Alderw. in Bull. Jard. Bot. Buitenzorg, sér. 3, 1: 268 (1920)

DISTRIBUTION: Sumatera: Sumatra.

SPECIES DESCRIPTION:

Tuber depressed-globose, reported to weigh to 70 kg, no annual offsets. Leaf solitary; petiole ca. 3–4 m long, ca. 11–20 cm in diam., smooth or rugose near the base, dark green with numerous large and small, rounded or elongate-oval, pale green spots; lamina to 4 m in diam.; leaflets lanceolate, long acuminate, 13–25 cm long, 5–9 cm in diam.

INFLORESCENCE:

Inflorescence long-peduncled, reported to reach to 4.36 m high; peduncle ca. 2–3.5 m long, patterned as petiole; spathe campanulate, erect, broadly ovate, ca. 55–60 cm long, outside dark green changing to pale green, the margin dark red-brown, the base dark olive-green with some obscure ringlike, paler spots, inside pale green with reddish brown spots and reddish veins, margin plicate-sinuous, veins in all parts strongly raised. Spadix longer than spathe, sessile, ca. 150 cm long, emitting a foul stench of decaying meat (the Dutch protologue described it as an unbearable smell of rotting fish) upon flowering.

ECOLOGY:

Found in shady understories

PROPAGATION:

Cuttings taken in November rooted from a low of 0% to a high of 62.5% when taken in early August.

ETYMOLOGY:

From Greek gigas, “giant,” referring to the immense stature of the species, which produces one of the tallest inflorescences in the genus.

NOTES:

1. Amorphophallus gigas ranks as the second bulkiest species in the genus, and certainly the tallest one in flower! It is in most respects very similar to the Javan Amorphophallus decus-silvae (see descr.). Excellent historical photos are seen in Aroideana 4(2): 43, 44, albeit under its synonym Amorphophallus brooksii.

2. Grow in a loose, well-drained but fertile soil. The tuber must not be exposed when dormant. Many growers in the USA did receive seeds of this species from an expedition by the first author together with the late Dr. James Symon. Although many seem to have germinated, an equal number of plants seem to have perished in many places in their second or third year. This may have been caused by using too heavy a soil.

3. Though interesting for its time, the protologue describes an experiment of suspending a thermometer inside the flower, but it failed to register a change in temperature from the surrounding air (tested morning and evening for six days).

4. The experiment above also had two additional interesting findings: they noted that shortly after anthesis, the appendix was covered with liquid, as though coated with heavy dew. The liquid has the same unpleasant smell of rotting fish. They also noted that despite no thermogenesis being observed, pollen was discharged the third day after anthesis, but did not lead to succesfull pollination (assuming no thermogenesis might have not helped bring pollinators in)

5. Phenology of Amorphophallus gigas

According to observations made since February 25th, which were found in a state of bud to wither on March 14th, 2020, the flowering phase of the “bunga bangkai” was 19 days. The life cycle of Amorphophallus titanum consists of several phases, namely the leafy phase (vegetative phase) and the flowering phase (generative phase). Between the two phases, the sleep phase (dormancy phase) is punctuated. The “bunga bangkai” is a compound interest with a spadix type of flower. Solitary inflorescence with short inflorescences. On the end of the cob has a cone (appendix) which is a sterile part

6. At Fairchild Tropical Garden in Miami, Florida, accession FG 941491 was eight seeds of Amorphophallus gigas, received through Don Evans on September 13th, 1993, along with Amorphophallus titanum seed from the expedition of Wilbert Hetterscheid and Dr. James Symon.⁷,⁸

7. Amorphophallus gigas flowered for the first time at Fairchild Tropical Garden in May 1999. Craig M. Allen, the garden's conservatory manager, reported that the inflorescence emerged from the soil around May 1st, from a tuber grown from seed that came with the Amorphophallus titanum seed distributed from the 1993 expedition of James Symon and Wilbert Hetterscheid.⁹

8. According to garden staff, an Amorphophallus gigas inflorescence at Fairchild Tropical Garden began releasing a strong odor on May 28th, 1999, and had opened fully by May 29th. On May 31st it stood 132 inches (about 335 cm) tall, from a tuber that weighed only 4.5 pounds (about 2 kg).¹⁰

9. On April 28th, 2003, Craig M. Allen, the garden's conservatory manager, saw flies all over the top of the spadix of flowering Amorphophallus gigas at Fairchild Tropical Garden, in the Amorphophallus display area, where there was a hole in the screen.¹¹ On May 9th, 2003, he noted developing berries on one of the first Amorphophallus gigas to bloom, although the garden had not pollinated it.¹² The pollen source is unknown, and no seed outcome was reported.

HYBRIDS: