AMORPHOPHALLUS INTERRUPTUS
PROTOLOGUE:Amorphophallus interruptus Engl. & Gehrm., published in Pflanzenr., IV, 23C: 90 (1911). The protologue is reproduced below.
DISTRIBUTION: N. Vietnam: Vietnam.
SPECIES DESCRIPTION:
Tuber depressed-globose, about 1.5 cm in diameter. Leaf petiole smooth; blade trisect, the primary segments 20–40 cm long and dichotomously divided; secondary segments pinnatisect; ultimate segments alternate, lanceolate, oblong, or even obovate, acuminate-acute, 7–20 cm long and 2–6.5 cm wide, unequal-sided, slightly decurrent on one side, with the collective vein set back from the margin. Cataphylls surrounding the peduncle, 10–27 cm long, lanceolate.
INFLORESCENCE:
Peduncle 15–35 cm long, slender. Spathe 4–6 cm long, when expanded up to 4.2 cm wide, convolute around the lower part of the inflorescence, erect, very broadly ovate, acute.
Spadix up to twice as long as the spathe. Female flower zone about 2 cm long and 1 cm thick; male flower zone 4–5 cm long, 1–1.5 cm thick, or up to 2.5 cm thick in its upper part, elongate-conical or obconical. Appendix 7–10 cm long and 1.5–4 cm thick, elongate-conical or conical, more or less obtuse.
Male flowers forming rather densely crowded circular or oval groups below, and above forming more or less interrupted transverse rings. Stamens 1 mm long and 1.5 mm wide, sessile; thecae obovoid, dehiscing by a kidney-shaped apical slit.
Pistils somewhat separated; ovaries subglobose, 3 mm long; styles approximately as long as the ovaries, crowned by cushion-shaped stigmas. Berries about 1.4 cm long, oblong, one-seeded.
PROPAGATION:
Cuttings taken in mid-August rooted at 100%, but we have not re-tested this species. With proper timing, this was among the species that rooted at the highest percentages in the trials.
ETYMOLOGY:
From the Latin interruptus, meaning “interrupted,” “broken,” or “discontinuous,” referring to the striking arrangement of the male flowers. In the upper part of the male zone, the flowers are organized into conspicuous transverse rings that are broken or interrupted rather than forming continuous bands. Engler and Gehrmann explicitly described this character in the protologue as annulos ± interruptos transversales formantes — “forming more or less interrupted transverse rings.” These raised, collar-like bands are among the most distinctive features of Amorphophallus interruptus and are especially evident in living plants.
NOTES:
1. Some Amorphophallus species, such as Amorphophallus ongsakulii or Amorphophallus interruptus have small and frail inflorescences or a very tight spathe entrance, which excludes pollinators of a larger size.
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Amorphophallus interruptus Engl. & Gehrm.
2. Pflanzenr., IV, 23C: 90 (1911) — protologue.
3. Alan Galloway — Amorphophallus interruptus, alangallowaybotanicals.com.
4. Plant Signaling & Behavior 16 (12): Odor polymorphism in deceptive Amorphophallus species
5. Das Pflanzenreich IV.23c (Araceae-Lasioideae), Fig. 37: 107 (1911)
6. Propagation of Amorphophallus by Leaf Petiole Cuttings — Juniper Level Botanic Garden