AMORPHOPHALLUS JOHNSONII
PROTOLOGUE:Amorphophallus johnsonii N.E.Br., published in Flora of Tropical Africa 8: 156 (1901). The protologue is reproduced below.
SYNONYMS:
HETEROTYPIC SYNONYMS: Amorphophallus accrensis N.E.Br. in D.Oliver & auct. suc. (eds.), Fl. Trop. Afr. 8: 157 (1901) Amorphophallus purpureus (Engl.) Engl. & Gehrm. in H.G.A.Engler (ed.), Pflanzenr., IV, 23C: 83 (1911) Hydrosme purpurea Engl. in Mém. Soc. Bot. France 9: 25 (1907)
DISTRIBUTION: W. Trop. Africa: Benin, Burkina Faso, Ghana, Guinea, Ivory Coast, Liberia, Mali.
DISTRIBUTION NOTE: Historical: Kwabu, Gold Coast (type collection, Johnson 643) Modern: Ghana: Kwahu, Eastern Region.
SPECIES DESCRIPTION:
Tuber globose when young, later depressed globose, rarely producing short, cylindric offsets. Leaf solitary; petiole to 100 cm long, bright green with dark green spots; lamina to 100 cm in diam.; leaflets broadly oval, to 12 cm long, acuminate.
INFLORESCENCE:
Inflorescence developing just before the leaf, short- or long-peduncled; peduncle 10-95 cm long, as petiole; spathe erect, to 21 cm long, base and limb separated by a distinct constriction, base elongate, outside greenish, inside yellowish green or dark green, covered with fleshy, purple hairs, limb outside green or reddish brown, towards the margin purple, inside purplish. Spadix longer than spathe, to ca. 50 cm long.
ECOLOGY:
Found in Ghanaian rain forest; flowers soon after the first heavy rains, in late March and April, during the main rainy season
ETYMOLOGY:
Named for Johnson, the collector of the type specimen, cited in the protologue only as “Kwabu, Johnson, 643” from the Gold Coast (now Ghana) — almost certainly William Henry Johnson, a British botanist who served as Curator of the Botanic Gardens at Aburi and later directed agriculture in the Gold Coast. The Latinized epithet johnsonii means “of Johnson.” Neither the original description nor the 1996 monograph gives an explicit dedication.
NOTES:
1. A remarkable species because the inflorescences may be long- or short-peduncled, a rare polymorphism in Amorphophallus. The long-peduncled forms are found in Savannah conditions, those with short peduncles deeper in the forests. The variation in peduncle length is matched in Asia only by Amorphophallus bulbifer. Amorphophallus johnsonii differs from Amorphophallus angolensis in having sessile stigmas and more fleshy hairs.
STORY:
STORY TITLE: One night in the Jachie Sacred Grove
In April 1991, Daniel Beath of the University of Aberdeen watched fifteen Amorphophallus johnsonii come into bloom in the Jachie Sacred Grove in Ghana, and stayed through the night to see who answered the flowers' invitation. Anthesis begins at dusk: around 17:30 the exposed tip of the spadix — the osmophore — starts to smell of fish, and by 18:00 it is oozing a clear fluid and broadcasting a stench of rotting fish and faeces that carries several metres into the forest.
Between 18:30 and 18:50, carrion beetles (Phaeochrous amplus) arrive in force, flying in decreasing circles before landing on the spadix and promptly losing their grip — the inside of the spathe is slippery and concave, and the beetles tumble to its base, where the female flowers wait. Twenty-five years later, Claudel's review of pollination across the genus pointed out a second wall to the prison: the base of the appendix is broadened into an overhang above the chamber's constriction, an effective obstacle for any insect trying to climb back out. Up to 152 beetles were counted in a single bloom, crawling, copulating and stridulating loudly, some already dusted with pollen from other inflorescences. They stay trapped overnight and lie quiescent through the day — they are nocturnal, so the open inflorescence never really holds them; they simply do not leave. The plant releases them on its own schedule: between 16:30 and 16:45 the next afternoon the anthers push out long sticky threads of pollen, and after 18:00 the beetles crawl up the spadix, past the dehisced anthers, and fly off from the tip, carrying copious pollen with them.
Beath colour-coded each inflorescence and marked its trapped beetles with nail varnish to match, then watched where they turned up next. Marked beetles were recaptured in blooms 8 to 37 metres away, and their numbers fell off exponentially with distance — the regression predicts zero pollen transfer at 49 metres. Fruit set only when beetles arrived from a male-phase bloom within about 30 metres on the same evening; pollen a day old, or from farther away, failed every time. Six of the fifteen plants set fruit.
The berries ripened 67 to 74 days after anthesis, turning vivid orange from the top of the infructescence downward while the spadix elongated beneath them, spacing out the ripening fruit. For a plant on this schedule, a dense colony is not a luxury but a requirement — the pollen is only as good as the nearest neighbour flowering the same night.
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Amorphophallus johnsonii N.E.Br.
2. Flora of Tropical Africa 8: 156 (1901) — protologue.
3. Alan Galloway — Amorphophallus johnsonii, alangallowaybotanicals.com.
4. Aroideana 19 (1996):P7 - 131
6. African Plants Portal - Amorphophallus johnsonii
7. The many elusive pollinators in the genus Amorphophallus. Arthropod-Plant Interactions 15 (73)