AMORPHOPHALLUS ZENKERI
PROTOLOGUE: Amorphophallus zenkeri (Engl.) N.E.Br., published in Flora of Tropical Africa 8: 159 (1901).
28. A. Zenkeri, N.E.Br. Leaf solitary; petiole 20-24 in. long, its three primary branches divided into two pinnatipartite divisions bearing 4 (often opposite) segments; terminal segments 5-5½ in. long, 2⅓-2¾ in. broad, the others smaller, all oblong-lanceolate, long acuminate, very acute, decurrent at the base. Peduncle ¾-1¼ in. long. Spathe about 8 in. long, and 4 in. diam., convolute, broadly campanulate, undulated at the purple margin; lower part of the tube clothed inside with filiform processes, blackish-purple. Spadix about twice as long as the spathe; female part about 7 lin. long, ½ in. thick, cylindric; male part ¾ in. long, ⅔ in. thick; appendix about 14 in. long, ⅔ in. thick, irregularly sulcate. Ovary shortly ovoid; stigma sessile, orbicular. - Hydrosme Zenkeri, Engl. Jahrb. xxvi. 421. Upper Guinea. Cameroons: near Yaunde, in forest, 2600 ft., Zenker & Staudt, 53.
SYNONYMS:
HOMOTYPIC SYNONYMS: Hydrosme zenkeri Engl. in Bot. Jahrb. Syst. 26: 421 (1899)
ACCEPTED INFRASPECIFICS: Amorphophallus zenkeri subsp. mannii (N.E.Br.) Ittenb. ex Govaerts Amorphophallus zenkeri subsp. zenkeri
DISTRIBUTION: Nigeria to Cameroon, Bioko: Cameroon, Gulf of Guinea Islands, Nigeria.
DISTRIBUTION NOTE: Cameroon: near Yaoundé, where Zenker and Staudt gathered it in forest.².
SPECIES DESCRIPTION:
Leaf solitary; petiole 20-24 inches [about 50-60 cm] long, its three primary branches each divided into two pinnatipartite divisions bearing four, often opposite, segments; terminal segments 5-5½ inches [about 13-14 cm] long and 2⅓-2¾ inches [about 6-7 cm] broad, the others smaller, all oblong-lanceolate, long acuminate, very acute and decurrent at the base.²
INFLORESCENCE:
Peduncle ¾-1¼ inches [about 2-3 cm] long. Spathe about 8 inches [about 20 cm] long and 4 inches [about 10 cm] across, convolute, broadly bell-shaped, wavy at the purple margin; the lower part of the tube clothed inside with thread-like processes, blackish-purple. Spadix about twice as long as the spathe; female part about 7 lines [about 1.5 cm] long and ½ inch [about 1.3 cm] thick, cylindric; male part ¾ inch [about 2 cm] long and ⅔ inch [about 1.7 cm] thick; appendix about 14 inches [about 36 cm] long and ⅔ inch [about 1.7 cm] thick, irregularly furrowed. Ovary shortly ovoid; stigma sessile, orbicular.²
ECOLOGY:
Found in forest at about 2600 feet [about 790 m].²
ETYMOLOGY:
Named in honor of Georg August Zenker (1855–1922), a German gardener, botanist, and natural-history collector whose long residence and extensive collecting in Cameroon produced important material for European museums and herbaria. The Latinized epithet zenkeri means “of Zenker.” The species occurs in Cameroon and neighboring parts of West-Central Africa.
NOTES:
1. The species is dominated by its appendix: about 14 inches of it, some 36 cm, above a spathe of about 20 cm - so the spadix runs to roughly twice the spathe.²
2. ⚠ The author had not seen a specimen. He says so on the page, and judged the plant allied to Amorphophallus mannii on the strength of Engler's description of Hydrosme zenkeri alone.²
3. The lower part of the spathe tube is lined inside with thread-like processes, blackish-purple - the same character that separates Amorphophallus staudtii in the same flora.²
4. The leaf is divided in a regular way: three primary branches, each forked into two pinnatipartite divisions, each of those carrying four segments that are often set opposite one another.²
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Amorphophallus zenkeri (Engl.) N.E.Br.
2. Flora of Tropical Africa 8: 159 (1901) — protologue.