Amorphophallus is a large genus of some 200 tropical and subtropical tuberous herbaceous plants from the arum family (Araceae), native to Asia, Africa, Australia and various oceanic islands.Sedayu, A., C. M. Eurlings, Gravendeel, B., & Hetterscheid, W. (2010). Morphological character evolution of Amorphophallus (Araceae) based on a combined phylogenetic analysis of trnL, rbcL and LEAFY second intron sequences. Botanical Studies, 51, 473–490. The genus includes the Titan arum (A. titanum) of Indonesia, which has the largest inflorescence in the genus, and is known as the 'corpse flower' for the pungent odour it produces during its flowering period, which can take up to seven years of growth before it occurs.
A few species are edible as "famine foods" after careful preparation to remove irritating chemicals.
History The oldest systematic record of the plants was in 1692, when Van Rheede tot Drakenstein published descriptions of two plants. The name "Amorphophallus" was first mentioned in 1834 by the Dutch botanist Blume from Ancient Greek "without form, misshapen" and "penis", referring to the shape of the prominent spadix. Between 1876 and 1911, Adolf Engler merged a number of other genera into Amorphophallus, with a final monograph published in 1911.
Distribution These are typical lowland plants, growing in the tropical and subtropical zones of the paleotropics, from West Africa through the Pacific Islands. None of them are found in the Americas, although a remarkably similar but not closely related genus, Dracontium, has evolved there. Most species are endemic. They grow preferentially on disturbed grounds, such as secondary forests.
Description
These small to massive plants grow from a subterranean tuber. Amorphophallus tubers vary greatly from species to species, from the quite uniformly globose tuber of A. konjac to the elongated tubers of A. longituberosus and A. macrorhizus to the bizarre clustered rootstock of A. coaetaneus. The weight of these tubers range from as little as in Amorphophallus pusillus of Vietnam to as much as for Amorphophallus titanum. From the top of this tuber a single leaf, which can be several metres across in larger species, is produced atop a trunk-like petiole followed, on maturity, by a single inflorescence. This leaf consists of a vertical leaf stalk and a horizontal blade, which may consist of a number of small leaflets. The leaf lasts one growing season. The peduncle (the primary flower stalk) can be long or short.
As is typical of the Arum family, these species develop an inflorescence consisting of an elongate or ovate spathe (a sheathing bract) which usually envelops the spadix (a flower spike with a fleshy axis). The spathe can have different colours, but mostly brownish-purple or whitish-green. On the inside, they contain ridges or warts, functioning as insect traps.
The plants are monoecious. The spadix has tiny flowers: female flowers, no more than a pistil, at the bottom, then male flowers, each with one stamen, and then a blank sterile area. This last part, called 'the appendix', consists of sterile flowers, called staminodes, and can be especially large. The flowers do not have corollas.
Mature female flowers are usually receptive for only one day. In many species, the inflorescence emits a scent of decaying flesh in order to attract insects, though a number of species give off a pleasant odour. Through a number of ingenious insect traps, pollinating insects that entered a spathe when female flowers were receptive remain inside the spathe for about one day while male flowers mature and release pollen. Pollen falls on these insects, and they carry pollen as they exit the spathe and can pollinate female flowers in another spathe. Amorphophallus species are used as food plants by the larvae of some Lepidoptera (butterfly and moth) species including Palpifer sexnotatus and Palpifer sordida.
Pollinated flowers usually each develop into a globose berry, a fruit. The berries are red, orange-red, white, white and yellow, or blue, depending on the species.
Notable species The species Amorphophallus titanum, 'corpse flower' or titan arum, has the world's largest unbranched inflorescence, with a height of up to and a width of . After an over -tall flower opened at Chicago Botanic Gardens on 29 September 2015, thousands lined up to see and smell it. The floriculturalist described it as smelling "like roadkill, a barnyard, a dirty diaper, very strong, a little bit of mothball smell too". Native to the Indonesian rainforest, it takes about 10 years to blossom. Dubbed "Alice", its bloom was broadcast via live webcam. It is one of two plants at the Chicago Botanic Gardens, which kept open until 2 am on September 30 to accommodate visitors.
A runner-up is Amorphophallus gigas, which is taller but has a somewhat smaller inflorescence.
Amorphophallus konjac tubers are used to make , a Japanese thickening agent and edible jelly containing glucomannan.
Some species are called voodoo-lily, as are some species of Typhonium (also in the Araceae).
Taxonomy and systematics
The genus was divided into 4 subgenera based on phylogenetic analysis in 2017, with a number of SE Asian genera currently unplaced:
Subgenus Amorphophallus Image Name Year Distribution Amorphophallus adamsensis 2013 Philippines Amorphophallus angulatus 1994 Borneo (Sarawak) Amorphophallus ardii 2020 Sulawesi Amorphophallus asper 1911 Sumatera Amorphophallus bangkokensis 1941 Thailand Amorphophallus beccarii 1880 Sumatera Amorphophallus borneensis 1911 Borneo Amorphophallus boyceanus 2001 Thailand and Peninsular Malaysia Amorphophallus brachyphyllus 2001 Borneo (Kuching) Amorphophallus bufo 1909 Malaysia Amorphophallus calcicolus 2021 Philippines Amorphophallus caudatus 2020 Philippines Amorphophallus cidarioides 2020 Philippines Amorphophallus commutatus 1879 Western India Amorphophallus costatus 1994 Borneo (Sarawak, Kalimantan) Amorphophallus declinatus 1994 Philippines Amorphophallus decus-silvae : West-Java giant amorphophallus 1863 Java Amorphophallus discophorus1920 Java Amorphophallus eburneus 1989 Borneo (Sarawak) Amorphophallus elegans 1922 Peninsular Malaysia Amorphophallus flammeus 2022 Philippines Amorphophallus fontarumii 2022 Philippines (Luzon) Amorphophallus forbesii 1911 Sumatra Amorphophallus fornicatus 2020 Philippines (Luzon) Amorphophallus galbra1893 New Guinea to N. Australia Amorphophallus gigas : Sumatra giant amorphophallus1862 Sumatra Amorphophallus hewittii 1920 Borneo Amorphophallus hirsutus 1862 Nicobar Islands, W. Sumatra Amorphophallus hottae 1992 Borneo (Sabah, Sarawak) Amorphophallus infundibuliformis 1994 Borneo Amorphophallus julaihii 2004 Borneo (Sarawak) Amorphophallus juliae 2010 Borneo (Sarawak) Amorphophallus koratensis Gagnep. 1941 Cambodia, Laos, Thailand Amorphophallus lambii Mayo & Widjaja1982 Borneo Amorphophallus linguiformis Hett.1994 Borneo (Kalimantan) Amorphophallus longispathaceus Engl. & Gehrm.1911 Philippines (Mindanao) Amorphophallus longistylus Kurz ex Hook.f.1893 Andaman Islands. Amorphophallus luzoniensis 1915 Philippines (Luzon) Amorphophallus malkmus-husseinii 2019 Laos Amorphophallus manta 1994 Sumatra to Peninsula Malaysia Amorphophallus merrillii1912 Philippines Amorphophallus minimus 2021 Philippines Amorphophallus minor 1904 Peninsula Malaysia Amorphophallus myosuroides 2006 Laos Amorphophallus niahensis 2010 Borneo (Sarawak) Amorphophallus obovoideus 1922 Sumatra Amorphophallus obscurus 2001 Thailand Amorphophallus ongsakulii 2006 Laos Amorphophallus opertus 1994 Vietnam Amorphophallus paeoniifolius : Whitespot giant arum, elephant yam1977 Andaman Island, Assam, Bangladesh, Borneo, Cambodia, China South-Central, China Southeast, East Himalaya, Hainan, India, Java, Laos, Lesser Sundas Is., Malaya, Maluku, Myanmar, New Guinea, Northern Territory, Philippines, Sri Lanka, Sulawesi, Sumatra, Taiwan, Thailand, Vietnam Amorphophallus palawanensis 1992 Philippines Amorphophallus pendulus : Brunei amorphophallus 1986 Borneo (Brunei, Sarawak) Amorphophallus plicatus 1936 Sulawesi Amorphophallus polyanthus 2001 Thailand Amorphophallus prainii 1893 Laos, Malaya, Sumatera, Thailand Amorphophallus pulchellus 2013 Laos Amorphophallus pusillus 1994 Vietnam Amorphophallus ranchanensis 2007 Borneo (Sarawak) Amorphophallus rayongii 2020 Philippines Amorphophallus rostratus 1994 Vietnam Amorphophallus rugosus 1994 Borneo (Sabah) Amorphophallus sagittarius 1953 Java Amorphophallus salmoneus 1994 Philippines Amorphophallus scaber 1994 Philippines Amorphophallus serrulatus 2006 Thailand Amorphophallus spectabilis 1879 Java Amorphophallus sumawongii 1985 Thailand Amorphophallus terrestris 2012 Thailand Amorphophallus tinekeae 2001 Borneo Amorphophallus titanum : Titan arum, krubi (largest flower structure on earth) 1879 Sumatra Amorphophallus urceolatus 2020 Philippines Amorphophallus variabilis 1873 Jawa to Lesser Sunda Islands, Philippines Amorphophallus venustus 2001 Borneo Amorphophallus verticillatus 1994 Vietnam Amorphophallus yaoi 2020 Philippines Amorphophallus samarensis 2024 Philippines
Subgenus Scutrandrium Image Name Year Distribution Amorphophallus albispathus 1994 Thailand Amorphophallus albus 1984 China (Sichuan, Yunnan). Amorphophallus annulifer 1994 Java Amorphophallus asterostigmatus 1992 Thailand Amorphophallus bantae 2024 Thailand (Sa Kaeo) Amorphophallus bognerianus 2009 India (Arunachal Pradesh) Amorphophallus carneus 1904 Malayasia, Thailand Amorphophallus chlorospathus 1893 India, Myanmar Amorphophallus coudercii 1985 Cambodia, Laos, Thailand and Vietnam Amorphophallus curvistylis 1994 Thailand Amorphophallus echinatus 1985 Thailand Amorphophallus excentricus 1994 Thailand, Malaysia (Pulau Langkawi) Amorphophallus fallax 2012 Vietnam Amorphophallus flotoi 2018 Cambodia, Laos, Thailand, Vietnam Amorphophallus fuscus 2006 Thailand Amorphophallus glaucophyllus 2006 Thailand Amorphophallus haematospadix 1893 Thailand, Malaysia (Pulau Langkawi) Amorphophallus hohenackeri 1911 India Amorphophallus kachinensis 1911 China (Yunnan, Guangxi), Laos, Myanmar, Thailand Amorphophallus konjac : Devil's tongue, elephant foot, elephant-yam, leopard palm, snake palm, umbrella arum, voodoo lily 1858 China (Yunnan) Amorphophallus khammouanensis 2015 Laos Amorphophallus krausei 1911 China (Yunnan), Laos, Myanmar, Thailand Amorphophallus kuznetsovii 2012 Vietnam Amorphophallus lacourii 1878 Cambodia, Laos, Thailand, Vietnam Amorphophallus lanceolatus 2012 Vietnam Amorphophallus longituberosus 1911 Bangladesh, Malaya, Thailand Amorphophallus macrophyllus 2012 Thailand, Vietnam Amorphophallus maxwellii 1994 Thailand Amorphophallus nicolsonianus 1986 India (Kerala) Amorphophallus napalensis 1985 Bangladesh, Bhutan, Nepal, Myanmar, and India Amorphophallus purpurascens 1893 Myanmar Amorphophallus ravenii 2018 Laos Amorphophallus rhizomatosus 1994 Laos, Vietnam Amorphophallus saraburensis 1941Thailand Amorphophallus schmidtiae 2006 Laos Amorphophallus scutatus 2001 Thailand Amorphophallus smithsonianus 1989 India Amorphophallus tenuistylis 1994 Cambodia, Thailand Amorphophallus tenuispadix 1994 Thailand Amorphophallus wasa 2022 Myanmar
Subgenus Metandrium