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Tacca leontopetaloides (L.) Kuntze 1891
pronounced: TAK-kah lee-on-toh-pet-al-OY-deez
Dioscoreaceae – the yam family. Sometimes placed in Taccaceae
common name: Polynesian Arrowroot
Most authorities now classify plants according to the Angiosperm Phylogeny Group System (APG). When this was first published in 1998, Taccaceae was described as a separate family, containing only the Tacca genus. The 2003 revision of the system (APG II) placed all these plants in the Dioscoreaceae. Tacca is from the Malayan word for the Black Bat plant; leontopetaloides is from the Greek λεοντος (leontos), of a lion, and πεταλον (petalon), a leaf.
This extraordinary-looking plant is found in northern Australia, and southwards along the Queensland coast as far as central Queensland. It also occurs in Africa, Madagascar, Asia, Malesia and the Pacific Islands. It usually grows in open forest, but is occasionally found in monsoon forest and also in or on the margins of lowland rain forest. The plant photographed was growing around the base of a gum tree on vacant land opposite the clinic in Nelly Bay.
The true stem of the plant is a starchy underground tuber – it does not have an aerial stem. The leaves, arising directly from the tuber, are very variable, deeply divided, and generally bipinnate or tripinnate. The petioles are about 20 – 100 cm long, longitudinally ribbed, and the leaves themselves 30 – 70 cm long and up to 120 cm wide. The upper leaf surface has depressed veins, and the lower surface is shiny with bold yellow veins.
The inflorescences are borne on tall stalks, up to about 150 cm, also arising directly from the tuber – the foliage and the flowers have no connection above the ground. The flowers are in an umbel, about 20 flowers per umbel, subtended by quite a large number of trailing green to purple filiform bracts about 10 – 20 cm long. The tepals are green, sometimes with purple tips, in 2 whorls of 3. The anthers are attached to a hood-like structure. The stigma is 3-lobed, and each lobe is divided into two.
The fruits are ovoid, ribbed up to about 3 by 2 cm long, the tepals persistent at the apex. They emit a strong fruity odour when cut or broken. There are numerous seeds about 5 – 8 by 4 – 6 mm in size, their surface striated.
The plant is usually dormant for part of the year, and dies down to he ground. Later on, new leaves will arise from the tuber.
Until the introduction of cassava, the tubers were much used in the Pacific region as a source of starch. They are hard and potato-like, with a brown skin and white interior. They were grated, and then allowed to soak in fresh water. The settled starch was then rinsed repeatedly to remove the bitterness, and dried. In most places it is now little used in this way, due to the availability of other starches that involve less work to produce.
In traditional Hawaiian medicine, the raw tuber was mixed with water and red clay and eaten, to treat internal hæmorrhaging, diarrhœa and dysentery. It was also applied externally to wounds to stop bleeding. The starch was also used to stiffen fabrics.
Information about medicinal qualities of plants, or about their use as medicines, is for interest only, and is not intended to be used as a guide for the treatment of medical conditions.
Photographs taken in Nelly Bay 2015
Page last updated 7th March 2018