T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Melianthus major (Cape honey flower)

Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Geraniales
Family: Melianthaceae
Genus: Melianthus
Species: M. major
Binomial name: Melianthus major
Common names: Honey bush, Giant honey flower, Cape honey flower, Tall Cape honey-flower, False castor oil plant

Melianthus major is a smelly species of flowering plant in the family Melianthaceae. It is an evergreen, woody, suckering shrub, endemic to South Africa and now naturalised in India, Australia and New Zealand.
Melianthus major has stout, rough, soft-wooded, hollow stems, and a suckering root system. It grows to 2–3 m tall by 1–3 m wide. It has frond-like pinnate leaves which are opposite and up to 1 m long.  The leaves divided into >21 distinctively folded leaflets that are >15 cm long. The leaflets are grey-green and are glaucous especially underneath and their margins are serrated with 1 cm sharp teeth.
During the months of July, August, September, October, November, December, January, February, March, April Melianthus major develops an erect flower stalk >80 cm tall with a terminal inflorescence that has 2 cm long, dark-reddish brown, foul-smelling flowers. The flowers are full of nectar. 
The flowers are followed by inflated, greed pods >5 cm long that ripen and dry. They contain 6 mm shining, black, keeled seeds.

This invasive plant is common in the north of New Zealand where large coastal infestations can be found on coastal sands and estuaries and inshore islands. In the North Island, it is occasionally found coastally further south especially on the east coast. In the South Island, it is found locally from Farewell Split to the Bluff but only in coastal areas.
It is spread occasionally by wind but usually by its seed capsules are carried by fresh or sea water. The suckering roots are also spread by the dumping of vegetation. Once it is established it smothers low growing coastal plants often allowing invasive vines to take hold.

Melianthus major is very poisonous and has caused death in people and animals. The entire plant is toxic, especially the roots. 
The plant contains toxic bufadienolides (cardiac glycosides). Ingestion by humans and animals can produce symptoms of increased salivation, vomiting, bloody diarrhoea, cyanosis of the mucous membranes, rapid weak pulse, and extreme exhaustion. Dead animals show haemorrhage and oedema of the lungs, pericardial haemorrhage, general cyanosis and congestion of the liver and kidney. Livestock rarely ingests the plant because of the unpleasant smell, but may be forced to during drought and scarcity of grazing.
The dark honey produced from the characteristic black nectar may be toxic. New Zealand’s nectar feeding birds like the silvereye, bellbird, and tui may be affected.

The smelly flower inflorescence.

The distinctive leaflets.

Cape Honey flower. Melianthus major. Botanical Register, vol. 1 (1815) [S. Edwards] Giant 

Thanks to Wikipedia for text and Information:  http://creativecommons.org/licenses/by-sa/3.0/