Kingdom:   Plantae
(Unranked):        Angiosperms
(Unranked):        Eudicots
(Unranked):        Asterids
Order:   Asterales
Family:        Asteraceae
Tribe:        Senecioneae
Genus:    Ligularia
Species: L. japonicum
Cultivar name: Ligularia japonicum 'Giganteum'
Synonyms: Ligularia reniformis Ligularia tussilaginea, Farfugium japonicum var. giganteum, Farfugiun reniforme
Common name: Tractor seat ligularia (NZ only) 

  All parts of it are poisonous if ingested.

Ligularia japonicum 'Giganteum' is an evergreen foliage plant which has large, rounded, glossy, leathery leaves and daisy-like yellow flowers that originates from subtropical East Asia. It grows to a 1+m by 1m clump. Reproduction is by division or seed.
The common name is only used in New Zealand and it is named that because it looks like and is the same size as the metal seats on vintage tractors.

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Mature flowers.
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The seed heads.
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Thanks to Wikipedia for text and information:https://creativecommons.org/licenses/by-sa/3.0/