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

Kerria japonica (Japanese rose)

Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Rosales
Family: Rosaceae
Subfamily: Amygdaloideae
Tribe: Kerrieae
Genus: Kerria
Species: K. japonica
Binomial name: Kerria japonica
Common name: Japanese rose, Kerria, Easter rose

Kerria japonica the sole species in the genus Kerria. It is a deciduous, perennial shrub in the rose family Rosaceae. It is native to China, Japan and Korea.
Kerria japonica grows to 1–2 m tall, with weak arching stems that emerging directly from the ground. The plant has rapid growth rate from its basal shoots, but slow growth rate from the established stems. It will form thickets scrambling over other vegetation or rocks.
The leaves (>5 cm long) are deciduous, alternate, ovate to lanceolate, doubly serrated, with impressed veins and an acuminate apex. 
The flowers are simple, bright yellow, with five petals and each lasts for two to three weeks. 
The fruit is a dry single-seeded achene 4–4.5 mm long.
It was first recorded in New Zealand in 1991 and is now sparingly naturalised mainly in the Waikato. It spreads mostly by basal suckers, layering and occasionally by seed.

A young leaf.

A  mature leaf.

Kerria japonica 'Pleniflora' is a double-flowered cultivar. It also a very vigorous grower and bears large, fluffy yellow flowers in spring.

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