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

Spartium junceum (Spanish broom)

Kingdom: Plantae
Divisions: Magnoliophyta
Class: Magnoliopsida
Order: Fabales
Family: Fabaceae
Subfamily: Faboideae
Tribe: Genisteae
Genus: Spartium
Species: S. junceum
Binominal name: Spartium junceum
Common name: Spanish broom, Weaver's broom

Spartium junceum is a vigorous medium-sized deciduous shrub native to the Mediterranean, southern Europe, southwest Asia and northwest Africa. In New Zealand, it is classed as a noxious weed because of its prolific seed production and aggressive replacement of native plants. It is common in Auckland, Hawkes Bay, Wellington, Nelson, Christchurch and the Otago Peninsula. It invades pasture, roadsides, forestry blocks, low alpine areas, native grasslands, dry scrubland and braided riverbeds. Because the broom species are nitrogen-fixing colonising plants they can alter the soil composition increasing the potential for further weed invasion

Spartium junceum can grow up to 4 m tall. It has thick, somewhat succulent, tough, grey-green, rush-like shoots with very sparse small, simple, deciduous leaves 1 to 3 cm long and up to 4 mm broad. The leaves are of little importance to the plant, with much of the photosynthesis occurring in the green shoots (a water-conserving strategy in dry climates). 
It produces masses of large bright yellow pea-like flowers > 2 cm during September to March. Flowering is followed by long brown or black seed pods (8-10 cm). When mature they burst open spreading the seeds to adjacent areas.

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