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

Senna septemtrionalis (Buttercup bush)

Kingdom:   Plantae
(Unranked):        Angiosperms
(Unranked):        Eudicots
(Unranked):        Rosids
Order:       Fabales
Family:      Fabaceae
Subfamily: Caesalpinioideae
Tribe:        Cassieae
Subtribe:    Cassiinae
Genus:      Senna
Species:     S. septemtrionalis
Binomial name: Senna septemtrionalis
Synonyms: Cassia aurata, C. elegans, C. floribunda auct, C. laevigata, C. laevigata var. floribunda, C. quadrangularis, C. septemtrionalis, C. vernicosa
Common names: Buttercup bush, Smooth senna, Yellow shower, Arsenic bush,  Dooleyweed,

Senna septemtrionalis is a plant in the originating from Mexico and Central America.  It can be invasive and can invade forest margins, riverbanks, roadsides and waste ground where it can establish and suppress the regeneration of desirable species. This plant spreads by reseeding itself, and the seeds may be contaminants of soil and garden waste.

Senna septemtrionalis is a shrub or tree growing from 1-5 m tall. The stem is rough but hairless. Its once-compound leaves (6-10.5 cm long) have 3-5 pairs of leaflets with pointed tips. The leaves are pinnate, smooth, bright green and are paler beneath.  The leaves have a small cone-shaped structure between the lowest three or four pairs of leaflets.
Its yellow flowers are on axillary racemes (1.5-8) cm long. They have five petals and six or seven fully-formed stamens, two of which are larger than the others.
The fruit is green cylindrical pods (5-10 cm long and 7-12 mm wide) and are usually borne in an upright position on stiff stalks. On maturity, they turn brown.

The undersides of the leaves.

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