Scientific Name:
Senna Mill., Gard. Dict., ed. 4, 3, (1754)
Vernacular Name(s):

Herbs, shrubs or trees, not armed.  Lvs paripinnate or reduced to phyllodes;  petiolar glands often present;  stipules various.  Infl. axillary, racemose or paniculate;  bracts and bracteoles various.  Calyx with a very short tube and 5, often unequal, segments imbricate in bud. Corolla usually yellow, rarely white;  petals subequal.  Stamens free, 10 and all fertile, or some reduced to staminodes, or 5 and fertile;  anthers uniform or a few larger, basifixed, opening by the apex.  Style curved; stigma terminal.  Pod various, compressed or terete, 1–2-valved, or indehiscent.

[From:  Webb et al. (1988) Flora of New Zealand. Volume 4.]

Number of species in New Zealand within Senna Mill.
Exotic: Fully Naturalised2
Exotic: Casual5
Mabberley, D.J. 2008: Mabberley's plant book, a portable dictionary of plants, their classification and uses. Edition 3. Cambridge University Press.
Miller, P. 1754: The Gardeners Dictionary. Vol. 3. Edition 4. London.