Smooth senna, arsenic bush, buttercup bush
Senna septemtrionalis, Fam. Caesalpiniaceae
Erect glabrous shrub to 4m tall. Previously Cassia floribunda.
Other invasive plants
Invasive plants that are not prohibited or restricted invasive plants, but are known to spread readily and cause negative impacts, within the region.
|Form or habit:||Shrub|
Alternate pinnate with opposite stalkless or shortly stalked leaflets, lacking a terminal leaflet; usually increasing in size from lower to upper pairs. Total length 60-80mm, including the round 15-30mm stalk. Four to five pairs of ovate leaflets, 45-70 x 15-28mm, tapering into a pointed apex; 3-4 erect club-shaped glands present between the lowermost pairs of leaflets.
|Flower description:||Yellow somewhat orchid-like or cup-shaped with 5 sub-equal-sized petals; about 10-15mm long, borne in terminal or upper axillary 5-10 flowered sprays.|
|Fruit description:||Pods brown cylindrical glabrous straight or slightly curved, 50-80 x 10-15mm, containing up to 60 oval to pear-shaped flattened shiny olive-green seeds, about 5 x 4mm.|
|Food source for:|
|Toxicity:||Toxic if ingested|
|Origin:||Mexico and South America|
|Notes:||Spread by: seeds expelled from opening pods, water, contaminated soil on machinery (harvesting, earthmoving, and 4WDs), animal hooves, manure, contaminated harvest material and fodder. Invades/threats: everywhere grazing, agriculture and the environment are all under threat. Notes: probably originated as a garden ornamental. It is a threat to primary industries as well as the environment. To date it does not appear to be wide-spread in this district but is known to occur at Eungella and Crediton. Weedy sennas produce numerous seeds that, in a short time, may accumulate a large soil seed-bank. As seeds remain viable for up to a decade or more, germination can take place over many years, whenever conditions are suitable. They are capable of forming dense stands and compete with pastures and crops for light, moisture and nutrients. Most species are toxic to cattle and while mature pods and seeds are sometimes eaten, the plants are relatively unpalatable and soon die off. Environmental weed.|
|Information sources:||Mackay Regional Pest Management Group (2018) Weeds of the Mackay Whitsunday Region Second Edition.|