Form: shrub — perennial
Status: present in WA
Probably originating in America, sida is found on most soil types except some of those derived from limestone and seasonally flooded clays. It can be found throughout the warm regions of the world. Sida is a weed of tropical pastures, when native pastures are improved by superphosphate and seeding with pasture legumes such as Townsville Stylo. Sida rapidly infests overgrazed areas near troughs and underneath shade trees. As soil nitrogen builds up under legume pasture sida spreads over the paddock competing with more palatable pasture species. In WA, sida has been found in rangelands in the East and West Kimberley.
Sida is a sparsely branched small shrub up to 1.5 metres tall with fibrous stems.
Leaves: It has light green, slightly concave oval leaves with a shiny surface and toothed margins.
Flowers: The flowers are yellow, conspicuous and borne on short stalks in leaf axils along the branches. It flowers towards the end of the wet season (February to April).
Fruit: The fruit is a dark brown capsule, it splits into six to ten single-seeded segments when ripe.
Seeds: Each seed is wedge-shaped, brown to black, with two stiff spikes at the tip.
Leaves: Leaves are bipinnate, that is they are divided twice and give a feathery appearance.
Flowers: Flowers are grouped into dense globular or cylindrical spikes, either in the axils of the leaves or at the end of branches.
Agricultural and economic impact
Environmental and pasture weed.
Declared pest category
The Western Australian Organism List (WAOL) contains information on the area(s) in which these pests are declared and the control and keeping categories to which they have been assigned in Western Australia (WA). Use the external links on this page to reach sida (S. acuta and S. cordifolia) in WAOL.
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When using any agricultural chemicals please ensure that you always follow instructions on the label and any permit. Users of agricultural chemical products must always strictly comply with the directions on the label and the conditions of any permit.
Only registered products can be used for weed and pest control.
Control methods for this plant can be found through the APVMA website, use "sida" as the pest name.