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Sida rhombifolia L. 1753
pronounced: SEE-duh rom-bih-FOE-lee-uh
(Malvaceae – the hibiscus family)
synonym: Malva rhombifolia (L.) E.H.L.Krause 1901
pronounced: MAL-vuh rom-bih-FOE-lee-uh
common names: Arrow-leaf Sida, Paddy’s Lucerne
Sida comes from the Greek word σιδη (sidé), used in classical times as a common name for both the pomegranate and the yellow water-lily Nuphar luteum; rhombifolia is from the Greek ρομβος (rhombos), a rhombus – a quadrilateral with all sides equal – and the Latin folium, a leaf. In the synonym, malva is Latin for ‘mallows’. Malva is the type genus for the Malvaceae family, and the word ‘mallow’ itself is interesting. It has come from the Latin malva via the Old English word malwe. It is not known for certain where the Latin malva originated: it is thought to be either from the ancient Greek word μαλαχη (malaché), yellow, or from the Hebrew מלוח (malúakh), salty.
This common weed is a perennial or sometimes annual plant native to the New World tropics and sub-tropics. Other common names include Jelly Leaf and, somewhat confusingly, Cuban jute, Queensland hemp and Indian hemp, although it is related neither to jute nor to hemp.
The stems are erect to sprawling and branched, growing to a height of 50–120 cm, with the lower sections being woody. Here, it is more often seen in lawns or on road verges, where it assumes a stunted form through frequent mowing. Plants develop a thick taproot, as anyone who has tried to pull them up from the lawn will have noticed. The dull green lanceolate to linear-oblong and sometimes rhombic leaves are arranged alternately along the stem, 4–8 cm long (in unmown plants), with petioles that are less than a third of the length of the leaves. The leaves are paler below, with short greyish hairs. The apical halves of the leaves have serrate margins, while the rest of the leaves are entire. The petioles have short spiny stipules at their bases.
The flowers are quite delicate, and occur singly on flower stalks that arise from the area between the stems and leaf petioles. They consist of 5 petals each 4–8 mm long, creamy to orange-yellow in colour, and may be somewhat reddish in the centre. Each of the overlapping petals is asymmetric, having a long lobe on one side. The stamens unite in a short column. The fruit is a ribbed capsule, which breaks up into 8–10 segments. In the fruit, the mericarps are hard and often indehiscent, with a wide back and honeycombed or reticulate sides. The mericarps have 2 erect minutely barbed awns. The plant blooms throughout the year.
This species is usually confined to waste ground, paddocks, gardens, disturbed forests and roadsides; it can be competitive in pasture, due to its unpalatability to livestock. It is very common throughout Australia, especially in tropical to warm temperate open grassy areas – it tolerates most soil types. It remains evergreen in the tropics, but dies back in temperate areas, to regrow from root buds.
Among the Lepidoptera larvae that feed on the plant are:
Photographs taken in Picnic Bay 2010
Page last updated 21st February 2018