Native rosella biology
: Malvaceae (Hibiscus family).
: Native rosella.
: Wide leaf bladder ketmia (Hibiscus trionum var. vesicarius)
at early seedling stages.
- are similar in shape with one leaf almost circular with a slightly flattened base and the other broadly egg-shaped often with a notched base, and larger. Both leaves are hairy, 16.5 – 19 mm long and 20 – 21 mm wide, on stalks that are 14 – 17.5 mm long.
- the first true leaf is roughly egg-shaped with a notched base, wrinkled in appearance, hairy, and has shallow teeth around the margins. The second and subsequent leaves become increasingly wrinkled, toothed around the margin with more prominent veins.
– are three to five lobed, up to 140 mm long and wide, sparsely to coarsely hairy, with heart-shaped bases and borne on stems that are 10 - 200 mm long.
– are erect, woody, to 200 cm high, with hairy green or red stems.
– white hibiscus-like five-petalled flowers with deep red or purple-black centres, to 30 mm wide and on stalks that are 10 – 15 mm long. Flowers are borne in the upper leaf forks and, on older plants, on long flowering stems to 300 mm with 5 to at least 20 flowers.
– are hairy and sticky, oval-cylindrical in shape, 25 – 40 mm long and 13 – 20 mm wide, have five prominent ribs and a short beak. Initially mid to dark green these pods turn dark brown on maturity and split from the tip into five segments to release 10 – 20 dark brown to black spherical seeds, 2.5 – 4 mm in diameter, covered in hairs.
: Germination occurs in spring and summer after rainfall and irrigation. The plant has rapid growth over spring and summer with flowering, several months after emergence through summer and autumn. Mature seed is produced within a month of flowering during late-summer and autumn when the long seed head stalks are a common sight above the cotton canopy.
: The plant is found on heavy cracking black clay soils and is a common weed of cultivation from Central Queensland into northern Australia.
: The plant is a common weed of summer crops including dryland and irrigated cotton. There are no herbicides registered for the control of this weed. The weed produces a large number of seeds that are probably long-lived in the soil, making control and eradication difficult.
: A native species found throughout the northern half of Australia.
Crop Weeds of Northern Australia, p. 135 - 136.