One-leaf Cape tulip (Moraea flaccida)

High Risk Weed for Kangaroo Island

One-leaf Cape tulip is an Alert weed for Kangaroo Island. Notify the Kangaroo Island Landscape Board. Early detection and control are the best way to prevent the next widespread weed.

It is a declared plant for South Australia.

THE SITUATION AND WHAT TO DO

One-leaf Cape tulip originated from South Africa and has been present in Australia since the 1880s and was used as a garden plant. It is now a significant agricultural and environmental weed.

One-leaf Cape tulip is a declared pest plant in South Australia under the Landscape South Australia Act 2019

Cape tulip is a common and widespread pest plant on Kangaroo Island. It spreads mainly through water movement, machinery, and the transport of contaminated fodder and soil. The plant primarily impacts agricultural land and neighbouring native vegetation.

The Kangaroo Island Landscape Board has run a long-term control program focused on reducing the spread of Cape tulip along roadsides and managing isolated or outlier infestations. The program has also supported landholders by promoting and providing access to equipment such as loaning weed wipers and spray units to assist with on-farm control.

To prevent spread and reduce the impacts of Cape Tulip:

landholders should control cape tulip on their property before it flowers.
practice good hygiene when moving machinery.
do not sell hay or fodder from pasture where Cape Tulip is present, and
requesting a vendor declaration when purchasing farm produce or stock feed.

If you suspect plants to be two-leaf Cape tulip, please report to the Kangaroo Island Landscape board.

DESCRIPTION

Growth form: Perennial, bulbous herb growing from an underground corm. Plants typically reach 30–60 cm tall and emerge in autumn or winter, flowering in spring before dying back over summer.
Leaves: Usually a single long, narrow, strap-like leaf arising from the base of the plant. The leaf is soft, drooping or slightly twisted, and may be 30–80 cm long but only a few millimetres wide.
Flowers: Bright salmon-pink to orange flowers with a darker central marking. Flowers are borne on slender stems and open in spring, often for only a short time on sunny days.
Fruit: A small, three-celled capsule that develops after flowering and splits open when mature.
Seed: Each capsule contains numerous small, brown seeds (up to 1,200 seeds per plant and can remain dormant for 2 to 3 years) that can be spread by water, soil movement, or contaminated fodder. However, the plant also spreads through the production of new corms and cormlets underground which can remain dormant up to 5 years.

Similar species is Two-leaved Cape tulip which has not yet been found on Kangaroo Island.

Up to 60% of corms can remain dormant through a growing season.

The leaves die back completely over summer, making the plant almost invisible during the dry period (property buyers beware!).

Impacts

One-leaf Cape tulip is highly toxic to livestock, particularly sheep and cattle, and can cause serious poisoning or death if grazed. It reduces pasture quality and productivity as stock avoid infested areas. The plant can also invade native grasslands and disturbed bushland, where it competes with and displaces native vegetation. Dense infestations can lead to economic losses for landholders through livestock deaths, reduced grazing capacity, and ongoing control costs.

CONTROL OPTIONS

Control of one-leaf Cape tulip is difficult because the plant spreads by both seed and underground corms, which can remain dormant in the soil. As a result, control usually needs to be repeated over several seasons.

Plants should be treated before flowering to prevent the development of new corms. Large infestations are commonly treated with herbicide using a weed wiper or boom spray, while individual plants can be spot sprayed, hand-wiped, or carefully dug out when the soil is moist, taking care to remove the corms.

Slashing may help reduce seed production where other control methods are not possible, but dry plants with mature seed heads should not be slashed as this can spread seed. Cultivation or fire can sometimes be used to stimulate germination, allowing follow-up control, but the risk of soil erosion should be considered before using these methods.

Permitted and on-label herbicides and rates can be found on the PIRSA Weed Control Website