Lantana
Lantana (Lantana camara) is a Weed of National Significance and is prohibited from sale or trade across Australia. It is a particularly serious environmental weed throughout eastern Australia and is toxic. It has naturalised from Geraldton to the south coast, particularly along the rivers, creeklines, and in wetlands around Perth.
This vigorous, drought-tolerant plant has flowers that are plain yellow, or combinations of yellow, red, pink, orange or cream, followed by berries that birds eat and spread to bushland via their droppings.
In the garden, too, this lantana can become a problem when it forms dense, tangled thickets up to three metres high. Pulling it out is difficult for most people because, even if it is killed with herbicide, the woody stems remain and are covered with hooked prickles. It might be necessary to employ a garden maintenance contractor to remove it, using proper equipment.
Some yellow-flowered forms are often mistakenly labelled as sterile, or as the groundcover form Lantana montevidensis which is permitted but only has purple or white flowers, never yellow.
Morning glory
Two related vines that cause enormous problems for gardeners are the blue morning glory (Ipomoea indica), and mile-a-minute (l. cairica) which has pinkish mauve flowers. Both species are commonly called morning glory.
In domestic situations morning glory can invade gutters and eaves, cover most other plants, and jump the fence to wreak similar havoc in neighbouring properties. Apart from its rampant vegetative growth it also seeds prolifically. Morning glory has invaded bushland from Geraldton to Albany and is common along rivers and creeks in the Perth area, where it blankets trees and shrubs.
Removing morning glory from the garden requires persistence. A glyphosate herbicide can knock it back, but it may be necessary to repeat the applications many times before the vine dies.