Family: Liliaceae

Status:

Description:
An erect perennial herb with flowering stems to about 1.2m high, which forms large clumps over time. Leaves are long and strap-like, glossy and dark green. Flowers are blue or white, tubular and held in large spherical clusters at the top of robust smooth stems about 1m long. The black, winged seeds are enclosed in a leathery green capsules which dries to pale brown. Dwarf forms are sold, which are identical to the typical form, but smaller.

Preferred habitat and impacts:
Sunny situations are preferred, but agapanthus will invade forest edges and open forest. It can also invade pasture, spreading from nearby gardens.
It forms dense stands which smother all native groundcover vegetation, prevent regeneration of trees and shrubs and eliminate habitat for native fauna. It could have an impact on fire frequency in native vegetation since the lush clumps are likely to be very fire retardant, making infested bush difficult to burn.
The leaves and roots are poisonous and can cause ulceration of the mouth.

Dispersal:
Clumps spread gradually from underground rhizomes. Dumping of garden waste can also spread the plant vegetatively. Seed is spread by wind, water and in contaminated soil or dumped garden waste. As the seed is quite large, most wind spread occurs within a short distance from the parent plant, but occasionally plants will occur several hundred metres from the parent clump.

Look-alikes:
No closely similar plants. Nerine lilies, another garden plant, are similar in form, but much less robust.
The native tussock plant spiny mat-rush (Lomandra longifolia ) could possibly be mistaken for agapanthus if neither plant was in flower, or carrying the remains of flowers. It has similar bright green strap-like leaves, but they are less fleshy than those of agapanthus, and each leaf typically has a squared tip with 1-3 small teeth.

Control:
Small infestations can be dug out, but all of the rhizome must be removed and destroyed off-site, as any rhizome left in the ground will regrow. Plants left lying on the soil surface make take root again, even if turned upside down. However, the root system is relatively shallow, so plants can be peeled over to one side and up-ended with less effort than might be expected. Agapanthus is quite resistant to herbicides. Surfactants may help improve penetration into the waxy-coated leaves.
Removal of spent flowers to prevent seed formation is sometimes proposed as a means of confining agapanthus to gardens. However, it is better to remove these plants from gardens, as seed can mature from heads which have been cut slightly too late, or on heads overlooked through being concealed by other plants. As each individual plant grows removal becomes a larger and larger job, so early removal will be much easier.