Century plant
Botanical Name
Agave americana
Family
Agavaceae (yucca, agave, flax, cabbage tree)
Where is it originally from?
Mexico
What does it look like?
Stout, succulent, rhizomatous perennial, with leaves in a basal rosette. Rigid, leathery, hairless, fleshy leaves (1-2 m x 15 cm) are triangular in cross section, with margins lined with raised, coarse 5 mm teeth 4 cm apart, and tipped with a conical, hard spine (25 mm long). Flowering stems, which are 7-10 m tall and produced rapidly at maturity (after 10-15 years), are candelabra-like clusters of many yellow flowers borne on branches off the main stem which are followed by seed capsules containing black seeds (5 cm long). After flowering the basal rosette dies and is replaced by several small lateral rosettes (daughters).
Are there any similar species?
Yucca species and Furcrea foetida are similar.
Why is it weedy?
Tolerates extreme drought, wind, salt, high temperatures, poor soil and low fertility, recovers from damage and is not grazed by stock, is long-lived and has no known parasites. It is taller than other plants in the habitat. New daughter plants are formed via short rhizomes, and succulent leaves resprout from fragments.
How does it spread?
Daughter plants, seed and stem fragments are carried to new sites by ocean tides, by deliberate plantings, soil movement especially down banks, dumped vegetation, and naturally as garden escapes.
What damage does it do?
Replaces vulnerable dune species, colonises bare sand, causes build-ups of sand which can lead to new (usually exotic) habitats being formed and erosion elsewhere, and also causes pedestrian traffic pressure on nearby species as people try to avoid the Agave plants.
Which habitats is it likely to invade?
Moving and consolidated sand, cliffs, estuarine and other coastal areas, cliffs, bluffs, rocky areas, and inshore islands.
What can I do to get rid of it?
1. Physical removal - Dig or pull out scattered plants. Dispose of plant material at a landfill or refuse transfer station
2. Stem inject - 4-10 jabs (depending on size of plant) of 5ml glyphosate (undiluted). Leave to rot on site.
3. Cut and stump treat- Slash 4-10 lengthwise cuts (depending on size of plant) and apply glyphosate gel (120g/L) to each cut. Leave to rot on site.
When a gel is inadequate a solution of diesel and triclopyr (20:1 diesel:triclopyr) or commercial formulations (120g triclopyr/l of oil, or triclopyr /picloram mixes (TP)) can be used. Here it is important that the herbicide solution is painted over the entire exposed surface of the cut stump, i.e. top and sides.
Dispose of leaves at a refuse transfer station.
4. Leaf paint - Brush neat glyphosate (360 g/l) or glyphosate gel on underside of individual leaves on each branch. Ensure herbicide resistant gloves are worn.
CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and directions for the purchase, use and storage of the product, are followed and adhered to.
What can I do to stop it coming back?
Dropped leaf fragments resprout and daughter plants are occasionally missed. Exclude livestock permanently from sites. Always kill plants before they seed, ie before flowers appear on tall flowering stem. Follow up on sites at least annually.
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