Furcraea
Mauritius hemp, Wild Sisal
Agavaceae - Furcraea spp. (F. foetida & f. selloa)
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What does it look like?

Fleshy or leathery leaves held in a rosette, with or without a basal trunk.  The leaf margins may or may not have conspicuous spines or minute teeth.  Grows up to 3m tall.  Flowers are bisexual and occur on flower spikes up to 12m tall.  Bulbils (small bulb-like structures which may fall to form a new plant) often replace flowers in the axils of leaves.  Some species produce seed (flat, black), others only reproduce via bulbils.

Preferred habitat includes open or semi-open coastal areas, including banks, cliffs and rocky outcrops, and other disturbed or open sites such as pasture, wastelands, railways and roadsides.  Tolerates semi-shade, therefore can invade open coastal pohutukawa forest, and other forests via canopy gaps, landslide scars and river banks.  May have higher survival in semi-shade than full sun in very hot regions.  Wide soil type tolerance including clay, sandy and rocky soils. Very tolerant of saline coastal conditions.

Off shore islands including Kawau and Aotea, Omaha, Leigh Habour, Scandrett Regional Park, Pakiri, Parnell, Massey. Being controlled to zero density at Mahurangi East.  Need Northland distribution data. Known to be in the dunes in Bream Bay. Widespread but scattered throughout Northland.

Why is it a problem?

History of invasiveness overseas.  Capable of forming localised mono-cultures which exclude most other plant species. Reproduces by vegetative spread.  Bulbil production can be in the order of thousands per plant under favourable conditions, leading to the formation of dense, monospecific stands around the parent plant.  The original plants themselves may also spread from the base.  In addition to predictable spread radiating from parent plant, some jump dispersal occurs via sea water dispersal and human-assisted movement.

Control Methods

Physical control

  • Many herbicides have not been effective on this species, with weed control operations on Raoul Island rcommending hand removal of plants (Champness, 1976). Plants should be pulled or grubbed out then covered with black polythene or opaque material which will prohibit light from reaching the soil (Sykes, 1984). This management should be successful if employed over the entire area of infestation due to the species being limited to only having a localised spread and lack of seed bank.

 

More Information

Control on Raoul Island of Furcraea spp.: For more information: http://www.doc.govt.nz/Documents/science-and-technical/srs98entire.pdf.

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