Zingiberaceae (ginger) family
Also known as
kahili ginger, ginger lily
Where is it originally from?
What does it look like?
Non-woody perennial to 2 m tall, ginger-scented. Massive, taro-like rhizomes are long, shallow rooted, much-branched, growing over each other close to the ground surface, and form deep beds. Each rhizome segment (4 x 10 cm) usually produces an aerial stem annually. Soft, erect stems (to 2 m) are unbranched and thicken to a short pinkish 'collar' at the base. Shiny, slightly hanging leaves (20-45 x 10-15 cm) are alternate. Flowerheads (25-45 cm tall) with many fragrant, lemon-yellow flowers with conspicuous red stamens are produced from January to March and develop into a fruiting spikes with fleshy orange fruits (15-20 mm long) containing many bright scarlet seeds.
Are there any similar species?
H. flavescens, Canna species, and Zingiber spectabile are similar. Alternatives: A couple of nice natives you could try instead are Parataniwha (Elatosterma rugosum) or Rengarenga lily (Arthopodium cirratum).
Why is it weedy?
Extremely shade-tolerant, tolerates most soil types, good or poor drainage and fertility, and is drought and frost tolerant once established. Long-lived, fast growing and forms deep rhizome beds. Moderate amount of seed produced that are dispersed widely, and rhizomes resprout from any fragment and can survive immersion in the sea, crushing, and years away from soil. Wild ginger can grow within native bush. Nothing can grow up through the mats of tubers, and the dense leaves block light and smother natives.
How does it spread?
Seeds are spread by birds and possibly possums. Rhizomes spread slowly outward from clumps, and new plants are established from rhizome fragments spread in dumped vegetation and fill, and by soil movement, flooding, and contaminated machinery.
What damage does it do?
Dense rhizome beds replace all other species, and are shallow rooted, so when they become heavy with rain they can slip on steep sites and streambanks, causing erosion. Succeeded only by weedy vines.
Which habitats is it likely to invade?
Most habitats except dry rocky areas: damp forest and margins, streamsides, river systems, shrublands, fernland, and inshore islands. It is frost-tender but grows under canopy in cool forests.
What can I do to get rid of it?
Plants in deep shade produce few or no seed, so begin control on margins to minimise reseeding.
1. Cut down and paint stump (all year round): cut above pink 'collar' at base and apply picloram gel or glyphosate (250ml/L) or metsulfuron-methyl 600g/kg (1g /L) or metsulferon gel. Leave stems and leaves on site to rot down.
2. Dig or pull out small plants (all year round). Don't compost, leave on site to rot down or hang rhizomes in trees, as they survive indefinitely. Dispose of rhizomes at a refuse transfer station or by drying out and burning.
3. Spray (all year round): metsulfuron-methyl 600g/kg (5g/10L knapsack). Add penetrant in winter. For dense patches keep spray away from roots of vulnerable plants. Don't replant sprayed sites for 6 months.
What can I do to stop it coming back?
Seeds survive for 2-4 years so it is possible to eliminate this plant from sites. Maintain rolling front and check for seedlings annually.