Large clump-forming herbaceous plant to 2 m high. Stout rhizomes, massive umbrella-sized leaves, which along with stems are covered in rubbery prickles. Overall the plant resembles a giant rhubarb. In summer, tiny green flowers are formed on a spike up to 1 m long. Flowers are followed by tiny fruit.
Terrestrial. Almost anywhere in NZ with moderate light.
Seed spread by birds and water. Rhizomes by deliberate plantings, soil movement.
Forms dense colonies and displaces native vegetation.
1. Dig up entire plant and dispose of all material. Mulch or compost leaves but seed heads and rhizomes better deeply buried. Entire rhizome must be removed because small pieces of live rhizome can resprout. Hand pull seedlings.
2. Cut and paint over half the leaf stems & all of the flower/seed heads with Vigilant gel.
3. Spray with herbicide (100ml glyphosate + 20ml penetrant/10L).
Caution: when using any herbicide or pesticide PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.
G. manicata is a larger plant. The inflorescence is longer and less compact. Another difference is between scales which are found at the base of the leaves and inflorescence. In G. manicata there is a prominent development of membranous "webbing" between the main lobes of the scale whereas in G. tinctoria this is not well developed and so the lobes are often almost free to the main rachis of the scale.