Large clump-forming herbaceous plant to 3 m high. Stout rhizomes, long stems (<2.5 m) massive umbrella-sized leaves (1.2-2 m), 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.
G. manicata may or may not be invasive, however it is very similar in appearance to the very weedy G. tinctoria, which makes identification difficult and can sometimes result in G. tinctoria being sold and/or distributed with the label G. manicata.
This species is included because it is one of the species to be researched in the 2007-2012 Auckland Regional Pest Management Strategy.
Caution: when using any herbicide or pesticide PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.
G. tinctoria is a smaller plant. The inflorescence is shorter and more 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.