Aston B. C. 1918 (a). Indigenous tans and vegetable dyestuffs of New Zealand. New Zealand Journal of Agriculture 15: 55-62, 117-128
Part I. Historical and Introductory. A thorough literature review of use of dyes by Māori. Referenced. Plants and processes described. Aston noted that "in the majority of cases, the colouring of the fibres was effected by the aid of plants which are known to be extremely rich in tannin or closely allied compounds".
Part II describes modern experience and research in New Zealand tanning and dyes. Evidence points to Coprosma species as the most economic producer of dyestuffs - related to madder, Rubra tinctorum. Other tannin producing plants listed, with references.
Indigenous tans and vegetable dyestuffs of New Zealand