A Maori group has lodged a claim for the commercial rights to three varieties of kumara, and demands "the varieties of kumara in Aotearoa be restored to the control of Maori".
The claim to the Waitangi Tribunal is one of a number being heard in Wellington this week relating to the Wai 262 Flora and Fauna claim.
The group says the Crown breached the Treaty by failing to preserve pre-European kumara varieties, and deliberately allowed the last remaining stocks to be lost to overseas collections.
The group is seeking "the varieties of kumara in Aotearoa be restored to the control of Maori" and full commercial rights to the hutihuti, rekamaroa and taputini varieties - a smaller kumara with white skin and flesh.
However, the claim was yesterday thrown into doubt by the testimony of Crown witness and historian Dr Ashley Gould.
He said it was unlikely that the original kumara variety brought to the country by Maori about 1000 years ago still survived. He said the popularity of the new higher yielding varieties, introduced probably by American whalers in the early 19th century, began the demise of the ancient stocks.
The new varieties soon replaced the smaller variety of Maori kumara.
Dr Gould said doubt remained about the purity of at least two of the three varieties claimed by Maori.
He said the mericana, or kaipakeha, a sweet potato introduced in the mid-1800s, had similar characteristics to the hutihuti and rekamaroa. In the 1860s the waina variety was introduced with its distinctive red skin and yellow or cream flesh.
The waina was thought to have spawned varieties including the owairaka red, the most common commercial crop today.
"In my view, rekamaroa and, in probability, the ... hutihuti, are not survivals of pre-contact varieties." New Zealand's commercial crop centres around three varieties, the beauregard, a recent import, the toka toka gold, a 19th-century import, and the owairaka red. "There is no link between commercial lines and any varieties assumed to have been present in New Zealand pre-contact," Dr Gould said.
"Late 19th-century observers were clear ... new varieties of kumara and the impact of the potato on the Maori economy, saw the probable disappearance of most, if not all, the pre-contact varieties."
Dell Wihongi, a leading figure in the claim, said the hutihuti, rekamaroa and taputini were the last remaining varieties of the indigenous crop, and it was important Maori were recognised as guardians.
Ms Wihongi is a member of Te Pu Hao Rangi Trust, guardians of the early kumara, involved in a joint venture with Tahuri Whenua Inc, the National Maori Vegetable Growers Collective, to explore the economic potential of the early kumara.
The WAI 262 claim before the tribunal seeks exclusive and comprehensive rights to indigenous flora and fauna as well as all Maori cultural knowledge, customs and practices. It is a mammoth claim that began in 1991. Closing submissions from both sides are expected by the end of March.
The Sweetest Potato
* The kumara was domesticated in central and northern South America around 10,000 years ago.
* Around 5000 varieties are said to exist.
* It is still unclear how the kumara was introduced to the Pacific.