Starch grains and xylem cells of sweet potato (Ipomoea batatas) and bracken (Pteridium esculentum) in archaeological deposits from northern New Zealand

Starch grains and xylem cells found in prehistoric coprolites and a stone mound provide direct evidence for agriculture. Fossil starch and xylem (vessel elements) of introduced sweet potato (Ipomoea batatas) root in a mound at Pouerua suggests these structures were used to cultivate this species. Sweet potato starch and xylem in coprolites from Great Barrier Island provide evidence for cultivation and diet. Fossil starch grains and xylem (tracheids) of bracken rhizome in coprolites from Kohika provide the earliest direct evidence for the use of this native plant in New Zealand as a carbohydrate food source. Analysis of xylem in starch storage organs is a valuable addition to the study of starch preserved in archaeological deposits. (C) 2003 Elsevier Ltd. All rights reserved.