VARIATION IN PHORMIUM-COOKIANUM (AGAVACEAE)

Phormium cookianum contains two well marked geographic forms. one characteristic of lowland parts of the North Island. and the other of southern and mountainous parts of the South Island and the axial ranges in the North Island. They are clearly distinguishable by the colour of the outer tepals, which are green or yellow in the northern-lowland form. and red in the southern-mountain form. Other characters also distinguish them. although not so decisively. Along both shores of Cook Strait, especially near Wellington, there are populations which include both forms and intermediates. Very robust plants in eastern parts of the South Island may reflect introgression with P. tenax. Published names are available for the two forms. Southern plants with red outer tepals fit P. cookianum Le Jolis. while the new combination P. cookianum ssp. hookeri (Gunn ex Hooker f.) Wardle is proposed for northern plants with yellow or green outer tepals. © 1979 Taylor & Francis Group, LLC.