Hosts: Caltha novae-zelandiae Hook. f.
Sebastopol Range, Mt. Cook, Canterbury, 1,300 m., 1/28 G.H.C. Type. Craigieburn Range, Canterbury, 1,500 m., 1/28. H. H. Allan! Alecs' Knob, Franz Josef Glacier, Westland, 1,300 m., 1/28. G.H.C. Caltha obtusa Cheesem. Mt. Rangitaipo, Westland, 1,200 m., 2/28. G.H.C.

0. Unknown.
I. Aecidia hypophyllous, yellowish, scattered evenly over the leaf surface, occasionally on petioles, not distorting; peridia 0.3-0.5 mm. diam., slightly erumpent, margins only showing above the inflated epidermis, scarcely reflexed, white, toothed; spores shortly elliptical, subglobose, seldom polygonal, 18-22 mmm. diam. ; epispore hyaline, 1 mmm. thick, densely and minutely verruculose.

Both hosts are endemic and fairly widely distributed (Cheesem. 1925, p. 454-455).
The mycelium of this rust is systemic, etiolating the leaves and dwarfing the plant, and on this account rendering it conspicuous. Sometimes the aecidia parallel the mid-rib, forming lines of a few aecidia on either side.
Owing to the imperfect descriptions published elsewhere, and to. the absence of specimens, it is not possible to identify this species with any other rust occurring on Caltha; the sorus characters separate it from a plant McAlpine (1906) has provisionally named. Aecidium Calthae Grev. (the aeeidial stage of Puccinia Calthae Link), and its systemic habit is a feature not recorded for other species. occurring on the same host.genus. In view of these facts it is provisionally named as new until such time as the teleutospores have been collected.

This endemic rust causes leaf and stem distortions in the endemic alpine species of Caltha. It occurs in both the North and South Islands.