Hosts : Clematis indivisa Willd. On leaves, stems; petioles, and sepals Herb. Nos. 188, 434. Lake Horowhenua, Levin (Wellington), 30 m., E. H. Atkinson ! 26 Oct., 1919. Peel Forest (Canterbury), H. H. Allan ! 8 Nov., 1919. Manawatu Gorge (Wellington), 150 m., J.W. Whelan ! 29 Sept., 1921. Putara, Eketahuna (Wairarapa), H. Watson! 8 Nov., 1921. Clematis Colensoi Hook. f. On stems and petioles. Herb. No. 231. Miramar (Wellington), 20 m., J. W. Bird! 5 Nov., 1920.

0. Spermogones associated with the aecidia, immersed, honey-coloured.
I. Aecidia amphigenous; caulicolous, petiolicolous and sepalicolous, crowded in inflated distorted areas which may attain a length of 15 cm., orange. Peridia cupulate, shortly erumpent, 0.5-1 mm. diam., margins revolute, yellow, deeply and irregularly lacerate. Spores globose or polygonal, 23-36 mmm. diam.; epispore hyaline, delicately and closely verruculose, 0.75 mmm. thick, cell-contents granular, orange.

Distribution: Endemic; common throughout.

The hosts are endemic, and are abundant throughout. (Cheeseman, 1906, pp. 2, 3.)
This rust forms conspicuous distorted areas, many centimetres long, on the stems and leaves of the hosts. The mycelium is perennial, so that once a plant has become infected the rust appears season after season. The specimens on Clematis Colensoi are badly infected with Tuberculina persicina (Ditm.) Sacc. (see Appendix, p. 50). Lindsay records the rust upon Clematis hexasepala DC.
The aecidia of this species are formed within the host-tissues in the vicinity of the phloem, and all stages may be obtained from immature to fully-developed peridia containing numerous spores. As they develop, the peridia move towards the periphery of the stem, and prior to dehiscence may be found fully developed lying beneath the epidermis. That they are mature is evidenced by the behaviour of the spores, for on being placed in water these give rise to infection hyphae.

The rust was described by Lindsay (1867) from "C. hexasepala". Kirk (1908) recorded it on cultivated plants of some of the indigenous species. Cunningham (1931a) noted that the type is no longer in existence and that it has not since been collected on this host. It causes considerable distortion to stems, petioles, leaves, and dowers on indigenous species of Clematis. It is common throughout New Zealand.

Type: Rust and Smut Fungi; Description: Aecia densely scattered, cup-shaped, barely erumpent, orange, with an irregularly torn margin, up to 1 mm in diameter; on distorted, inflated swellings, up to 15 cm long, on leaves, petioles, sepals, and stems. Aeciospores globose or polygonal, 22–30 × 20–25 μm, delicately verruculose.

Distribution: Auckland, Coromandel, Bay of Plenty, Nelson, Marlborough, North Canterbury, Otago Lakes, Southland, Stewart Island.; 1st Record: Lindsay (1867).

Significance: The rust causes little damage.; Host(s): Clematis afoliata, C. foetida, C. forsteri, C. marata, C. paniculata.