Host: Myoporum laetuon Forst. f. On branches, trunks, petioles, inflorescences, and drupes. Herb. Nos. 404, 777. Palmerston North (Wellington), 250 m., G. H. C. Feb., May, Dec., 1921; Feb., May, 1922. (Type.) Woodside Creek, Wharanui (Marlborough), E. H. Atkinson! 3 Nov., 1922.

0. Unknown.
I. Aecidia caulicolous, truncicolous, petiolicolous, and on inflorescences and drupes, seated on inflated fusiform areas up to 15 cm. long, crowded in linear groups, orange. Peridia erumpent, cylindrical, standing above the surface about 4 mm., 1 mm. diam., margins slightly expanded but not revolute, deeply and irregularly lacerate, tinted orange, bleaching white with age. Spores obovate, elliptical, irregularly polygonal or less commonly lachryiniform, 21-45 X 17-20 mmm.; epispore hyaline, finely and closely verruculose, 1 mmm. thick, cell-contents reddish-orange, germ-pores indistinct.

0. Incognitis. I. Aecidiis caulicoliis, truncicohis et petiolicolis, in locis inflatis fusiformibus, ad 15 cm. longis, in catervis linearibus, aurantiacis. Peridiis erumpentibus, cylindricis, super superficiem exstitis ad 4 mm., 1 mm. latis, marginibus subtiliter expansis non revolutis, profunde inaequalibus laceratis, cinctis aurantiacis, demum albis. Aecidiosporis obovatis, ellipticis, polygoniis, raro lacrimiformibus, 21-45 X 17-20 mmm.; episporio hyalino, subtiliter solide verruculoso, 1 mmm. crasso, contentu rubescente-luteo, foramine germinis obscuro.

The host is, endemic, and is widespread. (Cheeseman, 1906, p. 563.) This species forms large fusiform swellings on the branches of the host; as a rule it occurs on laterals, forming "witch's-brooms," but it is not confined to these, as I have collected it on large trunks 30 cm. in diameter. The peridia resemble those of the form-genus Roestelia, but only in size and shape, for they dehisce apically and not throughout their length; more-over, the spores are characteristic of Aecidium, the epispore being hyaline and minutely verruculose, and the germ-pores are indistinct. The spores vary considerably in size and shape; the measurements given above are taken from average spores, for if the lachrymiform ones were measured they would give an entirely erroneous impression as to the average size, they being more than twice as long as the average spores.
It is probable that the mycelium is perennial, as the fungus may be obtained throughout the year from infected plants.

Hab. : In caulibusque, trunci, et petiolibusque Myopori laeti Forst. f. Palmerston North, Wellington, New Zealand, 250 m. G. H. C.

This endemic rust fungus is associated with fusiform stem cankers. Cunningham (1931a) described them as "witches brooms"; originally it was described only from the endemic Myoporum laetum, but recently it has been found infecting the Australian species M. acuminatum. It is not uncommon in Hawke's Bay and Wellington in the North Island and Marlborough in the South Island and may cause minor damage, especially when Myoporum is used for shelter hedges.

Type: Rust and Smut Fungi; Description: Aecia scattered in large numbers, minute, cylindrical, tube-like, yellow or white, up to 4 mm tall, 1 mm wide, bearing distinctive golden yellow masses of aeciospores, on elongated, spindle-shaped, cankerous swellings, up to 15 cm long; on living shoots or on leaf or flower stalks. Aeciospores obovate to elliptical, 21–45 × 17–20 μm, hyaline, finely and closely verruculose, golden yellow.

Distribution: Auckland, Waikato, Wellington, Gisborne, Hawkes Bay, Marlborough.; 1st Record: Cunningham (1924a).

Significance: Although spectacular, this rust appears to cause little damage.; Host(s): Myoporum acuminatum, M. laetum.