Hosts : Linum monogynum Forst. On leaves and stems. Herb. Nos. 241, 297. II. York Bay (Wellington), E. H. Atkinson ! 24 Oct., 1920. II, III. Seashore, Seatoun (Wellington), E. H. Atkinson! 27 Jan., 1921. Linum monogynum Forst. var. chathamicum Cockayne. II. York Bay (Wellington), E. H. Atkinson ! 23 Jan., 1921.

0. Spermogones amphigenous, numerous, scattered, immersed, inconspicuous.
I. Caeomata amphigenous, chiefly hypophyllous, scattered, orbicular, 0.2-0.5 mm. diam., orange, pulverulent, surrounded by the ruptured epidermis. Spores subglobose, 20-28 mmm. diam.; epispore hyaline, finely and closely verruculose, 1 mmm: thick, cell-contents vacuolate, yellow.
II. Uredosori amphigenous and caulicolous, scattered or crowded, orbicular, 0.5 mm. diam., on stems elliptical and up to 2 mm. long, pulvinate, pulverulent, surrounded by the ruptured epidermis; mixed with numerous incurved, hyaline, capitate paraphyses. Spores subglobose, obovate or broadly. elliptical, 18-24 X 14-18 mmm.; epispore hyaline, closely and finely verruculose, 2 mmm. thick; germ-pores equatorial, obscure.
III. Teleutosori amphigenous and caulicolous, scattered or crowded, often confluent and up to 8 mm. long, irregular, discoid, reddish-brown, becoming shining-black, long covered. Spores laterally compacted, subepidermal, prismatic, unicellular, 40-55 X 9-15 mmm.; apex obtusely rounded or truncate, slightly (3 mmm.) or not thickened, base truncate; epispore smooth, brown, 1 mmm. thick; germ-pore obscure, apical.

Distribution: Europe; North and South America; Australia.

Both hosts are endemic; they are especially abundant along the sea-coasts. (Cheeseman, 1906, p. 86.)
The uredosori are common, and are conspicuous owing to their bright orange colour. The teleutosori appear to be rare here, as only a few sori have been found on the abundant material in hand.

This European rust species is recorded in New Zealand on the cultigen L. usitatissimum, on the introduced Australian weed species L. marginale, and on the endemic species L. monogynum. In a study of resistance of linen flax and linseed to rust, Cruickshank (1950) noted that Cunningham, as a result of a survey carried out in 1943-44, stated that rust was the most serious disease in New Zealand on linen flax. During World War II autumn and spring sowing of crops was introduced, and rust became widespread in these crops. Cruickshank (1951 a, 1952b), Cruickshank and Wright (1953), and Steveninck and Cruickshank (1956) noted the rust races present in New Zealand and listed resistant varieties of linseed and linen flax.