This pattern is published in Maire Treanor’s excellent book which was originally published in Ireland by Mercier Press in 2002, but has since been republished by Lacis in the US.

Details from Interweave Crochet, Fall 2011

Finished Sizes:
Small Irish Rose: 1¼” across in size 20 thread, 1¾” across in size 10 thread;
Wild Irish Rose: 2½” across in size 20 thread, 4¼” across in size 10 thread.

Yarn: Size 10 or 20 mercerized cotton thread.

Hook Size: 10 (1 mm; for size 20 thread) or size 7 (1.65 mm; for size 10 thread) steel hook. Gauge is not critical for this pattern.