Illustrated with three photographic plates of seeds and several small line drawings, large slim octavo, pp (51), a slight crease to the upper margins throughout, otherwise a very good copy, paperback. SCARCE. Bulletin of the British Museum (NH), Botany, Volume 3 number 4. [From the library of the botanist Eric Groves, with his stamp on both covers.]. {Petrorhagia is a small genus of annual and perennial plants of the family Caryophyllaceae, mostly native to the Mediterranean region. The genus is often referred to as Tunica, which is an obsolete synonym. It is low-growing with wiry stems and narrow, grass-like leaves. The flowers are small, in clusters similar to members of the genus Dianthus, in pink, lilac, or white. Petrorhagia saxifraga is the tunic flower or coat flower, similar to baby's breath, but shorter, and used in rock gardens.}