294 ROCK GARDENS 



loNOPSiDiUM ACAULE (Cruciferae), Violet Cress 



This, though only an annual, may be included, being such a dainty 

 little plant, which, when once established, sows itself, and causes no 

 further trouble. It likes rather a damp spot, and only grows from 

 I to 2 inches high, with small, pale violet-coloured flowers, borne in 

 endless profusion the whole summer. It often comes into flower a 

 couple of months after being sown. One of the very few annuals 

 admissible into the rock garden. 



Iris (Iridaceae) 



A very large genus of plants, wonderfully varied, both in habit 

 and flower. They are mostly too coarse-growing for the rock 

 garden, but a few of the dwarfer kinds are suitable. The following 

 are some of the best : — 



/. arenaria. — Sandy soil in sun. Grows 3 to 4 inches high. 

 Flowers bright yellow, striped purplish-brown. Blooms in 

 May. 



/. cristata. — Light sandy, stony soil on a level spot, in sun. Of 

 dwarf habit, spreading freely by means of rhizomes. Flowers a lovely 

 blue, and of a large size. A beautiful plant, of which the slugs are 

 inordinately fond. 



/. gracipiles. — Requires a partial shady position in fibrous loam, 

 well drained, and plentifully niixed with leaf-mould. A dwarf- 

 growing and very lovely little plant, with clear blue flowers shaded 

 with lilac, borne on slender stems. It is quite hardy and not 

 difficult to grow. 



7. lacustris. — This is a miniature form of /. cristata^ with flowers 

 of rather a deeper shade of blue. It requires similar treatment. A 

 charming and dainty plant. 



/. verna. — Requires sandy peat and shady position. Only grows 

 about 4 inches high. Flowers a rich violet-blue, and sweet- 

 scented. 



Other species suitable for growing in the rock garden, in light 

 soil and sunny position, are — /. alata^ I. apkylla, I. Chamaeiris and 

 its varieties, /. puDiila and its varieties. 



ISOPYRUM THALICTROIDES (RaNUNCULACEAE) 



A graceful and dwarf-growing little plant for a half-shady position 

 in light, rather poor soil. It has greyish-green leaves rather like a 

 maiden-hair fern, and panicles of small white flowers. It is quite 

 hardy, and easily propagated by seed or division. 



