Gromwell

This is an uncommon perennial, useful for sunny borders on well-drained, limey soil but not in rock gardens or anywhere else where the creeping runners might invade inaccessibly. The flowers change from purple in bud to rich blue when fully open, and slightly resemble those of gentians. The plant itself looks like a large bushy lithospermum and once carried the name Lithospermum purpurocaerulea. An irrepressible ground-cover plant, it is highly effective for making a weed-proof mat. Interplant with bulbs for an early show.