Even when not in bloom, silverleaf phacelia packs a visual punch with its bright silvery rosette of leaves. The blooms are fascinating too though - a tall scorpoin-tail shaped inflorescence of small fancy purple flowers that uncurls as the blooms mature. As though those attributes weren't enough, this tough species leaves on harsh dry rocky slopes, seemingly unfased by hot rainless summers. 
 
This is an ideal rock garden species, but you can plant it anywhere sunny with well-draining soil. They are short lived but readily resow from seed, so leave old flower spikes intact until the spring.