If I was starting a collection of plants for a bog garden or streamside I would look at a collection of different primula.

Primula Species for Water Gardens

• Primula viallii like rich moist soil and produce a scarlet opening to purple spike or pyramid of flower in late spring.
• Primula sieboldii like a damp sheltered position.
• Primula florindae flowers yellow and lasts for several weeks in summer. A must have plant for this location
• Primula Japonica a compact plant for early summer flowering. Try Postfords White or Apple Blossom.
• Primula pulverulenta, aka the candelabra primula. They flower on a leafless stem at varying points like a candelabra. They  can grow 3 feet tall.