I'm in zone 5 near Boulder/Longmont and am looking for suggestions of perennials to that do well in part sun to shade conditions. Plants that do well near tree roots would be especially great now that our landscaping has matured. I have some hosta that are doing well, a Jacob's Ladder I planted last year that came back, an astilbe (that isn't really thriving), Lady's Mantle, snowdrop anemone, and various groundcover plants. I would especially love some that have a taller, spike-y habit to intermingle with the groundcover and mounding plants. Any favorites shade-loving plants from your garden?