Astilboides tabularis (a.k.a. Shieldleaf) is one of the most attention-grabbing shade plants in the garden - as long as it gets LOTS of water.... I have two groupings of it - one has water delivered to it by one of our downspouts from the eavestroughs as well as water from one of the next-door-neighbour's downspouts. The other batch of astilboides is under the edge of the red oak tree canopy and only gets water from direct rainfall and runoff from higher up the slight slope it's on. It also gets a bit less light than the ones in the north alley, but I think water is the relevant issue. These two pictures, taken this morning, show the substantial difference in size:
Getting lots of water (plenty of room for Cole to explore under there!):
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Getting considerably less water:
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I really need to move these ones to damper conditions next spring!

Astilboides used to be classified as a Rodgersia, another of my favorite big-leafed plants. Rodgersia is said to like moist conditions as well so I planted some with the astilboides. Interestingly, while they grow well in the same conditions, the ones with the biggest leaves in my garden are in dryer conditions in deeper shade under the edge of a canopy of white pines!

Rodgersia beside astilboides:
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Rodgersia under white pines:
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Both astilboides and rodgersia are very well behaved for me - i.e. they are not vigorous spreaders like some of the big-leafed moisture-loving plants. So these are wonderful plants to add to the shade garden if you have the coonditions for them.