After the spring rains at Pipestone National Monument, pools can found in shallow depressions on the bedrock surface. These low areas accumulate rainwater, forming ephemeral pools. These seasonal pools support a surprising diversity of aquatic plants. Only a few pools on any outcrop are deep enough to last a few weeks but not so deep that permanent wetland vegetation can take over. Minnesota has about 15 rare plant species limited to these bedrock pools. Many of these exist submerged and will not flower until they are stranded in moist mud after the pools evaporate. Once stranded, they morph into upright plants with more rigid leaves that last for a couple of weeks. The plants vanish as the sun quickly bakes the mud into cracked crusts of sediment, to await the next season of heavy rain.
Posted on: Tue, 24 Jun 2014 23:44:51 +0000
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