Friday, September 7, 2012

A Peek at the Creek

En route to one of the remote prairie openings, I stopped to check out activity in the dry creek bed.  A dense morning fog had left everything dripping with water, so the rocks wore a sheen of moisture that masked the true dryness of their situation. 

The pools have been dry for many weeks.  It sometimes seems that the creek has forgotten how to be a creek.

Holes around the base of the largest rocks show where some aquatic creatures went to avoid dehydration.  Crayfish are the most active excavators, but many other organisms take advantage of the security of the burrows.

The gravel bars and rock piles are home to many plants that require a more constant supply of moisture.  They normally grow, flower and set seed during the summer or early autumn when the water level is down and the chances of flooding are minimal.  Even in a dry year there’s some water to be found deep beneath the creek bed.

At Blue Jay Barrens, Sneezeweed, Helenium autumnale, is found growing only in the creek bed.  This perennial plant is most commonly found in silt deposits held in place by bedrock slabs.  Young plants are found growing in loose gravel deposits, but these plants are lost when flood water rearranges the creek channel.

The bright yellow flower heads add a lot of color to the late season creek channel. 

Great Lobelia typically grows at the edge of the channel or as high up as the top of the bank.

This plant has sent its roots down a fissure in a large slab of bedrock.  In order for perennial plants to persist in the creek channel, they must become established in a secure substrate.  I don’t think this root system is in any danger of being washed away.

Crooked-stemmed Aster is another plant that doesn’t get far from the creek.  This perennial species spreads by way of rhizomes and is often found on temporary gravel bars.  I believe that bits of rhizome are carried by the flood water and buried by the gravel.  This gets the plant off to a good start that allows it to flower in its first year of growth.  It’s also able to develop a new system of rhizomes that are distributed during the next flood.

It’s not uncommon to encounter Beggar Ticks along the creek.  This is an annual species with seeds that are easily carried by animals and water.

The Beggar Ticks flower head does not produce any rays, so it’s rather hard to notice.  The seed is contained within an achene that bears two barbed projections that attach to animal fur and people’s clothing.  I think more people are familiar with the seed than they are with the plant.

Hog Peanut produces a rambling vine that is often the dominant ground cover in the woods along the creek.  I rarely see it growing in the creek bed, but that’s where it seems to be doing best this year.

Boneset, Eupatorium perfoliatum, is a species I’ve never before seen in the creek channel.  It’s common in the floodplain where the soils normally retain some moisture, but I don’t think it does well in situations where the soil is saturated for long periods of time.

This species is easily identified by the bonding of the opposite leaf bases to form a single leaf through which the stem passes.  The other species of this genus are a bit more difficult to separate.

The plant is growing with a decided lean.  It was most likely redirected by one of the strong wind storms we’ve had recently.  Maybe it’s just trying to orient itself in the same direction as some of the wacky bedrock layers in this part of the creek.

No comments:

Post a Comment