Wednesday, September 28, 2011

In Search of Water

This summer just won't end.  For weeks, since the calender said that fall was approaching (hah!), we've been waiting for an opportunity to get outside for a hike, preferably not in the triple-digit heat.  Finally, last week, with a shared weekday off for our anniversary, Lee and I decided that, running water or not, hot summer day or not, we were just going to have to get out in it.

We went to the Hamilton Pool Preserve, a Travis county park where Hamilton Creek, a tributary of the Pedernales River, flows over a ledge, as a waterfall, into a pool in a limestone grotto below, creating a natural swimming hole.  As one of the last places with running water and reliable swimming in dry summers, Hamilton Pool is very popular on weekend days in the summer and regularly fills to capacity.  Arriving late on a Monday morning, we were looking to miss the crowds and have the trail to ourselves.  We were also hoping that the spring-fed creek would be flowing.

Hamilton Creek was running, though barely so.  A trickle of water fell from the top part of the creek into the pool, which was open for swimming, though the water was a murky green.  We walked around the pool, enjoying the cool air along the back side of the grotto, where rock walls out of reach of the midday sun still held, even at noon, the cool of the evening, then we headed out on the trail to the river.

This was the restorative part of the journey, walking beneath healthy cypress trees with their roots in the creek below.  The creek wasn't running quickly, but it was a couple feet deep in places, with cool water that was still supporting fish and turtles and baby cypress trees.  The presence of water made all the difference, cooling and humidifying, in a pleasant way, the air in the canyon along the creek.  For that short stretch of creek we left the drought that has so defined this summer, the extreme and lasting heat, the dry winds, and the lack of rainfall, in the uplands above.  In this way, the preserve is doing its job, providing a refuge for plants and animals through the roughest months of the year.  And providing me a place to breathe fresh, tree-made oxygen and gaze up into the branches of cypress, Spanish oak, and elm trees still holding onto their green leaves.

Along the trail at ground level, the pink-purple flowers of Simple-Leaf Tick Clover caught my eye.  I knew immediately that the flowers belonged to the Pea Family, but it took me a bit of looking to locate the species.  Tick clovers make attractive pink-purple flowers from May through October but are more commonly known for their annoying seed pods that stick to socks and pant legs in the fall and winter, which is why they are also called Beggar's Ticks.  The Simple-Leaf Tick Clover (Desmodium psilophyllum) is the only species of tick clover in this area that has simple leaves rather than the trifoliate (composed of three leaflets) leaves of other tick clovers.

Simple-Leaf Tick Clover (Desmodium psilophyllum)

Blue Mist-Flower also bloomed along the creek.  Blue Mist-Flower (Eupatorium coelestinum) is a late-summer to fall blooming perennial that is common in moist, shady habitats in central Texas.

Blue Mist-Flower (Eupatorium coelestinum)

As Hamilton Creek and the trail neared the Pedernales River, the canyon widened and the trail climbed away from the creek.  The water of the creek disappeared beneath the sandy creek bed into groundwater, so the creek, though running in the section beneath the pool, did not flow into the Pedernales River.  The river itself was also dried up, with rolling mounds of hot sand left where the river usually flowed.  Lee and I walked along the riverbed, hoping to spot a flowing portion of the river around the next bend, but we didn't get far before the course, sharp grains of sand accumulating between our feet and our Tevas motivated us to step into the warm pools of water, all that remained of the Pedernales river.  As far as we could see in both directions, the river was reduced to intermittent pools, and some of the cypress trees along the river were responding to the drought by turning orange-red, getting ready to drop their leaves two months early.

In a few low spots, the sand was still moist, indicating that the river may have flowed, or at least held more discontinuous pools of water, very recently.  Heat-hardy wildflowers were blooming along the riverbank, making the most of the receding water supply.  Small, pink blooms of Prairie Agalinis hid in a tangle of greenery alongside a tall stand of bright-yellow Tatalencho.  Farther down the bank, a colony of White Boneset bloomed.  White Boneset (Eupatorium serotium), a perennial in the sunflower family, prefers the moist soil along streams, where it blooms from August through October.

White Boneset (Eupatorium serotium)

Clammyweed, a sticky plant in the same family as the plants that produce caper berries and peppercorns, has distinctive flowers with pink to purple stamens that are much longer that the white petals.  Clammyweed (Polanisia dodecandra) is common in dry creek beds, along low-flowing creeks, and on roadsides, blooming May through October.

Clammyweed (Polanisia dodecandra)

The showiest and most abundant flowers along the river bed were the orange-highlighted yellow flowers of the Rattlebush.  Rattlebush (Sesbania drummondii) is a woody shrub that is common along waterways and in dry stream beds in central and east Texas.  The leaves of Rattlebush, like those of many heat-tolerant shrubs in the Pea Family, are compound, composed of many (20 to 50) small leaflets.  The seedpods of Rattlebush, which are are flattened around each seed, remain on the plant into the winter, long after the leaves have fallen from the plant.  The mature seeds are loose in the pods and rattle when shaken by the winds of winter cold fronts, giving the plant its name.  The seeds of Rattlebush are poisonous.

Rattlebush (Sesbania drummondii)

Wanting to escape the bright sun of midday and the sharp sand of the river bed, Lee and I returned, high-stepping to kick sand from our Tevas with every step, to the trail along the creek.  Usually I prefer a loop trail, and the chance to walk down a new section of trail for an entire hike, but this time I was glad to return back along the same short trail, to get another dose of what has been almost entirely missing from my life this summer, walking in the woods along running water.

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