Friday, October 7, 2016

Fall Wildflowers Along the Tuolumne

A few days ago, a breezy fall afternoon along the Tuolumne River started out as a birding venture, but ended up as something of a birding bust.  So, naturally, I turned my attention to botany instead.

Narrow Leaf Milkweed (Asclepias fascicularis) is critical for the reproduction of Monarch butterflies;
it is the only plant on which they will lay their eggs, and on which Monarch larvae feed.

The rivers that flow through the Great Central Valley have seen their share of disrespect over the years, to put it mildly, and the Tuolumne is no exception.  It has been dammed extensively, the water used for irrigation of farmland and the generation of hydroelectricity.  Non-native species of fish have been introduced for sport, and the river itself serves as a corridor for the dispersal of non-native and invasive plant species. 

Sadly, it's often harder to play "spot the native plants" than it is to point out the myriad of invasives that have taken root.  (The list includes Tree of Heaven, Common Fig, White Mulberry, Tree Tobacco, Himalayan Blackberry, Milk Thistle, Star Thistle, Purple Loosestrife, Water Hyacinth... to name a few off the top of my head.)  Non-native fish (striped bass, bluegill/perch) and invasive bullfrogs live in the river itself, while aggressive introduced species of birds (European Starling, Eurasian Collared Dove, House Sparrow) populate the surrounding trees, pushing out native species.

Stands of Bur Marigold (Bidens laevis) were thick along the Tuolumne.  So thick, I was beginning to worry that it
might be a non-native species!  But rest assured, it is a native.

The Tuolumne River flows roughly 150 miles from the High Sierra to join the San Joaquin River in the valley (near the San Joaquin River National Wildlife Refuge) before continuing on through the Delta to the San Francisco Bay.  The stretch of river through the Central Valley, through towns such as LeGrange, Waterford and Modesto, is heavily used by fishermen, picnickers, swimmers, boaters... and, sadly, folks who are up to little good.  Unfortunately, lots of people living and recreating along the river translates to lots of garbage and pollution both in and along the river. 

A lovely purple aster, I'm guessing in the genus Erigeron

Often when I'm walking along the river, it's frustrating and difficult to see past the old tires, beer cans, dirty diapers and invasive species.  But a few days ago, looking past the garbage, I discovered a tiny slice of the old Tuolumne, the former unpolluted river which once fed flood plains with its seasonal rise and fall, resulting in the growth of lush riparian woodlands and stands of wildflowers along its banks.

Tarweed (Halocarpha sp.) shines bright amongst the golden grasses of fall, and, as you might guess, smells a bit like tar.

If you visit the Tuolumne River in its lower reaches through the Great Central Valley, take a moment to admire its beauty.  And then, take another moment to pick up a few pieces of trash. 

Vinegarweed (Trichostema lanceolatum) - you guessed it - smells like vinegar.


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