With a blue bandanna tucked under his hat and draped across his neck to protect him from the sun, Gordon Fidler of Palm Desert walked slowly over the terrain at Joshua Tree National Park, eyes peeled for tumble mustard – a weed invading an area of Keys View and threatening the natural wildlife. … Invasive plants – or weeds – create fire hazards, crowd out native plants and consume water and nutrients, depleting food sources for the habitat such as the desert tortoise.