The Brodiaea Reserve, where the Colby Trail is located, is the centerpiece of the Glendora Community Conservancy, and is home to the endangered threadleaf brodiaea, Brodiaea filifolia. This endangered species is protected by both the State of California and the Federal Government.
“This trail is riparian in its lower stretch, with specimens of some species much larger than normal. It contains a vernally moist area, possibly with a vernal pool in wet years, as well as a flattish area with native grasslands that includes the ENDANGERED Brodiaea filifolia. The Jepson Manual says that this species is extirpated from Los Angeles County, but this area is proof that at least a small pocket of these plants survives here.”
Not all of the Brodiaea filifolia is found in a vernal pool-type of area, but it's the clay lens that is responsible for the environment favored by these plants. This species blooms from early May into July.
Here is a panel of photos from mid May 2010, including some of the other flowers blooming simultaneously nearby. Click on the thumbnails to see higher-resolution images, 720 x 480 pixels.
Images © 2010-2017 Graham Bothwell.
Thanks to Jane Strong for assistance in identification of plants and flowers. Also thanks to Jane for permission to quote her material from Tom Chester's web page.