Mt Diablo State Park is a large (20,000 acres, or about 31 square miles) park whose centerpiece is 3849-foot Mt Diablo. Someday I will try to hike all the way to the top, a 14-mile round trip hike, but this time I stayed on the lower part of the mountain, below 2400 feet elevation. There are something like 150 miles of hiking trails in the park, so lots of options to choose from! For this hike I decided to do the Mitchell Canyon – Eagle Peak loop, which starts at the Mitchell Canyon Rd entrance, near the park’s headquarters, and passes Deer Flat and Murchio Gap on the way to Eagle Peak, Twin Peaks, and Mitchell Rock. Highlights were the numerous wildflowers, including several first-time sightings (for me), and wonderful views.
The loop is 8.2 miles and includes over 2300 feet of vertical gain. Not surprisingly, the trail passes through several different types of habitat, including woodland, grassland, chaparral, and drier rocky habitat. On the GPS track the orange dot shows the location of the Mitchell Canyon Rd trailhead.
The first two miles follow Mitchell Creek up a canyon, with a gentle climb from about 600 feet to 900 feet elevation. In the creek-side woodland there were numerous wildflowers. The first was elegant clarkia (Clarkia unguiculata), with the initial sighting barely 0.1 mile from the trailhead. By the end of the hike I had observed five different species of clarkia!
Perhaps ½ mile from the trailhead I noticed some sunflower-like flowers that I believe are Mt Diablo helianthella (Helianthella castanea).
I was specifically on the lookout for Mt Diablo fairy lanterns (Calochortus pulchellus), which are endemic to the Mt Diablo area. They are considered rare due to their limited geographic range. I made sure to photograph the first ones I saw, but then I did see quite a few others later in the hike. The bumps are a characteristic of this species.
I also saw some California wild rose (Rosa californica), cow parsnip (Heracleum maximum), poison hemlock (Conium maculatum) with characteristic lacy leaves, and seep monkeyflower (Mimulus guttatus), along with thistle, poppies, Ithuriel’s spear, and sticky monkeyflower. Just past the 2-mile mark there was a bit of blue larkspur and the entrance to a small cave. I decided not to stop to explore the cave. There was also some paintbrush (Castilleja). Near the edge of the wooded area I noticed some more clarkia, this time two-lobed clarkia (Clarkia bilobia).
Nearby there were some red ribbons (Clarkia concinna ssp. either concinna or automixa), another type of clarkia. Note that the petals have three lobes.
As the trail emerged from the woodland the grade began to get steeper, the habitat turned to chaparral, and the flora changed. Shortly the grade became more-or-less 15% on average for the remainder of the hike.
One of the first shrubs I noted was pipestem (Clematis lasiantha), with characteristic and distinctive “hairy balls,” the stage after the blossom stage has finished. Then I noticed some butterfly mariposa lily (Calochortus venustus). I saw these beautiful mariposa lilies off and on until I was almost back at the trailhead.
In a sunnier area I saw a few four-spot clarkia (Clarkia purpurea ssp. quadrivulnera) and small clarkia (Clarkia affinis).
There was also some bush lupine (Lupinus albifrons), coyote mint (Monardella villosa), yarrow, and some manzanita. I am not sure if any of the manzanita was Mt Diablo manzanita (Arctostaphylos auriculata), but it did have relatively silvery-colored leaves. This type of manzanita is endemic to the Mt Diablo area. I also saw a few swallowtail butterflies that did not bother to land and pose for pictures.
About 2.8 miles from the trailhead I saw the first of many clusters of purple Chinese houses (Collinsia heterophylla), generally on the steep uphill side of the trail in some shade.
There was a gorgeous view generally back along Mitchell Canyon, with Mount Zion in the background. (I’m still learning local landmarks, but I think this identification is correct.)
Perhaps ½ mile further I found several wind poppies (Stylomecon heterophylla), a bit of red larkspur (Delphinium nudicaule) and some pale western larkspur (Delphinium hesperium ssp. pallescens).
Around 3.8 miles from the trailhead I arrived at Deer Flat, a little over 2100 feet elevation and the first peak on the elevation profile. Here, hikers who intend to proceed directly to the Mt Diablo Summit continue climbing on Deer Flat Rd. I turned left on Meridian Ridge Rd for a brief 100-foot descent before another climb. Just as I arrived at the bottom of the descent I noticed a deer in the trail ahead of me. It had already stopped and was carefully observing me. I took a picture with the super-zoom on my camera, then started slowly walking closer. In a moment, the deer vanished.
The next 1.7 miles or so I would be hiking above 2000 feet elevation, and there were frequent fantastic views in multiple directions. For example, here is a view generally to the north-northwest along the east leg of the loop, with Twin Peaks clearly visible on the skyline about 1½ miles away.
In this area I was a bit startled to notice pine cones and ferns together at the base of a manzanita plant. At 4.5 miles from the trailhead I reached Murchio Gap, at the very slight depression in the second peak of the elevation profile. Here I turned left on single-track Eagle Peak Trail to begin what many hikers call the fun part of the hike, with steep ascents and descents along steeper hillsides. Actually, because the trail is narrower, steeper, and rockier, it is a good time to pay attention to where you are going!
The reward for more difficult hiking is fantastic views, like this one roughly to the north. Black Diamond Mines Regional Preserve is in the golden hills, with Clayton on the valley floor and Suisun, Grizzly, and Honker Bays behind.
In this upper portion of the trail I saw several plants/wildflowers that are able to survive in the rocky, dry terrain. One was this mystery plant: I think it is some type of sanicle (Sanicula) but I wasn’t able to make a more specific identification. This was a fairly good-sized patch, several feet across but only a few inches high. The silvery leaves looked almost succulent, and the flower heads were yellow and orange-brown.
Another interesting find was some common dudleya (Dudleya cymosa), which is a succulent plant adapted to growing in dry, rocky areas. There are leaves whirling around the stems up to the pale yellow flute-like flowers, and in addition there are base leaves, not shown in the photo, which can be rather complex and beautiful in pattern. I had not seen this type of dudleya before, but I found quite a few plants in this area.
About 5.3 miles from the trailhead I reached Eagle Peak, officially at 2369 feet elevation and (barely) the highest point of the hike. From here it would be almost literally all downhill to the trailhead. An unusual find along the way was a patch of pincushion plants (Navarretia), each spiky head with tiny, brilliant pink blossoms waving on long stems.
There were repeat views north toward Black Diamond Mines Regional Preserve, beyond which at times I could see the big southern Solano County windmill farm in the background. The descent from Eagle Peak is quite steep in places, with the grade averaging 15%. At 6.2 miles from the trailhead Eagle Peak Trail goes right and Mitchell Rock Trail continues straight. Just past this junction the trail passes Twin Peaks, and there is an almost imperceptible rise before resuming the descent.
It is good to remember to look behind, especially when doing a loop or point-to-point hike. There were spectacular views of Mt Diablo from Twin Peaks, at relatively close range. I think that the ridgetop trail near the center of the picture may be Meridian Ridge Rd.
There was chia and chamise, and a few Anna’s hummingbirds zooming around and singing. During the descent I passed a few wildflowers I had not noticed on the outbound part of the loop, including some unusual pale-colored monkeyflower, a bit of phacelia, and a patch of hedgenettle (Stachys). I thought the patterns on the hedgenettle blossoms were especially pretty.
Shortly the trail descended from open chaparral into rolling grassland, with about 1½ miles to go. There were a few more mariposa lilies, elegant clarkia, and an especially large pine cone, almost 1 foot long! A little less than 1 mile from the trailhead the Mitchell Rock Trail approaches Mitchell Rock, with a great view of this outcropping overlooking the canyon.
There is a final left turn on Oak Rd to complete the loop. Near this junction I noticed two wild turkeys walking through the tall grasses. One of them reached a place where the grass wasn’t quite as tall, and I got a clear picture of its head.
Due to the steepness and terrain, this hike was a bit more challenging than the raw distance might indicate. However, both the views and the wildflowers were worth the effort!