Bonny Doon Ecological Reserve is a small (552 acres, a bit under 1 square mile) reserve managed by the California Department of Fish and Wildlife in Santa Cruz County, in the Santa Cruz Mountains. The reserve protects one of only a few areas of a unique habitat referred to as the Santa Cruz Sandhills, which are covered with outcrops of Zayante soil. This special soil evolved from sediment from a 15 million year old former. The soil is coarse sand and incorporates a variety of marine fossils.
I learned about the reserve in the context of its unique flora and fauna. Because the soil is low in water content and nutrients, the ecosystem is distinct from the surrounding typical moisture-loving coastal redwood and mixed evergreen forest. Two endemic subsystems include sand chaparral, with shrubs including manzanita, and so-called sand parkland, with sparse stands of ponderosa pines and an understory that includes native wildflowers. The Santa Cruz Sandhills are home to at least four plant species and three animal species that are endemic: found only there.
Intrigued, I created an opportunity to visit. There are a few trails, all of which emanate from a single entry point into the reserve. Off-trail exploration that could damage sensitive plants and animals is discouraged. Across the road from the entry point there is a modest staging area with a small map of the reserve. Portions of the reserve were damaged in the 2008 Martin Fire, and the reserve re-opened in 2009. It is only open to walkers.
It was easy to find the trail entry point at a small break in the modest barbed-wire type fence along the side of the road. Immediately upon entering the reserve the sandy trail passes through chaparral, with wildflowers in evidence. An immediate highlight was a low-growing plant with clusters of small pink flowers: Ben Lomond spineflower (Chorizanthe pungens var. hartwegiana), one of the plants endemic to the very localized area and habitat. For this reason the Ben Lomond spineflower is listed as federally endangered and as rare, threatened, or endangered in California. Within the reserve it is common, and I think it is very pretty.
The GPS track shows an overview of my exploration of Bonny Doon Ecological Reserve; the orange dot shows the location of the staging area across the road. Within feet a trail splits off to the right, to the south. I decided I would explore the northern portion of the reserve first, so I continued straight for about 0.2 mile to a T intersection, where I initially turned left. It is my understanding that volunteers help keep the (informal) trails sufficiently open for walking, but in three locations on the eastern part of the reserve I turned around when it became difficult to continue due to branches or simply thick growth across the trail; this was after the trail left sand chaparral and entered sand parkland. After that I explored in the southwestern portion of the reserve, with my turnaround points determined to some extent by time considerations.
My entire hike was only about 5 miles but took me over 4 hours. This was mainly due to stopping to admire and/or take photographs. My walking pace was also slower on the parts of the trail that were very sandy. The elevation gain/loss was quite modest, about 600 feet.
A very common plant in the reserve is peak rushrose (Helianthemum scoparium), a small shrub that grows in sandy areas, generally in hills or low mountains. The flowers are bright yellow with five petals. Like the Ben Lomond spineflower, this was a first-time observation for me.
Another common plant is yerba santa (Eriodictyon californicum). I have seen yerba santa in a variety of other places, mostly if not always in dry conditions.
According to one description of the reserve, Bonny Doon manzanita (Arctostaphylos silvicola), or silverleaf manzanita, is the dominant plant of sand chaparral. I saw quite a bit of manzanita during my walk, and I presume it was all this species, which is another of the four plants endemic to the local area. From a distance it looks generally like many other medium-sized manzanitas, though the leaves are more of a silvery-grey color.
Yet another early find, also found throughout the reserve, was bush poppy (Dendromecon rigida). This is a shrub with bright yellow flowers that certainly look like poppies, e.g. they have 4 petals.
I took a very short detour on an informal side trail, and just as I was ready to turn around I found a cluster of spiky plants less than 12” tall. I think it is everlasting nest straw (Stylocline gnaphaloides), or possibly California cottonrose (Logfia filaginoides). I’ve never seen either one before, so I am not positive about the identification. Both of these plants are listed on the iNaturalist site for the reserve.
In addition to new finds, in the first part of the trail I also saw more common wildflowers, including blue dicks (Dichelestemma capitatum), common yarrow (Achillea millefolium), and yellow sticky monkeyflower (Mimulus auranticus).
All of these observations were made before I had reached the T intersection barely 0.2 miles into my hike. It took me almost a half hour to get that far!
This is a typical view of the trail in the sand chaparral area. The sand was sufficiently deep that walking required a surprising amount of effort. I had brought – and I used – hiking poles to help make walking a bit easier. The hill in the background is in the far north of the reserve in an area that is closed to the public.
After turning left at the T intersection I walked generally north, then east, climbing about 100 feet before turning around. In this section of trail I found one, or possibly two, species of paintbrush (Castilleja sp) and even some ferns that seemed happy to grow in the sunny, sandy, and dry habitat. In addition, I found some wartleaf ceanothus (Ceanothus papillosus). The species name papillosus is in reference to the knobby structure or texture of the leaves. Similar to other ceanothus, the individual blossoms are quite small, only a couple of mm across.
An interesting find was some horkelia, I believe either wedgeleaf horkelia (Horkelia cuneate) or Point Reyes horkelia (H. marinensis); both are on the iNaturalist list for Bonny Doon. The leaves, in another photo, look somewhat more like Point Reyes horkelia, but not quite like any of the pictures on the Calflora site.
I was particularly on the lookout for Santa Cruz wallflower (Erysimum teretifolium) but did not find it. Instead, I found quite a few of another type of wildflower with clusters of yellow flowers on a long stem. These “mystery” flowers appear to be composites, with 5 pairs of ray flowers and numerous disc flowers in the center. If you look closely at the picture you can see distinctive structures within the disc flowers, each with a pair of circular loops on a single stalk. (I’m not using proper botanical vocabulary here.) The Santa Cruz wallflower is yellow but, like other wallflowers, is not a composite and has 4 petals.
Update: While researching a very similar flower observed on another hike I have concluded that this is probably seaside golden yarrow (Eriophyllum staechadifolium), sometimes called lizard tail, or possibly golden yarrow (E. confertiflorum).
Finally, in the sand chaparral I found, among Ben Lomond spineflowers, an example of variable linanthus (Leptosiphon parviflorus). This small flower is usually white, but is occasionally yellow.
Particularly in the sand chaparral part of the reserve, there is ample evidence of the 2008 Martin Fire. Although to me the chaparral itself looks like it has recovered nicely, perhaps even fully, there are numerous charred trees that serve as a reminder of the fire. The fire started within the reserve and is thought to have been started by trespassers in the off-limits northern area.
After returning to the T intersection I continued to the southeast into a sand parkland area, where the trail passed through much denser chaparral, with a mixture of trees. In some areas the trail was barely wide enough for me to walk comfortably without worrying too much about what types of plants I was brushing against.
Some of the trees in this area include Douglas fir, ponderosa pine, which is common in the Sierras but uncommon near the coast, a few types of oak, and coastal redwood. There was a group of taller trees that towered above the surrounding forest.
In the northern area of the preserve I found a tarweed, possibly grassy tarweed (Madia gracilis), or woodland madia (Anisocarpus madioides) – these two wildflowers look quite similar, so I might be missing another characteristic that would distinguish them. I also found California everlasting (Pseudognaphalium californicum) and chaparral pea (Pickeringi montana). At a moment when I was dealing with my hiking poles and camera on the narrow clear portion of the trail, I managed to knock my GPS unit off my waist pack and onto the ground. By the time I noticed it and raced back to find it, it turned into a 20-minute detour and nearly a mile of extra hiking that is not included in my hiking distance.
In any case, after exploring the trail further and encountering essentially-blocked trails, I retraced my original path back to the side trail nearly at the beginning of my hike. Instead of completing a loop as originally planned, I hiked south from the entry point, initially near the road. After about 0.2 mile and crossing a dirt road I came to a Y intersection, where I initially took the left fork. I proceeded about 0.5 mile, slightly past a small creek crossing, where I found some western azalea (Rhododendron occidetale). The blossoms have beautiful yellow markings and long reproductive parts that extend well past the petals.
There were several other moisture-loving plants nearby, including common monkeyflower (Mimulus guttatus), a type of hedgenettle, and pink honeysuckle (Lonicera hispidula). There was also a quite pretty flower with a striking long lower petal. Although not showing clearly in this picture, there were a few darker spots deep in the throat of the flower.
I had thought the two paths from the Y might form a loop I could hike around. However, after photographing the white wildflower I decided to return to the Y and explore the other branch of the trail. I only covered about 0.3 mile on this trail before returning to the trailhead due to a time constraint. Along the way I heard, and then saw, a spotted towhee (Pipilo maculatus) about 15 feet up in a tree perhaps 10 meters off the trail. My best picture is still a bit grainy due to the extreme zoom I needed to use, but it’s good enough for the identification.
This section of trail also passed close to a tiny creek where there were moisture-loving plants. I was startled to suddenly see both purple and white forms of purple foxglove (Digitalis purpurea). Although the plants are poisonous the flowers are quite pretty, with lovely purple spots on the inside of the petals.
After this sighting I returned to the trailhead, with a California poppy and a few lupines along the way.
When I planned my visit to Bonny Doon Ecological Reserve I had targeted the four plants that are endemic to the Santa Cruz Sandhills, along with two others that are only slightly more widespread in the Santa Cruz Mountains. Of my six target plants I only saw two: Bonny Doon manzanita and Ben Lomond spineflower. Perhaps another time I will be able to find Santa Cruz wallflower, Ben Lomond buckwheat, Santa Cruz cypress, and Santa Cruz monkeyflower. It would certainly be fun to try!