Field Trips Log
December 2004

Tuesday, 7 December 2004 (Santa Rosa Plateau Ecological Reserve)

I drove down to the Santa Rosa Plateau Ecological Reserve in Riverside County this morning to photograph mission manzanita (Xylococcus bicolor). Tom Chester had notified me that it was quite abundant along the Wiashal (pronounced wee-uh-shawl) Trail, and he was not wrong. This was my first official photographing trip to the Reserve to begin a collection of pictures of SRP plants to be used in the book that Tom envisions.

I had never hiked on this trail before despite numerous visits to the SRP. Formerly called the Multiuse Trail because horses are allowed there, it goes into an area of the Reserve that I was unfamiliar with, heading northeast from the Visitor Center parking area and more or less paralleling Clinton Keith Road before turning south and switchbacking down to its end at Single Oak Way. If you need directions to its terminus in order to arrange a car shuttle, they are given in Tom's plant guide to this trail.

The trail was muddy in places, but it is a nice trail that passes through chamise and hoaryleaf ceanothus 'forests.' The first mission manzanita I saw had flowers that were wilted and faded, and I thought, "Oh no, I'm too late." But its blooming period is supposed to be December through February, so this must have been a very early specimen. Within another few hundred yards there was a second shrub with no blooms on it. I pressed on knowing that Tom had been there only a few days before and had obviously seen prime blooming, and quickly began coming upon large manzanitas in full bloom practically lining the sides of the trail.

I took pictures of the beautiful urn-shaped flowers that range in color from a deep pink to white, and several of the leaves to show the difference between the upper and lower surfaces. Although nothing else was blooming, I also photographed some thick-leaved yerba santa (Eriodictyon crassifolium var. crassifolium), hoaryleaf ceanothus (Ceanothus crassifolius), little redberry (Rhamnus crocea), California sagebrush (Artemisia californica), Torrey's scrub oak (Quercus acutidens), sugarbush (Rhus ovata), and some animal tracks.

Since I had achieved what I wanted and it was cold and threatening to rain again, I turned around after a mile and returned to the car. Tom's plant guide says that beyond the first mile and a half, this is one of the steepest and toughest trails of the Santa Rosa Plateau, and I left that part of it for a more pleasant day.

--------------------------------------------------------------------------------------------------------------- Monday-Tuesday, 13-14 December 2004 (Mt. Wilson Trail and Santa Rosa Plateau)

I got an interesting e-mail from Tom Chester the other day in which he mentioned that he had found rattlesnake weed (Chamaesyce albomarginata) while doing the plant list for the Vista Grande loop at Santa Rosa Plateau Ecological Reserve. He said that "This is still the only Chamaesyce I've observed at the SRP..." and "C. polycarpa... is the most common everywhere else in socal." This got me to thinking about the two taxa and wondering what was the best feature to look for to tell them apart. His comment that small-seeded spurge (Chamaesyce polycarpa) was the most common in Southern California made me wonder whether in fact I have misidentified plants I've seen in various places in the San Gabriels and Santa Monicas. When I was just beginning my botanical education, I learned to identify this common Chamaesyce as rattlesnake weed, since there were pictures of it in Nancy Dales' Santa Monica Mountains book and that was one of the first sources I used to figure out plants. At that time I had no idea that there were other Chamaesyces that were so similar, so whenever I saw something that looked like it, I just assumed it was rattlesnake weed. A dangerous practise I'm now aware. I knew that the closest place to my house where I had seen what I thought was rattlesnake weed was the Mt. Wilson Trail, so I headed up there Monday morning.

You don't have to go very far before patches of it begin to appear on the sandy edges of the trail. I collected a sample and headed back to the house to look at it under the microscope. Tom had explained to me (and I had confirmed this by reading the keys and species descriptions in the Jepson Manual and Munz's Flora) that C. polycarpa has two pairs of stipules at each node, one on top of the prostrate stem, and one beneath, at least the dorsal pair separate and mostly ciliate, while C. albomarginata has pairs of glabrous stipules that are fused into a single membranous and somewhat fringed scale. It also appears that whereas polycarpa can be either more or less glabrous or hairy, albomarginata is supposed to be entirely glabrous. I was completely shocked when I peered through the microscope eyepiece to find the Mt. Wilson sample to be extremely hairy and possessing unfused stipules, thereby revealing that what I had always told my wife was rattlesnake weed is in fact small-seeded spurge. I realized immediately that all such identifications I have made of this species are at least now suspect.

I wanted as soon as possible to see actual rattlesnake weed, so I drove down to Santa Rosa Plateau on Tuesday morning and hiked what Tom has dubbed the Vista Grande Loop, which consists of parts of the Granite Loop trail, Vista Grande Trail, Monument Hill Rd, Fault Rd, and Waterline Rd. It was a beautiful day and the Reserve was almost empty. Red-tailed hawks circled overhead and harriers skimmed the grassy slopes. I set my GPS so I could easily find the Chamaesyce, but what I found first and which I was very pleased about was California maidenhair fern (Adiantum jordanii) which I have been seeking for some time. It was at the base of some rocks just past the Cole Creek crossing. There was also some California lace fern (Aspidotis californica) in the same location. I have discovered that there is another species of Adiantum in Southern California, aleuticum, which has Rancho Santa Ana vouchers for Santa Anita Canyon, Eaton Canyon and Fern Canyon, which are near to me and where I will look for it next month.

It's interesting that as in so many places like this, most people's exposure to the Santa Rosa Plateau involves those areas that are either closest to the Visitor Center or to a road. So here, probably 90% of the visitors walk the Granite Loop Trail or the trail to the Vernal Pools and miss the rest of the Reserve. I think that once you get out on the Vista Grande Trail, especially as it goes up over the hill from Waterline Rd into the "back-
country", or beyond the Vernal Pools and the Adobes onto the Punta Mesa Trail, you are treated to the best of the Reserve. Turning left on Monument Hill Rd, I noticed some blooming two-tone everlasting (Gnaphalium bicolor) and then found some small patches of the Chamaesyce right where my GPS indicated it should be. I knew it wouldn't be blooming because of what Tom had told me, but even through the hand lens it was obvious that this was very different from the C. polycarpa on the Mt. Wilson Trail. Very glabrous in all its parts, it had very distinctive wide and whitish scales at each node that were the fused stipules. I attempted to photograph it but knew that I would probably have better luck under more controlled conditions at home. I also plan to purchase after Christmas a digital microscope with a built in camera that will be able to capture images at 40x and 100x (and higher) magnification and feed them directly onto my computer screen, and this is what I have needed for a long time to take quality photographs of very small structures. Anyway, I collected a few samples and then enjoyed the rest of my walk. It's obvious that I'm going to have to look closely at these Chamaesyces from now on and not just assume that they are all rattlesnake weed.

When I got home, I took a picture of a single stipule with the leaves and the rest of the stem cut off just to show what it looks like, and even though the photo was taken through a hand lens, it turned out reasonably well and may be viewed here. The picture also shows a slightish white margin to the leaf, which is supposed to be another identifying characteristic, although the margins of most of the leaves on my sample had aged to a dull reddish color.

This will be my final outing and log for 2004, as I am leaving in a couple of days to go back to Virginia to spend Christmas with my wife's family. Happy holidays and best wishes for the New Year!