Plant Field Reports, Desert Outside San Diego County, 2008

Table of Contents

11 February 2008: Joshua Tree National Park: Red Butte Wash and Cottonwood Entrance Road

16 February 2008: Whitewater Canyon / Joshua Tree National Park: Red Butte and Carey's Castle Wash


11 February 2008: Joshua Tree National Park: Red Butte Wash and Cottonwood Entrance Road (see Flora of Red Butte Wash / Hayfield Area)

The wild canterbury bells, Phacelia minor, in Borrego Palm Canyon, is often misdetermined as desert bluebells, Phacelia campanularia, even though the flowers of P. minor are as purple as it gets and those of P. campanularia are very clearly quite blue except on the outer surface. The root cause seems to be a belief that P. minor is only found on the coastal side of the mountains, and P. campanularia is a desert plant. In fact, that distinction based on location is used in the Munz and Beauchamp keys.

Jane Strong and I surveyed Calphotos pictures of P. campanularia and found that at least 12 out of the 34, ~35%, were misdetermined! The misdetermined photographs largely come from locations in or near Anza-Borrego Desert State Park.

Back in 2004, I analyzed specimens of P. minor from Borrego Palm Canyon, and found that they were inconsistent with a determination of P. campanularia in at least four characteristics: corolla not blue, filament teeth not glabrous, stamens not 20-45 mm, and style not cleft 1/3 to 1/2 its length.

Nonetheless, the question came up again last week after finding that our photographs of P. minor in Borrego Palm Canyon had a bluish tinge. I wondered if the different response of cameras to purple flowers, as well as photographers enhancing the blue color in their pictures, could be responsible for some of the photographs of "blue" flowers of P. minor.

The ultimate problem here is that purple is not actually a real color in the sense that it has a single wavelength of light. There is no purple in the rainbow (don't confuse violet with purple). Instead, purple is what the human eye/brain perceives from a combination of red and blue light. Because cameras, monitors, and printers all respond differently to red and blue light than does the human eye/brain, purple flowers are notoriously hard to reproduce accurately in photographs.

So it was clear that it was time to go see some real P. campanularia and see what they look like to the eye and to the camera. Despite intensive searches for it in Borrego Palm Canyon, I had never found it there.

Elize Van Zandt had previously reported a remarkable bloom on the south side of Joshua Tree National Park near Chiriaco Summit that included P. campanularia among the over 50 species she noted were in bloom there on 20 January 2008. This bloom was quite localized, created by a late-September 2007 thunderstorm that started the plants growing early. So this was a great excuse to get out there and see that bloom, which included a handful of other species I'd never seen before.

Even though this destination is 2.5 hours one-way driving time from my house, I was joined by Wayne Armstrong, Jane Strong, Michael Charters, Dave Stith, Eric Baecht and his friend Pat.

As we drove close to Chiriaco Summit, we were delighted to see increasing numbers of Arizona lupine, Lupinus arizonicus, in good bloom, alongside I-10. When we took the Hayfield Road exit and headed north, we were in a wonderland of flowers! This was so amazing to see, since most parts of the Borrego Desert don't even have native annuals growing at all.

We began recording all the species we saw, and soon came across the first desert bluebell. We were amazed at the size of the flowers, often 40 mm (1.5 inches) and longer, and how clearly different this was than the P. minor in Borrego Palm Canyon. But we were stunned when we looked into the flowers and discovered five white spots! There is no mention of spots in the flowers of P. campanularia in any of the standard southern California floras. Jaeger's Desert Wildflowers is the only reference that mentions the spots.

We kept checking flower after flower, and finding almost every one had spots. We puzzled over what species we were actually seeing until we sat down and keyed it out from scratch. There was no doubt about the determination; only P. campanularia could fit these plants. Yet no flora mentions that the flowers have spots.

At home, I checked online pictures for correctly-determined P. campanularia and found that plenty of the pictures showed spots. The lack of mention of the spots in floras is almost surely due to the rapid fading of the corolla in vouchers. The few corollas I took home had become completely colorless, without evident spots, in only two days.

There is also the factor of you only see what you look for. Jane and I had both looked at the online photographs of P. campanularia the night before the trip, and hadn't noticed the spots that are clearly evident in many of the photographs. Michael Charters had even printed out a large picture of P. campanularia that we had all examined as we were waiting for everyone to show up, and that photograph clearly showed spots!

Back in the field, we continued to find treasure after treasure, including three ghost flowers in bloom. There were six species I had never seen before, including a cactus I had never even heard of before that resembled Mammillaria: spinystar, Escobaria vivipara var. alversonii.

It was hard to turn around, but we decided we wanted to check out the Cottonwood Road and Spring area, so we did.

Cottonwood Road was equally ablaze with wildflowers. We stopped to examine the P. campanularia there; they were exactly the same, large size and spots.

But after we entered the mountains proper, the landscape reverted to the all-too-familiar parched version, with hardly an annual in sight. Cottonwood Spring itself had no water, and there was only a hint of moistness under one of the Palms. Clearly, the late summer rain had missed this area. The severe drought continues in most of the Sonoran Desert in California. Jane relayed a report from a friend who had recently hiked the higher country of Joshua Tree National Park and found not a single wildflower.

At home, we got an answer to our question about how different the color of the two species are in photographs. There is indeed some red in the corolla of P. campanularia, as shown by the following photographs:

The photographs were taken through a filter that primarily transmitted only blue, and another filter that primarily transmitted only red. Since the flowers appear blue through the blue filter, and red through the red filter, the flowers contain both red and blue. If those colors were not present in the flowers, the flowers would appear black through the filters. (You can also see the purple outside of the corolla at the left side of the picture with the blue filter.)

The following picture overlaps the red and blue filter at the left, showing that essentially no light makes it through both filters.

Note the overturned corolla lobe on the flower at the right, showing the purple back of the lobe on top of the blue front of the flower.

I'll photograph the next P. minor flowers I see with the same filters to see how much difference there is.

Wayne's photographs show that if you don't artificially enhance the blue in pictures of P. minor, the two species present different colors, preserving the difference seen by the eye. However, the difference is fairly subtle for some flowers, as can be seen by flipping back and forth between these two flowers from Wayne's page: P. campanularia and P. minor. (Open both flowers up in separate browser pages and flip between them.)


16 February 2008: Whitewater Canyon / Joshua Tree National Park: Red Butte and Carey's Castle Wash (see Flora of Red Butte Wash / Hayfield Area)

Jane Strong and I decided to return to the Red Butte area to explore further, and to work on the identifications of some of the species, especially the cryptanthas. We were delighted that James Dillane and Lara Hartley were able to join us.

We stopped first at Whitewater Canyon in the Banning Pass to look for Phacelia campanularia ssp. campanularia. There had been considerable discussion after the last trip as to what the differences between these subspecies really were.

Jane found the plants immediately, and we were all struck by the considerable difference with the ssp. vasiformis at the Red Butte area. These Whitewater plants were so different we're not sure they should share the same species with the plants at Red Butte Wash! These are tiny plants, with small flowers, growing in masses on rivers of gravel down steep slopes, whereas the plants at Red Butte are much more robust plants, with much larger flowers.

Judging from these two sets of plants, the length of the corolla is the best discriminant of the subspecies by far. The shapes of the flowers are different as well, but they are not described well in the floras. The corollas of these ssp. campanularia are not the bell-shaped stated in the keys, since the bases are quite narrow whereas a bell has a wide base. Drawings of the outline of the corollas show the shape is in fact close to funnelform, the description of ssp. vasiformis! No wonder there has been much discussion of which subspecies had which shape. A much better distinction might be that ssp. vasiformis is actually indeed vase-shaped, as its name implies, with a distinct lengthy tubular portion of the corolla. In contrast, ssp. campanularia has only a very short tubular portion and is shaped more like a small bell with a narrow base.

These plants all had spots in the corolla. So far, every example of this species we've seen, both in the field and in online pictures, has spots, even though the floras don't mention them. Only Jaeger mentions that this species has spots.

We then headed for Red Butte Canyon. Once there, Lara took off in search of the desert twining snapdragon, Antirrhinum filipes, we had seen on the last trip. Jane, James and I began working on the species needing further identification work at the parking area, and then headed to the main wash to the west, Carey's Castle Wash.

It was striking how different the species were on this route than on our route last time. Last time, I had looked hard for a species I had never seen before, desert golden poppy, Eschscholzia glyptosperma, but found only zillions of plants of Parish's poppy, E. parishii. In contrast, the route we took today was dominated by E. glyptosperma, with only a few plants of E. parishii!

In addition, only Carey's Castle Wash had golden sun-cup, Camissonia brevipes; desert pepper-grass, Lepidium fremontii; and smooth western tansy-mustard, Descurainia pinnata ssp. glabra. Only Red Butte Wash had narrow-leaf sun-cup, Camissonia refracta.

I was totally shocked by the Lepidium fremontii; I had no idea any Lepidium was shrubby!

We picked up 21 taxa on our route today, increasing the number of taxa on the checklist from 74 to 95.

One of the highlights was the Hall's purple bush, Tetracoccus hallii. We had seen specimens of this species on the previous trip, but had mistaken them as a Lycium just leafing out since this species looks so different (having alternate leaves) from the T. parryi (whorled leaves) on the coast.

James immediately picked up that this was the probable determination for the first plants of this species that we saw today, but we couldn't be sure without flowers or fruit.

Once James and I entered the canyon above the wash, new species became coming fast and furious. We were running out of time, but we didn't want to turn back. Fortunately, at that time, we came upon a specimen of T. hallii just loaded with fruit, revealing its identity clearly, making it easier to turn around.

We were also able to resolve something we had seen on the previous trip. On that trip, we had been confused by the first Trixis, which appeared to have leaves of two kinds. The plant mostly had fairly typical Trixis leaves, but it also had a few much larger, grayer leaves that looked more like desert tobacco leaves. We hadn't spent much time on that specimen, and later thought there might have been desert tobacco growing within a Trixis.

Today, we encountered another such plant, with both kinds of leaves clearly on the same bush.

We also found a number of albino chias, Salvia columbariae, along one stretch of Carey's Castle Wash, and a single albino desert bluebells, Phacelia campanularia, along Red Butte Wash on the way back.

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Last update: 24 February 2008