Phacelia nashiana = P. campanularia2

Photographs of Type Specimens and Fresh Flowers
Historical Treatments


Phacelia nashiana is not distinct from P. campanularia ssp. campanularia. The type specimens for the two taxa are indistinguishable, and detailed measurements of fresh specimens of P. campanularia ssp. campanularia show they fit the floral descriptions of P. nashiana much better than the floral descriptions of P. campanularia ssp. campanularia.

This synonymy was probably not recognized earlier due to three factors:


It is surprising that there is so much confusion over Phacelia campanularia. This species, in its ssp. vasiformis, is a widespread taxon in southern California, growing in nearly the entire desert area. It is also widely planted in southern California gardens, since it is often included in wildflower mixes due to its beautiful large flowers and its performance reliability.

Yet if my experience is typical, not many botanists actually see P. campanularia. Despite botanizing in the field over 600 times in literally hundreds of locations over seven years, I only saw this species in one location, Borrego Palm Canyon, in only one year, 2005, until I actively went in search of it in February 2008. Furthermore, the plants in Borrego Palm Canyon clearly fit only the floral descriptions of P. nashiana, not P. campanularia, so until I went in search of P. campanularia, I thought I had never seen P. campanularia at all.

The first source of confusion is between P. campanularia and P. minor. Professional botanical floras, beginning with the 1943 Jepson Flora of California have inadvertently promoted considerable confusion in distinguishing these species. This is most frequently due to reader misunderstanding of exactly what is meant by the word desert, since many botanists, especially amateurs, primarily use location information to distinguish closely-related taxa.

For example, the Munz / Beauchamp key is:

48. The corolla purple, slightly constricted at throat. Cismontane. ...P. minor
48'. The corolla deep blue, not constricted at throat. Deserts.... P. campanularia

The word deserts here, as also used in the Jepson Desert Manual, does not include the very western edge of the deserts, such as Borrego Palm Canyon, which have a number of cismontane taxa that spill over the mountains to there. In fact, Munz and Beauchamp both explicitly state that P. minor occurs at the edge of the desert, with Beauchamp quoting Borrego Palm Canyon as a locality.

There are two additional problems in separating the species using this key. Specimens of P. minor often do not exhibit a throat constriction at the edge of the desert. Also, cameras do not record purple in the same way as seen by the human eye. Purple flowers often come out bluish in pictures, especially if the photographer expects to see blue flowers and tweaks the colors in the photos to enhance the blue.

The following picture shows P. minor photographed side by side with P. campanularia, using fluorescent lighting at home at night, on top of the purple picture of P. parryi from Margaret Filius' Native Plants Torrey Pines State Reserve and nearby San Diego County Locations:

The pictures of the flowers above all came from the same photograph, processed in exactly the same way, but were cut and pasted to place them directly together (see original photograph). If you have a copy of Filius' book, you can compare the photograph to the excellent rendition of purple in the book on p. 123.

The color of my photograph of Filius' picture, displayed on my monitor, matches the color of the printed photograph well. To my eye, the color of my P. minor sample (the real sample, not my photograph) was identical to the color of Filius' printed picture, but you can see there is a distinct bluish tone in the picture above that was not apparent to my eye. However, the color of the photograph of P. minor still is markedly different from the deep blue of P. campanularia.

The lack of experience in seeing P. campanularia, as well as such floral keys, probably account for the widespread misidentification of desert specimens of P. minor as P. campanularia. Over one third of the photographs (12-13 out of 34) of "P. campanularia" at Calphotos are actually clearly photographs of P. minor. The binder at the Anza-Borrego Desert State Park Visitor Center showing labeled photographs of wildflowers has this same error. James Lightner, widely-traveled in San Diego County, with over 1,000 species described and photographed in his San Diego County Native Plants book, never found P. campanularia, and was clearly troubled by this situation, stating desert plants [are] said to have bluer (less purple) flowers.

The confusion over the color difference and geographic location is promoted by the common name of California bluebells for P. minor and Desert bluebells for P. campanularia. In fact, as late as 1923, professional floras were confused about the color difference. Davidson, in his 1923 Flora of southern California, says the corolla of P. campanularia is purplish or blue. He even gives a location of P. campanularia in Rubio Canyon on the coastal slopes of the San Gabriel Mountains well within P. minor territory. The difference in color was correctly picked up by Jepson in his 1925 Manual of the Flowering Plants of California, and subsequent floras followed that lead.

The second source of confusion is with the subspecies of P. campanularia. Botanists in the true desert away from the montane borders, are quite familiar with P. campanularia ssp. vasiformis since it is widespread in the true desert. However, many aren't sure which subspecies of P. campanularia they are actually seeing there and wonder whether the subspecies actually exist.

The problem in distinguishing the two subspecies of P. campanularia is due to two sources. First, ssp. campanularia is uncommon, found only in a very narrow strip along the western edges of the desert. Even where it is present, it is often uncommon. For example, although there are three vouchers of it from Deep Canyon, it does not appear in the Flora of Deep Canyon by Zabriskie.

Hence this subspecies is not seen by most desert botanists who then have to rely on descriptions of these taxa in the floras. Due to variability among the plants on a single taxon, we botanists have an uncanny ability to try to make two taxa out of one when we have only seen one taxon; I've done this many times. Second, the floras have incorrect descriptions of ssp. campanularia, and the words used to describe the shape of the flower are easily subject to misinterpretation. See below for details on both of these problems.

The analysis reported in this paper came about when I was stimulated to go look for P. campanularia after specimens of P. minor in Borrego Palm Canyon were once again misidentified as P. campanularia by yet another excellent botanist. My goal was to photograph the two species side by side so that people could easily see the differences between these two taxa.

After seeing specimens of P. campanularia ssp. vasiformis in Joshua Tree National Park on 11 February 2008, there was then considerable discussion as to which subspecies those specimens actually were. The discussion centered almost entirely on how the observed shape corresponded to the words used in the Jepson Manual to describe the shape of the corolla for the subspecies. Hence I was stimulated to go look for ssp. campanularia on 16 February 2008 at Whitewater in Banning Pass just north of Palm Springs, in order to document the differences between the two taxa.

The plants of ssp. campanularia at Whitewater were so different from the plants of ssp. vasiformis at Joshua Tree National Park that I wasn't even sure they should share the same species name. It was no wonder that Jepson defined P. nashiana as a new species in 1943 if he was comparing it only to P. campanularia ssp. vasiformis! These Whitewater plants were tiny, with tiny flowers lacking any noticeable tube at all, growing in masses on rivers of gravel tumbling down steep slopes. In contrast, the Joshua Tree National Park plants were large plants, with large flowers with a very lengthy tube, growing individually in flat washes.

Satisfied with the marked difference between the two subspecies found in those trips, as well as with the difference between the plants at Whitewater and the specimens of P. nashiana I had found in 2005 at Borrego Palm Canyon, I planned no further work on these taxa.

But on 2 March 2008, in the course of other work, I spent ten minutes searching for specimens of P. campanularia ssp. campanularia vouchered from the mouth of Deep Canyon, and found them. Analysis of those samples quickly revealed they bridged the gap between the Whitewater specimens determined as P. campanularia ssp. campanularia and the Borrego Palm Canyon specimen determined as P. nashiana, which led to the results presented in this page.

Photographs of Type Specimens and Fresh Flowers

The Botanical Type Specimen Register of the Department of Botany of the Smithsonian National Museum of Natural History contains excellent images, with good resolution and scale, of isotype specimens for both subspecies of P. campanularia, as well as of P. nashiana. The flowers from those images are reproduced below for comparison.

Note that every picture from all of the isotype specimens in the table below is to the same scale. All pictures in the following table are copyright © Smithsonian Institution, Department of Botany.

P. nashiana
© Smithsonian Institution
Corolla 20 mm

© Smithsonian Institution
Corolla 17 mm

© Smithsonian Institution
Corolla 16 mm

© Smithsonian Institution
P. campanularia ssp. campanularia
© Smithsonian Institution
Corolla 19 mm

© Smithsonian Institution
Corolla 19 mm

© Smithsonian Institution
Corolla 16 mm

© Smithsonian Institution
Corolla 22, 20 mm
P. campanularia ssp. vasiformis
© Smithsonian Institution
Corolla 29 mm

© Smithsonian Institution
Corolla 34, 37 mm

© Smithsonian Institution
Corolla 28 mm

© Smithsonian Institution

Fresh flowers, from the images at CalPhotos and from my own pictures, are shown below. Note that these pictures are not to scale; only two pictures have a ruler or finger in it for scale.

P. nashiana
© 2003 Heath McAllister
North of Freeman Junction in the Owens Peak Wilderness. (Kern County)

© 2006 Aaron Schusteff
Red Rock State Park (Kern County)

J. E.(Jed) and Bonnie McClellan © California Academy of Sciences
Sand Creek Canyon (Kern County)
P. campanularia ssp. campanularia
Tom Chester
Deep Canyon
Santa Rosa Mountains

Tom Chester, Whitewater, north of Palm Springs

Tom Chester, Whitewater, north of Palm Springs
P. campanularia ssp. vasiformis
Tom Chester, Red Butte Wash, Joshua Tree National Park

Tom Chester, Red Butte Wash, Joshua Tree National Park

Tom Chester, Red Butte Wash, Joshua Tree National Park

Historical Treatments

P. campanularia had no subspecies defined until 1955. Thus at the time Jepson defined P. nashiana in 1943, he only distinguished it against the entire range of parameters for the entire species of P. campanularia, which is dominated by plants of ssp. vasiformis.

Jepson defined P. nashiana in his Flora of California: Volume 3, Part 2 with the following key:

Corolla subrotatish to turbinate-campanulate, cleft about to middle
     Corolla deep-violet, purple or blue, 3/4 to 1 1/4 inches broad, the tube with 5 large whitish spots; ovules about 12 to 30 to each placenta
          Stem (main axis proper) stout and short (1 to 3 inches long, densely leafy, bearing flowering branches 3 to 5 inches long; se Inyo Co. .... P. nashiana

Corolla oblong-campanulate, shallowly cleft
     Corolla funnelform-campanulate, that is, much broader at throat than below; ovules 20 to 30 to each placenta; transmontane deserts ...P. campanularia

A rotate corolla is a flat, disc-shaped corolla, with little or no tube. Turbinate means top-shaped. Campanulate means bell-shaped, usually with a broad base. Turbinate-campanulate means bell-shaped with the narrow base of a top. Oblong means having parallel sides, usually two to four times longer than wide.

As can be seen from the above pictures of the type specimens, both P. nashiana and P. campanularia ssp. campanularia have identically-shaped corollas which are indeed subrotatish to turbinate-campanulate. They definitely are not oblong in any way, nor do they have any discernable cylindric tube. The corollas of both taxa are cleft about to middle (at the base of the lobes), and hence both would clearly key to P. nashiana in Jepson's key.


It is clear from Jepson's description of P. campanularia that he is only describing ssp. vasiformis: corolla funnelform-campanulate (the tube widened upward, not at all ventricose), 3/4 to 1 1/2 inches long (19 to 38 mm).

The word funnelform is what confused us at Joshua Tree National Park. Our current mental images of a funnel are actually top-shaped, due to funnels used for oil changes and kitchen use. However, in botanical terminology, funnelform is applied to anything that widens upward, as in the corolla tube of ssp. vasiformis pictured above, and as explicitly stated in Jepson's description.

Jepson gives the corolla length for P. nashiana as being 6-9 lines long (13-19 mm), which is consistent with the P. nashiana type specimen corolla length of 16-20 mm, which itself is indistinguishable from the P. campanularia ssp. campanularia type specimen corolla length of 16-22 mm.

Jepson's key and description of P. nashiana fits the type specimen of P. campanularia ssp. campanularia perfectly, and provides no way to distinguish P. nashiana as a separate taxon. Jepson was probably simply not aware of the population of P. campanularia, later separated out as ssp. campanularia, that is identical to his P. nashiana, since it is a relatively rare taxon.

By the way, Jepson oddly describes the corolla of P. nashiana as being violet, not blue.

Twelve years later, G.W. Gillett defined P. campanularia ssp. vasiformis in Univ. Calif. Publ. Bot. 28: 64, 1955, recognizing for the first time that the relatively uncommon plants of ssp. campanularia were distinct from the majority of the plants of P. campanularia. (The specimens called P. nashiana and the other specimens called P. campanularia ssp. campanularia also share the trait that they are uncommon taxa.)

Munz, in both his 1959 California Flora and 1974 Flora of Southern California, continued using the Jepson key to separate them, adding that the corollas of P. campanularia had a tube twice as long as the limb:

45. Corolla open-campanulate, the tube ca. as long as the limb
     46'. Fls. Deep blue. W. Mojave Desert ...P. nashiana

45'. Corolla tubular-campanulate or campanulate-funnelform, the tube ca. twice as long as the limb.
     48'. The corolla deep blue, not constricted at the throat. Deserts....P. campanularia

Once again, plants of P. campanularia ssp. campanularia key directly to P. nashiana, and only ssp. vasiformis keys to P. campanularia.

Wilken, Halse and Patterson, in the 1993 Jepson Manual, gave a much more detailed key to separate the taxa:

32. Calyx lobes 3-4 mm, 5-8 mm in fr; stamens 12-20 mm; corolla 10-18 mm, tube white, limb blue, throat with white spots below sinuses; style 10-20 mm ...P. nashiana

32'. Calyx lobes 6-8 mm, 9-11 mm in fr; stamens 20-45 mm; corolla 15-40 mm, bright blue; style 20-45 mm ...P. campanularia
     33. Corolla ± bell-shaped, 15-30 mm; petiole 1-10 cm ...ssp. campanularia

The specimens of P. campanularia ssp. campanularia from Whitewater, Deep Canyon, and Borrego Palm Canyon are analyzed against that key in the next section.


On 16 February 2008, I sampled and vouchered seven flowers, from five or six different plants, from the population of P. campanularia ssp. campanularia just east of the bridge over the Whitewater River of the Whitewater Cutoff Road. I measured nine characteristics for each flower, with the results shown in the table below. Photographs of two flowers from Whitewater are shown above.

On 2 March 2008, I sampled and vouchered seven flowers, from three or four different plants, from the population of P. campanularia ssp. campanularia at the mouth of Deep Canyon, immediately west of the Boyd Research Station of U.C. Riverside. I measured the same nine characteristics, reported in the table below. A photograph of one flower from Deep Canyon is shown above.

On 1 March 2005, I vouchered specimens of P. nashiana from Borrego Palm Canyon, and measured a number of flowers for five characteristics, reported in the table below.

All measurements in the following table are in mm, and are lengths unless stated otherwise. For comparison, the values given in the Jepson Manual key are given in the last two lines of the table.

SampleCalyxCalyx LobeMax Calyx Lobe WidthCorollaCorolla Width At Tips of LobesStyleStyle LobesMin. FilamentMax. Filament
Deep Canyon5.5-8(13.2)5-7.6(12.5)1.2-1.911-1617-2210.5-184.6-119.5-16.512-17
Borrego Palm Canyon 7-7.5 9-14 848-10
All samples5.5-10(13.2)5-9(12.5)1.2-1.99-2317-268-19.54-118-21.5
P. nashiana 3-4 10-18 10-20 12-20
P. campanularia ssp. campanularia 6-8 15-30 20-45 20-45

There is a progression to smaller corolla length from Whitewater in the north to Borrego Palm Canyon in the south, but more extensive sampling is required to say whether that is significant or not.

How do these specimens from Whitewater, Deep Canyon, and Borrego Palm Canyon compare against the characteristics for the two taxa under the assumption that these two taxa are actually distinct?

First, it is easy to see why the Borrego Palm Canyon specimens were determined as P. nashiana. The minimum lengths for its corolla, style and filaments are even shorter than the minimum lengths for P. nashiana. The maximum value for the lengths of the style and filaments of Borrego Palm Canyon plants does not even come close to the minimum values for P. campanularia. The corollas of the Borrego Palm Canyon plants have the white spots, which are given in the key only for P. nashiana. If any set of plants were ever going to be determined as P. nashiana, the Borrego Palm Canyon plants would be that set.

The only discrepancy of the Borrego Palm Canyon specimens with the key and description of P. nashiana is the length of the calyx lobes in flower. In my experience, underestimating the maximum calyx lobe length in flower is a general problem for the description of Phacelia species in all floras. I suspect this is because phacelias require fruit to be properly keyed out, and that the calyx length decreases in the later flowers after the first ones have gone to fruit. I have found similar errors in the calyx length for Plagiobothrys undulatus.

For example, I measured calyx lobes of 10 to 11 mm for five randomly-selected P. minor flowers from Fallbrook in north San Diego County on 2 March 2008, yet the values given in the Jepson Manual are only 5-6 mm. These were among the first flowers produced by these plants. (The flowers were actually picked in the dark, by flashlight, and hence no visual selection for the largest flowers occurred.) Also, the type specimen for P. nashiana has calyx lobes of ~7 mm for one flower (the flower pictured on the right in the first set of pictures above), far beyond the range of 3-4 mm given in the Jepson Manual for that species.

Hence I will ignore the calyx lobes in comparisons to values given in floras.

To determine the plants from Whitewater and Deep Canyon, I first did a principal components analysis (PCA) using my measurements and the values for every measured characteristic as reported in the floras for each taxon. The PCA results, shown below, clearly demonstrate that:

However, if these plants are all determined as P. nashiana, P. nashiana must be synonymous with P. campanularia ssp. campanularia, since Whitewater is the home of P. campanularia ssp. campanularia, with more specimens vouchered from that location than from anywhere else.

Thus P. nashiana is not actually distinct from P. campanularia ssp. campanularia, and the Jepson Manual and other floras are not reporting the actual range for these characteristics of P. campanularia ssp. campanularia. This supports the visual conclusion from examination of the type specimens for each taxon, and the clear evidence that Jepson was not aware of the characteristics of P. campanularia ssp. campanularia when he defined P. nashiana.

Before showing the PCA results, it is easy to see how the PCA gave that conclusion from direct examination of some of the measured characteristics against the Jepson Manual key.

The style and filament lengths give the cleanest discrimination: they are only consistent with a determination of P. nashiana for the Whitewater, Deep Canyon, and Borrego Palm Canyon samples. The ranges for both characteristics (style: 8-19.5 mm; filaments: 8-21.5 mm) are almost exactly the ranges given for P. nashiana (style: 10-20 mm; filaments: 12-20 mm), which are completely different for the ranges given for P. campanularia ssp. campanularia (style: 20-45 mm; filaments: 20-45 mm).

The plot below visually shows the results in the table above. It also includes measured specimens of P. minor from Fallbrook, North San Diego County, and specimens of P. campanularia ssp. vasiformis from Red Butte Wash, Joshua Tree National Park.

Note that the individual flowers for the Whitewater, Deep Canyon and Borrego Palm Canyon specimens fall almost precisely along the line for P. nashiana, covering the full range of that line. The Borrego Palm Canyon point is the most extreme point of all of those specimens, showing why it had to be determined as P. nashiana.

The points for P. campanularia ssp. vasiformis fall along the line for that taxon reasonably well, with the points for P. minor falling along the lower portion of its line.

The next plot shows visually that P. nashiana is the best fit for the corolla length as well:

Clearly, the determination of the Whitewater, Deep Canyon, and Borrego Palm Canyon specimens is only consistent with P. nashiana. There are only three samples of the 15 that exceed the maximum corolla length given in the floras for P. nashiana. It would take only a slight extension of the corolla length range for P. nashiana to make all these plants consistent with that taxon.

The full PCA leads to the same conclusion, whether or not the calyx lengths are included. The following plots show the results using just the corolla length, style length, style lobe length, and filament length:

Note that the lines for the taxa result from using the parameters in the floras, which don't include the variability found within each taxa from flower to flower. Furthermore, there is no guarantee that the lines are "centered" on the points from individual flowers, since the extreme values for each characteristic have large scatters. The proper way to do this PCA is to measure a number of flowers of P. nashiana from near its type locality, which I'll try to do in the future. But the values in the floras are good stand-ins for those taxa, as long as one knows not to expect each species to exactly follow its corresponding line.

If one had to pick a taxon for the Whitewater, Deep Canyon, and Borrego Palm Canyon specimens, it would have to be P. nashiana from the above plots. In both plots, the closest line to those points is the line for P. nashiana, and the points follow the slope of that line best.

As mentioned above, the only reasonable conclusion from this analysis is that P. nashiana is not distinct from P. campanularia ssp. campanularia.


The following maps show the distribution of vouchers for P. campanularia ssp. campanularia, including P. nashiana as a synonym, and for P. campanularia ssp. vasiformis:

Distribution of vouchers of P. campanularia ssp. campanularia, including P. nashiana

Distribution of vouchers of P. campanularia ssp. vasiformis

You can flip between the two maps by opening each mag in a separate browser page, and then using alt-tab or the equivalent to alternately display each map.

The two taxa largely have different geographic ranges, with ssp. campanularia occurring in the wetter areas next to the mountains, and ssp. vasiformis occurring in the deserts proper.

Because the rainfall gradients are very steep on the desert side of the mountains, the distributions appear to overlap there, but they actually separate well. The following map is a blow-up of this transition area, showing the separation better:

Detail Map Showing Distribution of vouchers of P. campanularia ssp. campanularia and ssp. vasiformis

There are only four vouchers of one subspecies within the range of another. The primary exceptions are the three vouchers of ssp. campanularia just west of Needles. Those specimens should be reexamined to make sure of their determination. There is just a single voucher of ssp. vasiformis that appears to be within the range of ssp. campanularia, which could in fact be correctly determined. It should be checked as well.

There is nothing unusual about the geographic distribution of P. campanularia ssp. campanularia, including P. nashiana. Many taxa are disjunct between the Sierra Nevada and the San Bernardino Mountains.


I thank the Smithsonian National Museum of Natural History for making available images of the isotype specimens of these species online, and Anne Kelly and the Boyd Deep Canyon Research Center for access to Deep Canyon. Voucher data provided by the participants of the Consortium of California Herbaria ( I thank Michael Charters and Jane Strong for comments on the manuscript.

Go to:

Copyright © 2008 by Tom Chester
Permission is freely granted to reproduce any or all of this page as long as credit is given to me at this source:
Comments and feedback: Tom Chester
Last update: 5 March 2008