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Phacelia glandulosa

Phacelia glandulosa

Phacelia glandulosa

Phacelia glandulosa

Phacelia bakeri (Baker's Phacelia)
Boraginaceae (Forget-Me-Not Family)

Subalpine, alpine.  Rocky openings, talus.  Summer.
Colorado Trail near Stony Pass, July 21, 2011 and July 22, 2012.

This exotic, highly glandular Phacelia is amazingly intricate and ornate with long, exserted filaments and styles and a myriad of glandular hairs. P. bakeri is found from mid-montane elevations to wind-swept tundra.

P. bakeri is quite similar to Phacelia glandulosa. Click to see P. glandulosa. The first characteristic to observe in separating the two species is the vegetation zone. Almost all collections of P. bakeri in Colorado are from the subalpine and alpine zones, although there are some collections from as low as 7,000 feet. Flora of the Four Corners Region shows the range as 7,000-12,200'.

P. glandulosa, on the other hand, apparently is only found in the foothills and montane and, in fact, in some of its range it is found in the semi-desert environment. (A variety in southwest Wyoming is actually named P. glandulosa var. deserta.) A Utah Flora gives the Utah range for P. glandulosa as 4,800-6,300'.

From my inspection of various floras and on-line herbaria records, I have found that in Colorado P. bakeri and P. glandulosa share elevational levels between perhaps 6,500-9,500, but above that you are fairly safe in assuming your plant is P. bakeri and below 6,500 it is P. glandulosa.

Following are several attempts at separating Phacelia bakeri from Phacelia glandulosa. If the distinguishing characteristics seem inconsequential, confusing, and contradictory to you, then you are in the very good company of the great botanists John Torrey (see last paragraph in this box) and H. D. Harrington, author of the 1964 Manual of the Plants of Colorado, who states that "the suggested differences between Phacelia glandulosa and P. bakeri will not work out for our plants".

Understanding several terms is key to understanding the following discussion:
1) "Excavations":  Deep gouges. Instead of using "excavations" I think "troughs" or "gullies" or "deep indentations" or "gouges" should have been used. The point is that the seed surface has one or two deep gouges running the length (or sometimes the breadth) of the seed.

2) "Raphe": A steep ridge on the seed surface. The raphe is the remnant of the seed stalk.

It appears that all recent keys are based on the work of Duane Atwood, the recognized expert on Phacelia. Atwood states the following in his 1975 revision of the Phacelia genus:

"Size, shape, and surface markings are diagnostically important [for the Phacelia genus]. The seeds [of Phacelia] are unique in having the ventral surface excavated [gouged] on one or both sides of a prominent ridge." However, Atwood indicates that the ventral surface of Phacelia bakeri is unique among Phacelia in having no excavations. Instead, "On the ventral surface the raphe is elevated above the normally excavated portions, thus giving the seed a triangular shape in cross-section." Also, the seeds of P. bakeri have no excavation on the dorsal side. Instead, "The dorsal surface [is] flat with only a faint longitudinal groove down the center".

In sum, Atwood indicates that P. bakeri differs from P. glandulosa "in the lack of excavations on the ventral surface of the seeds, usually greener herbage, later flowering time, and distribution [i.e., elevation]". Atwood indicates that P. bakeri is found from the lower montane to the alpine whereas P. glandulosa is found from the semi-desert to the lower montane.

In his Colorado Flora, William Weber agrees with Atwood's assessment of the excavations but gives a different (or at least unclear) elevational zone:
13a. Seeds not excavated ventrally. Sagebrush valleys. P. bakeri.

13b. Seeds excavated ventrally. Steep shale-clay slopes. P. glandulosa.

Range map © John Kartesz,
Floristic Synthesis of North America

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Species present in state and native
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Species present and not rare
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Phacelia bakeri

Range map for Phacelia bakeri

Range map for Phacelia glandulosa