Plant Species of San Jacinto Mountains: Allophyllum species

A. divaricatum
A. gilioides ssp. violaceum
A. glutinosum
Fig. 1. Left: Allophyllum divaricatum. Middle: A. gilioides ssp. violaceum. Right: A. glutinosum.

It is easy to distinguish these species by their flowers. A. divaricatum has pink to pink-purple corolla lobes, and a red-purple corolla tube. The corolla of A. gilioides ssp. violaceum is deep blue-purple color throughout. A. glutinosum has most of its flowers with long-exserted curved stamens.

Click on the pictures for larger versions.

We have three Allophyllum species in the San Jacinto Mountains: A. divaricatum, A. gilioides ssp. violaceum, and A. glutinosum. These three species are easy to tell apart from a fresh flower (see Fig. 1), if you know what to look for. Despite that, there has been confusion in the past between all three of these species. Difficulties include mistaking the red-purple (on the outside) flower of A. divaricatum with the blue-violet flower of A. gilioides ssp. violaceum, and finding flowers of A. glutinosum that are not fully mature and thus don't have long-exserted curved stamens. Vouchers (pressed, dried specimens) appear to be even more problematic since the flowers may have closed and shrunk, and changed their colors as they dried. Vouchers have an additional problem, since ALL the Allophyllum specimens were called subspecies of A. gilioides until 1955. Hence vouchers determined only as A. gilioides, whose last determination was made before 1955, and in many cases for some time afterwards, are ambiguous as to what the actual determination would be now.

A. divaricatum is our most common species by far, yet it was not considered to be in the flora of the San Jacinto Mountains, or anyplace else south of the Transverse Range, until Riefner and Boyd published a short "Noteworthy Collections" article in Madrono in 2007! Prior to that time, collections of A. divaricatum had been misdetermined as A. gilioides ssp. violaceum or A. glutinosum.

For many years, all we found was A. divaricatum in our surveys. When we finally found some plants of A. gilioides ssp. violaceum in Round Valley, we were ecstatic! Fig. 2 show photographs of plants of both species that were growing in populations just a few hundred feet apart, in different habitats. The differences between them are labeled, and are precisely as given in the keys to separate these species.

Fig. 2. Labeled photograph showing differences between plants of A. divaricatum and A. gilioides ssp. violaceum. Click on the photo for a slightly larger version.

Fig. 3 shows flowers of both species photographed together, with the same lighting conditions, from a sample of each population collected for vouchers.

Fig. 3. The leftmost flower is A. gilioides ssp. violaceum; the rightmost flower is Allophyllum divaricatum. The flowers were photographed together in the field, so the lightning conditions are the same for both flowers.

Click on the pictures for larger versions.

A. glutinosum is primarily a fire-follower at lower elevations, so we began to see it in abundance only after the 2013 Mountain Fire.

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Updated 21 December 2020.