Penstemon Hybrids
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Hybrid Penstemons

Left: Showy penstemon (Penstemon spectabilis). Center: Hybrid penstemon (P. centranthifolius x P. spectabilis). Right: Scarlet bugler (P. centranthifolius). The hybrid is listed as P. x parishii in some references. It has entire leaves as in P. centranthifolius, but the flowers are intermediate in color, size and morphology. P. clevelandii has flowers that are similar in color to P. x parishii, but its lower and middle leaves are toothed. It is not surprising that it may be difficult to distinguish P. x parishii from P. clevelandii, since P. clevelandii itself is a stabile diploid hybrid species derived from P. centranthifolius and P. spectabilis. See image of P. clevelandii below.

Hybridization in Penstemen flowers. Left: P. spectabilis. Right: P. centranthifolius. Probably the best "fit" for the hybrid P. x parishii is second from the right. There is an intergradation of flowers from the bright red P. centranthifolius to the purple P. spectabilis with reflexed corolla lobes. Populations containing two distinct species and several intermediate hybrids are called hybrid swarms. This phenomenon occurs in a number of flowering plants, including oaks (Quercus) and prickly pears (Opuntia). It is often difficult to identify a species in populations containing intermediate hybrids, particularly when using a dichotomous key.

Showy penstemon (Penstemon spectabilis var. spectabilis).

Penstemons Along The Laguna Crest

Showy penstemon (Penstemon spectabilis var. spectabilis) on the desert crest of Mountain Laguna. This species has glabrous, glaucous leaves that are serrate and connate-perfoliate. The bright red scarlet bugler (P. centranthifolius) also occurs near the desert edge of the Laguna range. A hybrid between these two species named P. x parishii has been reported from the Laguna Rim Trail by Beauchamp (1986). The desert species P. clevelandii var. clevelandii also occurs along the Laguna Rim trail and Garnet Peak.

Left: Scarlet Bugler (Penstemon centranthifolius). Right: Cleveland penstemon (P. clevelandii var. clevelandii). Some reports of the hybrid P. x parishii on the Laguna Rim trail may be P. clevelandii var. clevelandii or a hybrid of the latter species. P. x parishii is a hybrid between P. centranthifolius and P. spectabilis. It is not surprising that it may be difficult to distinguish P. x parishii from P. clevelandii, since Andrea Wolfe's research on the subgenus Peltanthera indicates that P. clevelandii itself "is a diploid hybrid species derived from P. centranthifolius and P. spectabilis." R.M. Straw (1955) also proposed that P. clevelandii originated from hybridization between P. centranthifolius and P. spectabilis. Penstemon clevelandii is found in habitats different from either putative progenitor and is pollinated by both hummingbirds and solitary bees. Thus, if Straw's hypothesis is correct, this hybrid became isolated through ecological and ethological barriers. The primary evidence for recognition of P. clevelandii as a hybrid species is that it resembles F-1's produced from artificial crosses between P. centranthifolius and P. spectabilis, and it is similar in appearance to P. x parishii, a natural hybrid appearing where P. centranthifolius and P. spectabilis occur sympatrically (Keck 1937; Straw 1955). Penstemon clevelandii and P. x parishii have similar corolla shape and color, leaf margins, and leaf vestiture." Wolfe's DNA research confirmed that Shaw's hypothesis was correct. There are other Penstemon taxa in western North America which are derived from hybridization. [See the following image and hyperlinked references.]

Penstemon davidsonii var. davidsonii at 12,000 feet ((3658 m) on the Dana Plateau of the Sierra Nevada. This subalpine species grows among rocks and boulders of the alpine fell fields and talus slopes. Shannon Datwyler is examining the purported hybrid origin of two subspecific taxa is the subgenus Dasanthera (P. davidsonii var. praeteritus and P. fruticosus var. serratus). Both purported hybrid taxa are from P. davidsonii x P. fruticosus progenitors.

Wolfe & Elisens (1993,1994, 1995) & Wolfe et al. (1998)
See Introductory Page For Shannon Datwyler's Research
See Some Interesting Native and Cultivated Plant Hybrids

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