Penstemon eatoni - the Eaton Firecracker or Firecracker Penstemon

Submitted by Mark McD on Thu, 07/08/2010 - 10:41

Sometimes Penstemon barbatus and Penstemon eatoni get confused, both being tall scarlet-flowered penstemons. I don't currently have a good photograph of Penstemon barbatus, but I'm showing a couple photos of Penstemon eatonii taken in my garden in 2009. These photos are slightly out of focus, sorry about that, but at least they depict the downcurved-arched disposition of the flowers on Penstemon eatonii, as opposed to the straight "shark-tubes" of P. barbatus. If any forumists have a good photo of P. barbatus, in any of its color forms, please post them here.

USDA Information page:

Lots of excellent detailed photos on the CalPhotos site:

This gorgeous photo clearly shows the downcurved arch shape of the flowers on the Eaton Firecracker:


Submitted by Kelaidis on Thu, 07/08/2010 - 11:15

Something about your plant doesn't look quite right: for one thing, Penstemon eatonii usually blooms in spring: this .jpg was taken early last May near Moab: you can see it was in full bloom two months ago.

There are numerous red penstemons actually. P. barbatus is immediately diagnostic because of the reflexed lower petals.

I think your's is more apt to be Penstemon centranthifolius, which also has tubular flowers and a somewhat different habit. Bobbie! Where are you?

Submitted by Mark McD on Thu, 07/08/2010 - 13:31

I love a good mystery ;D  Just spent the last two hours combing through web sites, floras, and the Lodewick Penstemon Field Identifiers.  I'm still leaning towards P.eatonii on my plant, although certainly P. centhranthifolius is VERY close to it. Finally found a photo I took in May this year, so uploaded this clearer photo here.

Regarding flower time, it seems that it is quite variable, depending on where it is found in its relatively vast range through much of Western USA.  Many of the USDA and CalPhotos images have detail info giving the date the photos are taken, and they seem to run the gamut.  Mine flowered in May, just found a photo missed in my first search for an image, taken in May 2010. 

The other thing to consider in this sleuthing, P. eatonii has 3 subspecies described, found in 8 Western USA states, thus probably displaying great variability.  Penstemon centhanthifolius is endemic to California.
USDA plant information on P. centranthifolius:
County-based distribution of P. centranthifolius in California:

Judging from the anther shapes depicted in the Penstemon Field Identifiers, the split anthers more closely resemble P. eatonii than centranthifolius.  I plucked the dried remains of a single flower off an aberrant partial reflowering (top of the stem with seed pods elongated and sputtered forth a few more flowers, finishing up around July 4th), then scanned it.  One can see the split anther.... whether the shape changes in drying while not in a controlled environment, I don't know... it's just another clue.

More links
Penstemon eatonii -Sotheastern Arizona Wildflowers

Las Pilitas nursery - clickable images of P. centranthifolius

CalPhotos on P. centranthifolius
*Note*- it is possible that some photos on the CalPhotos site are misidentified; with the genus Allium I know this to be true.  One characteristic of P. centranthifolius is that the flowers are on "open racemes", that is, they can face any direction, whereas in P. eatonii they are "secund" or mostly facing the same direction jn each raceme.  Some of the photos here of P. centranthifolius show flowers all around the stem.

There is something about the visual "feel of the plant" that speaks P. eatonii to me versus P. centranthifolius, but I'll keep an open mind, and will scrutinize the fresh flowers next year.

PS: my source is NARGS Seedex 2005

Submitted by penstemon on Thu, 07/08/2010 - 13:42

The red flowered plants are Penstemon eatonii, which has green leaves. The pinkish one is P. barbatus. The "sharkshead" flower with recurved lower lobes is diagnostic. (The are some others that fit this description but the existence of them in horticulture is unlikely)
P. centranthifolius has glaucous leaves and red flowers with no lobes (no place for anything to land on).

Submitted by Mark McD on Thu, 07/08/2010 - 14:03

Thanks Bob.  Forgot to mention checking out both species in your book too (Penstemons,, and the color plate of P. eatonii shows a very nice plant indeed, perhaps with better looking foliage than in mine. What I find distinctive about this species, is how the flowers are so downfacing *and* arching in their downward projection... clearly seen in Plate 24 in your book.

Here's a photo of the cauline foliage.

Submitted by Mark McD on Fri, 07/09/2010 - 06:28

Kelaidis wrote:

Okay: if Bob says it's eatonii, I defer...

Below is a picture of the strange swarm of Penstemon barbatus in full bloom as we speak in Sacred Earth, the Ethnobotanical garden at Denver Botanic Gardens...

Nifty, no?

Panayoti, not having seen the species in the wild, and only familiar with it in cultivation, what characteristics about the "strange swarm" make it strange?  Looks like some light colored forms there.  When I was doing my armchair botanizing yesterday, I came across Penstemon barbatus 'Schooley's Coral'... looks like a nice color selection.

Submitted by penstemon on Fri, 07/09/2010 - 07:47

"Schooley's Coral" is nice, though not entirely willing to come back in spectacular fashion after one winter (just like 'Schooley's Yellow'). This year I planted "Coral Baby" which is a beauty.
The cauline leaves on barbatus are linear; the upper ones are about 2mm across.
I just woke up, but it strikes my not-totally-caffeinated mind that the hybrids of Penstemon barbatus are much less reliable as garden plants than the species pur sang. Regular barbatus seeds around here and flowers as though it were a weed.
Part of this may be the nght-and-day difference between a plant grown in a pot and a plant growing as nature intended, from seed. Not that there's anything wrong with potted plants, but they do start out in an unnatural condition, with a "root ball", something never found in nature.

Submitted by Lori S. on Fri, 07/09/2010 - 11:31

I have a minor anomaly in my yard - P. barbatus hybrids (or so I assume them to be, given the shark's mouth flower shape) in all shades of pink through purple, seed around with abandon (which I find delightful!)  I've yet to find a seedling of the species, however!

Submitted by penstemon on Fri, 07/09/2010 - 19:49

I think that if barbatus shows up as a color other than red, it's most likely to have originated from a commercial selection, like 'Rondo', which might have 'Flathead Lake' as an ancestor. Penstemons rarely hybridize with each other, and I believe never in the garden, though lots of claims to the contrary have been made recently. Plants reported as garden hybrids most likely started out as a seed strain with the potential of displaying characteristics that appear to be the result of garden hybridization.
Barbatus does have color variation in the wild, from red to sort of red to yellow to white; 'Schooley's Yellow' is a stabilized hybrid, I think, between several yellow-flowered forms.
P. eatonii hybridizes with P. centranthifolius in California. (One specimen has been documented.)
The only really documented case of large-scale hybridization is in Section Erianthera (Dasanthera) in the Sierra Nevada and Cascades.

Submitted by Lori S. on Sat, 07/10/2010 - 14:34

Yes, that's absolutely right (... which is stating the painfully obvious, given that it's Bob Nold commenting on penstemons here!  :D)  I had 'Prairie Dusk' and possibly another hybrid of that type long ago, and the pink-to-purple, sharkshead types that seed around here must be the descendants.

Submitted by penstemon on Mon, 07/12/2010 - 22:24

Well, I wouldn't go that far. I just have a lot of documentation here.
If garden hybrids were really as common as sometimes claimed, then they should be as common in the wild. But they aren't. Wilson and Valenzuela (Three naturally occurring Penstemon hybrids, Western North American Naturalist, 62 (1), 2002) found "only a few individuals of each type of hybrid among hundreds of parental individuals" [italics mine].
It doesn't make sense to suggest that a few plants in a garden could produce hybrids, unless those plants themselves were hybrids, say members of a seed strain, which a lot of penstemons in the trade are, ultimately tracing their ancestry to 'Flathead Lake' or something similar.
The difference in anther dehiscence, timing, etc., would make the existence of garden hybrids from true species highly unlikely.

Submitted by Mark McD on Tue, 07/13/2010 - 21:35

That's so COOL Rick!  I do believe that sometimes it is a matter of bringing things together, things that wouldn't necessarily have the opportunity to be together in the wild, but in garden settings, they can start intermingling in ways that defy common belief.  I have many examples with Allium where the native American A. cernuum and A. stellatum will interbreed with European and Asian species, creating all sorts of interesting "new plants".

Submitted by penstemon on Wed, 07/14/2010 - 08:06

Weiser wrote:

So the bottom line for me as a gardener would be, that seed collected in a garden from a known species is most likely to be the real thing. That hybrid offspring are rare.
Did I get that correctly?

Not precisely. There are plenty of plants labeled as true species in the trade that are the real thing.
When plants are introduced into the garden that have, as their ancestor, a hybrid that may have been originally sold as a species, then the possibility for producing a lot of plants that could be described as "garden hybrids" is considerable.
Hybrid offspring in the wild are rare, according to the documents I have. Penstemon species are often sympatric and show no evidence of crossing. Penstemon glaber var. alpinus, P. confertus, and P.whippleanus grow right next to each other on the road to the rock garden on Mt. Goliath, but no hybrids are evident.
If penstemon hybrids are rare in the wild, but apparently common in gardens, that leads me to my next question .....

Submitted by penstemon on Wed, 07/14/2010 - 19:14

The next question being, and it's a rhetorical one, if penstemons don'y hybridize in the wild much, but do a lot in the garden, then the obvious conclusion is that the plants are happier in the garden.
The question....and this may be a, if plants are happier in the garden, what advantage is there to knowing what the plant's native habitat conditions may be?

Submitted by Mark McD on Thu, 07/29/2010 - 20:49

Nold wrote:

The next question being, and it's a rhetorical one, if penstemons don'y hybridize in the wild much, but do a lot in the garden, then the obvious conclusion is that the plants are happier in the garden.

I'm not sure there is such a direct correlation.  In the garden, where one can amass a number of species in a small area, species that would otherwise never have the opportunity to be growing together, then the possibility of hybridization increases many fold.  Each genus of plants then has its own genetic persuasion that might enable or inhibit hybridization.  I'm no expert on Penstemon, but bring together members of Dasanthera within close proximity and the behold the promiscuity.  I have heard that hybridization between sections of Penstemon are highly unlikely.  It contrast, it is interesting that in a huge genus such as Allium, where similarly there are distinct "sections" of the genus that are quite different and separate from each other, studies on the genus have concluded that species from disparate sections of the genus are actually more accepting of hybridization than closely allied species.  I mostly agree with this finding based on personal experience.