Penstemon ambiguus

[Spiegel]

Some years ago along an Arizona  highway in the middle of nowhere, I saw Penstemon ambiguus in bloom and fell instantly in love.  The clumps were scattered and about 18" high in full bloom.  After taking many pictures (all slides, alas), I carefully noted the kind of soil in which it grew (sand, old sparkplugs, shredded bits of rubber from tire blowouts, sand, cigarette stubs).  I grew it from seed and ended up with half a dozen seedlings ready to plant.  They were  planted in different spots in the garden.  Three died quite quickly when we had rain on and off for several weeks.  Three made it in the sand bed but only one looked really strong.  That is the one that survives still in the sand bed (very coarse sand and nothing else).  It blooms each year and each year it looks better.  It's so different from any other penstemon I grow.  I think you can see the difference in the flower shape from the pictures, it's quite open and flat.  The flowers are large and very lovely.  The color looks the same as the wild plants I saw.  It is considered xeric but it is an example of why you should never listen when people say something won't grow in the northeast or wherever you happen to live - you never know when something will decide it's found a second home.

[Lori S.]

What a very unusual-looking penstemon!  I must give it a try one day!

[RickR]

I'll second the unusual comment.  At first glance, you'd never dream it could be a penstemon!

[Nold]

Penstemon ambiguus is indeed a xeric plant. The only thing that means is that it grows in dry locations in habitat. It definitely does not mean that it won't accept two to three times the amount of moisture it receives in the wild. (Otherwise, obviously, there would be massive plant deaths during exceptionally wet years, just as there are massive deaths during droughts for many species throughout the world.) In fact, if you give a xeric plant more water, it just grows bigger. 
There is a large, ancient colony adjacent to the parking lot of the motel in the center of Wray, in northeastern Colorado. (There are also plants in the highway median but they get mowed down every year.) This is almost the northern limit of the species; I'm surprised it doesn't make it into the Sandhills in Nebraska.
It's also probably the wettest part of its habitat; Wray receives most of its precipitation as thunderstorms from April to September.
Some botanists put this species in its own genus, Leiostemon, because of the salverform corolla, but P. utahensis has pretty much the same corolla shape, though smaller.

[Kelaidis]

Ann: I'm starting to get just a trifle peeved: you keep showing Western plants looking better in Wappinger Falls than in Denver.....harrrrumph!

[Barbara Weintraub]

Anne, you grow western natives beautifully! This is another penstemon that grows in northern New Mexico. The populations that I know of grow in SAND, so it's not just an east coast thing. I've killed it by trying to grow it in thicker, more clayey soil. Time to collect seed again and just throw it out in the one or two sandy areas of my property.

[Spiegel]

Ann: I'm starting to get just a trifle peeved: you keep showing Western plants looking better in Wappinger Falls than in Denver.....harrrrumph!

Panayoti, the difference is the struggle involved to find the right spot.  I also saw P. ambiguus growing in Moab and it was spectacular,  not like my slowly increasing example.  Astragalus tridactylicus is simply never going to do for me what is does in your garden, but when it blooms, I'm content just to have it.

[Spiegel]

Penstemon ambiguus is indeed a xeric plant. The only thing that means is that it grows in dry locations in habitat. It definitely does not mean that it won't accept two to three times the amount of moisture it receives in the wild. (Otherwise, obviously, there would be massive plant deaths during exceptionally wet years, just as there are massive deaths during droughts for many species throughout the world.) In fact, if you give a xeric plant more water, it just grows bigger.  
There is a large, ancient colony adjacent to the parking lot of the motel in the center of Wray, in northeastern Colorado. (There are also plants in the highway median but they get mowed down every year.) This is almost the northern limit of the species; I'm surprised it doesn't make it into the Sandhills in Nebraska.
It's also probably the wettest part of its habitat; Wray receives most of its precipitation as thunderstorms from April to September.
Some botanists put this species in its own genus, Leiostemon, because of the salverform corolla, but P. utahensis has pretty much the same corolla shape, though smaller.

Thanks for the information, Bob.  Your penstemon book is reread every winter when one can only dream about plants.  I agree with you about many of the xeric plants. Perhaps they grow where they are because of lack of competition or any number of other factors.  Most xeric plants seem to appreciate the extra water unless the drainage is poor.  I do take exception when it comes to xeric astragalus and other of the glorious peas.  We can have a weird combination of extended drought, heat and very high humidity.   Eriogonums thrive on it, western phlox don't seem to mind but astragalus can be really miffy in these circumstances.

[Spiegel]

Anne, you grow western natives beautifully! This is another penstemon that grows in northern New Mexico. The populations that I know of grow in SAND, so it's not just an east coast thing. I've killed it by trying to grow it in thicker, more clayey soil. Time to collect seed again and just throw it out in the one or two sandy areas of my property.

Lucky you, Barbara, to have a garden with altitude and in P.ambiguus territory! I've hiked in the Santa Fe area but spent all my time above treeline when possible. My hiking companion preferred bottoms where rattlesnakes were living, not my cup of tea.  Do you grow any of the peas?

[Weiser]

I just planted this in my garden about a month ago.  I purchased a one gallon potted plant, bare rooted it and planted it in a sandy planting pocket were it can steal a little water from a dripper that is located about a foot away. So far it looks good and is putting on growth. I also have a few seedlings started that I forgot I had sown, they are just past the two leaf stage, but will not be planted out until this fall when the temps moderate a little.

Thank you for showing me what to expect next year.

[Spiegel]

I just planted this in my garden about a month ago.  I purchased a one gallon potted plant, bare rooted it and planted it in a sandy planting pocket were it can steal a little water from a dripper that is located about a foot away. So far it looks good and is putting on growth. I also have a few seedlings started that I forgot I had sown, they are just past the two leaf stage, but will not be planted out until this fall when the temps moderate a little.

Thank you for showing me what to expect next year.

Wow! A one-gallon plant of Penstemon ambiguus! I think you'll have a great plant in no time.  How lucky to find something like this.

[Nold]

 I agree with you about many of the xeric plants. Perhaps they grow where they are because of lack of competition or any number of other factors.  Most xeric plants seem to appreciate the extra water unless the drainage is poor.  I do take exception when it comes to xeric astragalus and other of the glorious peas.  

That's in New York, though. In climates that fairly closely replicate those of western dryland plants (excluding the west coast), there is no known upper limit to the amount of moisture the plants will accept during the growing season. If there were, the plants would all have been extinct long ago.
Never mind that xeriscapers claim that that some western plants can get "too much water".
If all other factors are the same (ie intense sunlight, low humidity, etc), a xeric plant will just get bigger and bigger if it's watered.
What I wonder is why people, especially rock gardeners, accept the notion that a plant's habitat determines its cultivation. Obvious generalizations like sun/shade or winter cold aside, this is true for almost no plant anywhere. You can grow these plants better than I can.
I'll just go mope in my hundred-ice-plant rock garden now.

[Weiser]

Bob

I'll just go mope in my hundred-ice-plant rock garden now.

You poor fellow!!

To be relegated to mope in such a dismal pace.

We should all be so lucky!!

[Hugh MacMillan]

Penstemon ambiguus is indeed a xeric plant. The only thing that means is that it grows in dry locations in habitat. It definitely does not mean that it won't accept two to three times the amount of moisture it receives in the wild. (Otherwise, obviously, there would be massive plant deaths during exceptionally wet years, just as there are massive deaths during droughts for many species throughout the world.) In fact, if you give a xeric plant more water, it just grows bigger. 

I agree with Bob - The attached picture was taken June, 2008,  just off of Highway 276 in Utah, a few miles east of Halls Crossing.  As you can see, the habitat is very dry.  The P. ambiguus in my garden watered perhaps 3 to 4 times a year but our average rainfall is considerably more than in the Utah location. 

In September 2009, in the Samalayuca sand dunes in Chihuahua, Mexico I witnessed another P. ambiguus but of a considerably lighter flower color.  Interesgtingly enough, the sands of Samalayuca are near white whereas the sands of the Utah location are brick red.  Oh, had I collected seed in Mexico!

[Nold]

Oh, had you collected seed, indeed.
So ambiguus grows in sand in the wild. All that means to me is that the species has found sand to be a viable medium for germinating its seed. It has no reason to try growing elsewhere. Plants can be lazy too.
The related P. thurberi was a disappointment here. It bloomed, etc., but died of drought. Apparently it needs a monsoon, which I can't provide expect in the form of an overhead sprinkler.