Utah Oxytropis?

[Jane Hendrix]

I found this lovely, compact species growing in widely-scattered colonies in the Uinta Mountains, Uintah County, Utah, blooming on May 21, 2009.  I was in the area of Brush Creek Canyon Overlook at an elevation of between 8,400 and 8,700 feet in large, open meadows ringed by aspen groves.  I don't know if it is, indeed, an Oxytropis but it is definitely in Fabaceae.  Can you help me put a name to my photos?

[McDonough]

Hi Jane,

Sorry but I don't have an ID suggestion, just wanted to say what a lovely plant it is; I'm going to sit back to see if anyone else knows its name.

[Gordon]

Might it be Astragalus lentiginosus? Just a guess on my part, check this- http://intermountainbiota.org/portal/taxa/index.php?taxon=4111&taxauthid=1&proj=10

[Spiegel]

Jane, from your pictures, not an oxytropis.  Astragalus and Trifolium are candidates.

[Jane Hendrix]

Could it be Astragalus spatulatus?  Here's a link to a herbarium specimen

http://herbarium.uvu.edu/virtual/search.asp?p=6&s=form&n=&o=Family,G.Genus,SpecificEpithet,InfraspecificName&l=%28%28%28GeoTertiaryDivision%29=%27Daggett%20County%27%29%29&t=County=%27Daggett%20County%27&cc=n&ce=n&cf=y&cg=y&cl=y&ct=y&cy=n&m=utahsmall

This specimen was collected in the same general area I was in when I photographed this plant.

[McDonough]

Jane, I think you got it, I agree it looks like Astragalus spathulatus.  Here are some image links:

http://www.easterncoloradowildflowers.com/Astragalus_spatulatus.htm
http://pdpratt.blogspot.com/2009/06/cypress-hills.html
http://www.em.ca/garden/native/nat_astragalus_spatulatus.html

[Hoy]

It is a pretty plant, anyway!

[Weiser]

Very nice and such a prolific bloomer!! Would be well worth growing.

[RickR]

Are there particular characteristics that point to one genus or the other, or disqualify oxytropis in this case?

[Weiser]

In flower one of the easier to see differences is that in Oxytropis, the keel tip is beaked. In other words notched and not smoothly curved. They may have just the sightest notch or break in the curve in some species. In others species a more pronounced deeper cleft is displayed, so that it  seems to have a distinct lobe protruding from the edge of the keel tip.

I hope I described this well.

[Lori S.]

Examples... (and please correct me if I'm wrong):
Beaked keel on Oxytropis viscida and Oxytropis megalantha:
 

Rounded keel on Astragalus angustifolius:


NB.  To expose the keel for a clear look, pull apart the two side petals that enclose it.

[Weiser]

Excellent examples Lori. The beaks are very well defined in your shots. Just be aware that they can be more subtle in some species. I hope this next example is large enough to view.

[RickR]

Very cool.    Thanks so much!

Anything else?

[Lori S.]

The beaks are very well defined in your shots. Just be aware that they can be more subtle in some species.

Good thing the ones I've looked at happened to be well defined ones!  
I'd like to know what to watch out for on the more subtle ones.  On the one you show, I'm not entirely clear on where the beak or notch is (versus the two petals that flank the keel), so I hope you don't mind that I have copied and annotated your photo (below) to ask my question... Is the notch/beak the bit outlined in blue (immediately left of the red arrow)?  (Or is the structure the blue arrow is touching?)

[Weiser]

Lori
You are correct with the first outlined section. The red Arrow is pointing directly at the notch along the keel edge. It is not a sharp V shaped notch, I would describe it more as a slight in curving of the keel edge (An interuption to arc, so to speak) which then flares out slightly again, creating a lobe (or Beak) at the tip of the Keel.

By the way I have this ID-ed as Oxytropis borealis. Possibly (var. australis?) which is the variety found in the Sierra Nevada Range.