by Rolf Baumberger 

Santa Susana Pass Transition

A worth seeing transition zone has formed along the Santa Susana Pass.

If you want to see them, go first to Stoney Point Park and look around (A). In the shadow of the stone blocks grows Diplacus rutilus (It starts flowering from the middle to the end of April). Then head west on the Santa Susana Pass to the South (B) car park.

From there you walk back to the gate (C) and go to the circular route. At the height of (D), you will see a series of Diplacus plants in transition. TZ= current transition zone is moving to the West.

34.267222, -118.623056

If you head back and hike to the hummingbird trail, you will see yellow flowering D. longiflorus (E) there. The transition zone is currently between A <----> B. It moves slowly to the west.

Here you can mark individual plants permanently and monitor these over time (3-5 years). See if they change phenotypically or not. Both trails are open to the public. 

  • 940-18
  • 940-19
  • 940-22A
  • SSP1-
  • Stoneybud
  • Rut01
  • Rut02


Diplacus rutilus grows mainly in the shade of large boulders in this summer dry landscape. It turns out that the branches of this plant shorten this way, that the bush takes on a spherical shape. The transition takes about ten to fifteen years. D. rutilus develops from Diplacus longiflorus (calycinus?) plant individuals (color phase space). D. rutilus, in its cushion shape, originated around the year 2010

The tagged plant # 940 shows a significant floral color shift towards the dark rutilus type in a couple of years only (18-22). Every year flower shape of 10-50 adult plants becomes rutilus-like in the area. Also, here we have species formation on the fly.


 The phenomenon origins at Stoney point and spreads out from there.

05-27-22 rolfy