Transition Studies in  Flowering Plants 
by Rolf Baumberger

Field Investigations 2019

Spring 2019 SMER
Ideal flower shoot of Diplacus puniceus. The flower buds are red (b) and do not change their color after blooming (ea) or later (la). Anthesis about ten days.

A transition at the Santa Susana Pass (Chatsworth, LA County) 

Diplacus longiflorus with large yellow flowers transforms gradually into Diplacus rutilus with burgundy flowers. Monitory is effected every five years. Affected are both the flower color and the flower shape. The process is hereditary and sustainable.

Almost bowl shaped plants

The tagged plant 940 has become much darker wine-red flowers that show less flitting than a year before.

Beginning and end stage of the transition from Diplacus longiflorus to Diplacus rutilus.

The process is observed on perennial plants along the Santa Susana Pass. It is currently being repeated a hundredfold on plants at the wilderness site. Typical is a particular state of flitting. 

The once transformed orange colored flower changes in the course of anthesis back to the original yellow form. In this condition, the plant has the potential to express both forms phenotypically. However, this is only the case in the transitional state. Later in the transition, the plant loses this property and then only has burgundy flowers.This vegetative process takes years to complete. The result is, however, a new hereditary and sustainable shape. (Speciation

Only a handful of plant individuals have reached the final stage and have maroon or burgundy, narrow and long blooms. It is worth seeing these specimens - from the end of April 2019 at Stoney Point Peak. - The author will also look around in this area and even outside this zone.

Distribution of D. rutilus mixed and D. longiflorus
Burgundy flowered rutilus plants are mainly found on the North flank of Stoney Point Park and scattered NE of it. Heading West, there are mixed populations seen shifting to pure yellow populations at Santa Susana parking. The progression of transition is considerable high. The plants alter their morphotypes significantly within one year.

 A transition at the Santa Ana Mountains above 1000 m of Elevation (cf. Fig.1:E)

One of the strangest and fastest transformations that the author has ever seen is that of Diplacus calycinus individuals in the upper reaches of the Santa Ana Mts. Richard M. Beeks reported in 1961 on this taxon and mentioned the exact geographic location of the populations. Since about 2010, these populations change quite abruptly.
The author wants to see as many original populations as possible (D. calycinus) this year and also looks at where transitions take place everywhere. From D. calycinus does not arise just D. puniceus but a new shape with orange-red flowers. On the results, one can be even more excited. 


Unfortunately, the recent bush fire (2018) has destroyed two more monitory populations in transition. Additionally, there is no current access to the remaining region above 1000 m altitude where these morphs may occur.