Camp Pendleton Brodiaeas
Wayne's WordIndexNoteworthy PlantsTriviaLemnaceaeBiology 101BotanySearch
 Brodiaea Index   Brodiaea Key   San Marcos Vernal Pools   Brodiaea jolonensis?   Brodiaeas in San Marcos   BTK Citations In Floras 
Staminode Variation in Camp Pendleton BTK
Themidaceae: Brodiaea terrestris ssp. kernensis (Coastal BTK)

© W.P. Armstrong 5 May 2009

Brodiaea terrestris ssp. kernensis (BTK), including coastal & montane forms, is a large and diverse complex that extends from Santa Barbara and Kern Counties to the Mexican border. Data from Principal Components Analysis (PCA) thus far indicates that BTK is one variable species that does not warrant segregation. BTK intergrades into variable populations on the Santa Rosa Plateau of Riverside County and at Cuyamaca Lake and Camp Pendleton in San Diego County. Fertile clonal variants have hooded staminodes, staminodes that are flattened and strap-shaped or inrolled along upper margins, and narrow staminodes that are tapered toward the apex. In addition, the staminodes may be erect, leaning slightly outward or leaning inward. Whether the anther connectives of BTK have a dentate appendage or V-shaped notch is also quite variable, particularly in Kern County populations. This trait is of little value in separating populations of BTK, but is fairly consistent in populations of B. terrestris ssp. terrestris (BTT) in San Luis Obispo and Monterey Counties. In general, populations of BTK in southern California lack a well-defined dentate connective; however, this trait occurs in some Kern County populations. These traits are apparently not under selection pressure and hence exhibit a lot of variability. In addition to clonal variants, there are occasional sterile hybrids between BTK and other sympatric populations, such as B. filifolia and B. orcuttii.

Brodiaea species in general exhibit considerable variation in staminode shape and size, which often makes field identification difficult. This is especially true of coastal populations of BTK in southern California, formerly assigned to the taxon B. jolonensis. In fact, local clonal populations may have staminodes quite distinctive from nearby populations. Cross pollination between sympatric species also results in hybrids with intermediate staminodes. Hybrids between parents with different chromosome numbers, such as BTK and B. filifolia or B. orcuttii, are typically sterile and do not produce viable pollen.

Staminodes Superficially Approaching The Shape & Size of Brodiaea filifolia

The staminodes of this flower are superficially similar to those of B. filifolia. However, the staminodes are longer than any sample of B. filifolia we have examined; they do not have the gradually tapered shape of the staminodes of that species; and they are more erect than typical B. filifolia staminodes. The staminodes have the basic oblong shape of those of BTK, with tapering toward the apex in two or three stages. They also have the typical purple color of BTK, and not the white of B. filifolia. See the next image.

The staminode of this flower (white arrow) is flattened and tapered toward the tip. It is similar to clonal variants of BTK in San Marcos (see next image).

Staminode variation in San Marcos: A. Typical coastal BTK with hooded staminodes. B. BTK variant with slender, tapered, strap-shaped staminodes. C. Typical B. filifolia with filiform staminodes. I originally thought this BTK variant was a hybrid between BTK and B. filifolia; however, it is fertile and quite different from the true sterile hybrid. In addition, its diploid chromosome number is at least 36, higher than an expected hybrid between these two species.

This is a hybrid between Coastal BTK (Brodiaea terrestris ssp. kernensis) and B. filifolia or B. orcuttii which occur nearby. Note the strap-shaped staminodes that are not hooded as in typical coastal BTK. The flower was completely sterile with no mature pollen grains, giving credibility to the hybrid hypothesis. The clear liquid inside the reduced anther sacs contained cellular debris and scattered nuclei, but no well-formed pollen grains.

  Sterile BTK Hybrid With Flat Staminodes  
Possible Origin Of The Sterile Hybrid
Fertile B. filifolia x B. orcuttii Hybrid
Brodiaea orcuttii in San Marcos
Brodiaea filifolia in San Marcos

Fertile Hybrid Between Brodiaea orcuttii x B. filifolia (San Marcos)

San Marcos Brodiaea filifolia x B. orcuttii hybrid showing slender, erect staminodes. The filiform staminodes resemble B. filifolia, but the long filaments resemble B. orcuttii.

Erect, Strap-Shaped Non-Hooded Staminodes

The staminodes of this flower are erect, flat (non-inrolled) and non-hooded. They are similar to populations of montane BTK on the Santa Rosa Plateau, Cuyamaca Lake and Kern County.
Brodiaea terrestris ssp. kernensis from Kern County. The staminodes are slightly inrolled along upper margins but not hooded. In general, they superficially resemble populations of Montane BTK in the Laguna Mts. of San Diego County. The anther connectives are not dentate; however, connectives in Kern County are variable and range from an entire V-shaped notch to a definite dentate lobe.
  Staminode Variation Of BTK On Santa Rosa Plateau  
Staminode Variation Of BTK At Cuyamaca Lake

Erect, Hooded Staminodes

The staminodes of this flower are erect and hooded, typical of coastal populations of BTK in San Diego County California, including San Marcos and Otay Mesa (see next image).

Coastal BTK (Brodiaea terrestris ssp. kernensis). The grass is false brome (Brachypodium distachyon), a naturalized annual from southern Europe.

  Coastal BTK in San Marcos  

A Camouflaged Horned Lizard (Phrynosoma coronatum)

Return To WAYNE'S WORD Home Page
Go To Biology GEE WHIZ TRIVIA Page