Tucson is a great place to get outdoors, bask in the warm sun, and do some exploring. I took the opportunity to do some hiking with my undergraduate lab while I was back in town for Thanksgiving. We explored the Tucson Mountain range, not too far from the University of Arizona.
While checking out some small caves a short hike from the trail, we discovered the awesome cave paintings of the Black Sheep Pictograph Site. These paintings of deer and big horn sheep have been well preserved in a small cave along a mountainous slope. These were painted by the Hohokam who inhabited the Tucson Valley; it seems like these animals must have been valuable food sources, yet I'm more curious about which plants they might have foraged for.
Camelina is certainly a very interesting system for studying evolution, and much work has been done in it, although the majority of this work was done in the early 20th century in the U.S.S.R. and has yet to be rediscovered in the West.
Ivan Schmalhausen was a Ukrainian born, Soviet evolutionary biologist, whose work was largely disregarded in the U.S.S.R. due to the subduing of ideas that digressed from Lysenkoism. Schmalhausen used the term "norm of reaction", originally conceptualized by the German, Richard Wolterck, to explain how genotypes can react to the environment to vary phenotype. He used Camelina as an example of this, as C. glabrata (now recognized as C. sativa), shows a tall, slender morphology when planted in flax fields. He claimed that the tall structure, narrow leaves and long internodes of another "species", C. linicola (now C. alyssum), were stabilized through genetic fixation, while these are plastic characters in C. glabrata. Nikolai Wasiljevich Zinger, a Russian botanist, worked on Camelina in his little known paper "On the Species Camelina and Spergula Which Infest Flax Sowings and Their Origin". Zinger's figure, shown below, illustrates the norm of reaction in both of these Camelina varieties, where, when sown densely (or with flax) they adapt a tall, slender morphology, and when planted alone they branch and increase overall density of leaves and fruits. However, the stabilizing selection that acted on C. linicola as a flax weed can be noticed, as when grown alone it retains its narrow leaves and sparse habit compared to C. glabrata. Schmalhausen used this example as evidence that some physical forms can be under dynamic selection, as seen by Camelina changing morphology based on its environment (5a to 6a and 1a to 8a), while some traits become stabilized and are no longer subject to change by environment, like those in C. linicola of slender leaves and sparse growth when compared to C. glabrata under "wild" circumstances (6a to 8a).
Zinger also noted that the selection of seed size in C. linicola was dynamic, meaning that the size were readily changed, although able to revert. The process of winnowing (separating the seeds from plant material) in flax, unintentionally selects for Camelina seeds which are larger in size so as to mimic flax seeds, and in doing so are planted with the next season's flax crop. Schmalhausen recognized this dynamic selection as labile, meaning that the variable trait is not fixed, and is phenotypically plastic depending on environmental factors.
Schmalhausen claimed that the propensity for Camelina to adapt rapidly to new environments was due to a "preceeding preparatory evolution". I would attribute this to C. sativa's polyploid status which gives it a large "tool set" for adaptation and rapid evolution, which has allowed the colonization of new geographies (temperate, mesic environments) and specific niches (flax fields).
Schmalhausen, I. I. 1949. Factors of Evolution. Blakiston, Philadelphia. (pp 1-95)
Google's Ngram viewer is a tool which shows prevalence of words used in Google's collection of digitized books. The graph above represents the percent usage of several common names of Camelina sativa (Gold of pleasure or false flax). What is particularly striking about this graph is the higher usage of "Camelina" in literature of the 1800's, with a steady decline for the last 60 years, and now it's starting to increase in use again. This highlights the fact that Camelina fell out of favor as an oil seed crop during the 1900's, only recently to be recognized as a viable biofuel crop. It is also clear that "gold of pleasure" was most widely used around 1780-1900, whereas "false flax" became a popular common name from about 1900-1960. Now, it seems that there is an even split between the two common names "gold of pleasure" and "false flax".
Above is a graph of the use of "Camelina" and its German common name "Leindotter", which appear to be used interchangeably in German literature. These trends reflect those of the English names; there is a slight reduction in use, but this time starting in the 1920's, and following through until about the 1980's when a resurgence of "Leindotter" occurred.
While Camelina cultivation halted around the early 1900's in most Western nations, Russia continued to experiment using the cruciferous oil seed. This is reflected by the usage of the Russian word for Camelina (Рыжик), which only started to be used after 1900, and reached a peak around 1940-1980, this corresponds to the time in which usage of "Camelina" was decreasing in the West. Camelina is still grown in Eastern Europe and parts of Russia, but I'm not certain of the extent of use or what the applications are (other than as a cooking oil).
The prevalence of the word Camelina is much higher in Russia (although I'm sure there could be many biases responsible for this). During the 1960's, use in Russia was at about 0.000045%, whereas the same period in English literature, only 0.0000015%, or put another way, during this time Camelina was mentioned in Russian language books 30 times more than English language books.