Camellias are a popular garden plant here in the South. They have waxy dark green leaves year round. Then just when you least expect it, they burst forth in boisterous blooms with an utter disregard for winter. It’s as if they have set their springtime alarm clocks a few months early. Other bulbs and seeds are patiently biding their time in the cool ground while the camellias revel in the sun, “Suck it daffodils!” The pictures in this post are camellias blooming in my yard now.
Of course, “The force that through the green fuse drives the flower” is also the destroyer of these camellias. Such early flowering is a dangerous lifestyle. The latest polar vortex has covered most of Louisiana in ice for the past 36 hours and, alas, now the flowers are all a pitiful freeze-damaged brown. Let’s hope our local camellias can bounce back because there will be a Camellia Society Show at the Burden Center February 8 – 9. For more information about growing camellias in Louisiana, visit the resources from the LSU AgCenter and Hammond Research Station websites below. There are many variety options available to southern gardeners of all different sizes and colors.
My peppermint-streaked camellias are an example of variegation (plant biology word of the day). There can be a couple of underlying reasons for variegation patterns- genetics or viral infection. Let’s talk genetics and leave viruses for another day. The differences in color pattern on my camellia petals are due to changes in pigment synthesis within individual cells. Some cells do not produce pigments leaving them white or only pale pink, while other cells can make the pigments giving them a dark pink color. Pigment production is controlled by the expression of pigment synthesis genes within the individual cells.
OK, that makes sense, but how do the flowers get their striped patterns? If the flowers were like fish, the differently pigmented cells would chase one another until the dark-colored cells were corralled into a striped pattern by lighter-colored cells. However, plant cells have rigid cell walls that keep them as stoic as the Sphinx.
So camellias are not like fish. Their color patterns are controlled by the genetic competence for pigment production of each cell as the flower develops. If the cells can make a functional version of the pigment synthesis gene, the pigment is produced. Cells without pigments have some kind of mutation in a gene responsible for the synthesis of the pigment, and they appear white or pale pink. Wait, don’t all cells within a single plant have the same genetic material? Yes, they do, but these mutations tend to be unstable. They can relatively easily revert from nonfunctional mutant back to normal within individual cells. Once the mutation has reverted, it is transmitted as those cells divide. If the genetic reversion occurs late during the development of the flower, only thin streaks of color along the petals in random stripes.
This is why plants are different from tigers, leopards and people. They can change their stripes, spots and patterns. Genetic reversion of the pigment mutation can occur much earlier in flower development yielding sectored flowers like these where half (or a quarter or three-quarters etc.) of the flower is pigmented. The genetic reversion could also have happened much earlier in the development of the branch of the shrub such that it yields flowers that are completely dark pink and adjacent branches bloom striped flowers.
So don’t confuse immobility with constancy. In this case, the least mobile organism has the greatest genetic and developmental plasticity.
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