A Matter of Selection

         Over many years, brassica oleracea have evolved into many different species. Sometimes it might even be difficult to notice that the plants are from the same family. Over the past week, I performed some research on the brassica oleracea species growing in the WGHS GOLD Garden. Surprisingly, the largest variation in characteristic between all the plants were the leaves. The greatest range of variation was also seen between the leaves.

KOHLRABI:
Leaves-

• 34 cm long, 20.5 cm wide
• dark green
• spread far apart from each other
• purple stems

SIBERIAN KALE:
Leaves-
 

• 27.5 cm long, 13 cm wide
• rough texture, ruffled edges
• dark green leaves, bright purple stem
• purple stems

DINO KALE:
Leaves-

• 38 cm long, 8 cm wide
• very dark green
• narrow
• textured leaves
• light green stem

CABBAGE (green):
Leaves-

• 26.4 cm long, 18 cm wide
• close together
• medium green color
• light green stem
  

BROCCOLI:

Leaves-

• 27 cm long, 16 cm wide
• medium green 
• spread apart
• light green stem
  

PURPLE CABBAGE:

Leaves-

• 19 cm long, 17 cm wide
• close together
• purple leaves and stem

CAULIFLOWER:

Leaves-

• 25 cm long, 11 cm wide
• leaves fairly close together, but as the plant grows taller, flowers spread farther apart
• light green leaves and stem

        As the data above shows,  the variations among the leaf characteristics (size/shape) are very large. There is the cauliflower with short narrow leaves, the kale with ruffled edges, and the cabbages with wide leaves close together. The characteristic that exhibits the greatest number of variations was the appearance of the leaves. The largest range of variation is the size of the overall plant. The cabbages only grow to be a few feet tall, but the broccoli grow twice that height.

       All of these plants are so different because over time, their genes changed to become accustomed to new environments. Humans might also have caused artificial selection among the plants over time. They modified plants' genes to produce a desired outcome. For example, naturally, cauliflower and broccoli usually don't have their flower buds so compressed together. However, over time humans changed these plants to have the flower buds close together to create a "little tree." This type of selective breeding has produced different forms of brassica oleracea. Even though most plants today are modified in some way, plants can also evolve into different species through descent with modification. If a plant is forced to adapt to a new environment or an unpredictable change in population occurs, one type of plant or trait within a species might become the more dominant gene. When the offspring are bred, they have a high chance of not being exactly the same as their parents. Their genes will have shifted to accommodate new changes and this process is repeated through all generations. With natural variations, mutations can occur and this is also a reason why the plants become so different. 

      The color of the plants were the most consistent because they are all close together in shades of green. They go from light green to dark green, then gradually change to purple. All of these colors are similar in some way. The anatomy of the plant that is the most the same is the bulb of the bottom of the plants. They are all about 15 cm across and 10 cm tall. All of these bulbs are above the soil and thick and round. The only difference is the color of the bulb. 

      In order to get the characteristics breeders want in plants, they use modern technology to find the traits inside other plants and transfer them into the desired plant. Once they find the trait and it is implanted into the plant, they have to multiply their supply of this new mutation. This process, selective breeding or artificial selection, produces a new variation of an old plant. Scientists are able to do this fro any trait.