Fruits and Their Reproduction: Seed and Clonal Methods
The wonderful variety of fruits available in markets around the world is not simply a product of artificial selection and genetic engineering. Many fruits reproduce naturally through two primary methods: seed reproduction and clonal reproduction.
Seed Reproduction: The Natural Way of Reproducing
Seed reproduction is the “normal” way of reproducing a fruit-bearing plant. To achieve this, one collects the seeds from a fruit, extracts them, and plants them to grow a new plant. This process is familiar to many who have planted gardens, as seen in tomatoes and okra, which are both botanical fruits, albeit with a savory flavor rather than sweetness.
Scarification: A Special Step for Some Seeds
However, for many fruits, this process is a bit more complex. Examples of this include raspberries, blackberries, and other brambleberries, which require a process called scarification. Scarification involves lightly breaking apart the outer coating of a seed. In nature, this occurs when seeds are ingested by animals. The acids in animal stomachs help soften the seed’s outer shell, facilitating its proper germination.
In colder regions, seeds also undergo natural scarification during the winter season. As the ground shifts due to freezing and thawing, the tiny seed undergoes mechanical scarification, preparing it to sprout in the spring.
Clonal Reproduction: A Mirroring of the Plant
Clonal reproduction is another method by which fruits can be reproduced. This occurs when a cutting of mature plant tissue—a piece of branch, leaf, or root—grows into a new plant whole and entire. Many plants can achieve this naturally, such as African violets, which can be grown from a single leaf placed in water until it sprouts roots.
Some plants have evolved to reproduce clonally deliberately, as is the case with strawberries. These plants produce special stems called stolons or runners, which grow away from the main stem to eventually plant themselves and grow into new plants. This means that one fruit plant can, with enough time, grow a whole strawberry patch by tending to and giving space to the runners.
Advantages and Limitations of Clonal Reproduction
The benefit of clonal reproduction is that child plants have only one parent, making them nearly identical to the mother plant. Species like Granny Smith apples and nearly all bananas can be propagated only through clonal cuttings, as they are successful genetic replicas. This method is akin to replicating a prize milking cow, cutting off one horn, and growing a new cow that is just as productive.
This means that for fruits like Granny Smith apples and strawberries, it is statistically very difficult to produce a fruit that looks exactly the same by planting the seeds, as doing so may yield a wild type of apple or strawberry far smaller in size.
Why Some Fruits Can't Be Reproduced from Seeds
Some clonally-reproducing plants, like bananas, can only be reproduced through cuttings and not from seeds. This is often due to the fact that these plants have no seeds. The reason for this lack of seeds is typically because they are hybrids between two incompatible types, akin to a plant version of a mule. Bananas, for example, are sterile mules because they have three sets of chromosomes, which creates an uneven genetic code that typically interferes with seed production.
From raspberries and blackberries to bananas and strawberries, the journey from seed to fruit is a fascinating one filled with natural processes and selective cultivation. Understanding these methods can help gardeners and farmers alike to cultivate and propagate a wider variety of fruits.