Beginner gardener's guide to seedless plants reproduction

comments (0) July 30th, 2015

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CarolWilliams CarolWilliams, member
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If you're a gardener, even a beginning one, you've surely witnessed the miracle of a seed sprouting. I never get tired of coming out in the morning to find those tiny plants poking up from the soil!



But have you ever stopped to wonder about the fact that some plants, even many we know and love, actually have no seeds? It's true! Think about the banana you had at breakfast or the navel orange you had at lunch. Even watermelon's gone seedless in recent years, to my children's delight. And it's not just cultivated fruit...many plants, especially ancient species like ferns, mosses, and liverworts, reproduce without the help of a single seed.



How on earth does this work? There's not one single answer, but rather, many. For the curious, and those who've wondered if they can grow their own plants without using seed at home, here's a quick rundown.





First of does this normally work? Well, when a mommy plant loves a daddy plant very much...just kidding. It is a little bit like that, though, in the sense that typically, egg cells in the ovule (female parts) of a flower receive pollen from the male parts of a flower. The fertilized egg develops into a fruit with seeds.


In some plants, however, fruit can develop without fertilization and without seeds. Useful, huh? This is called parthenocarpy. The seedless navel oranges are an example of a parthenocarpic fruit.


But wait. Where did the first navel orange come from? And without seeds, how do we keep making more navel orange trees? Ah, good questions. The first navel orange came about as a "bud sport"-an odd mutation on a more typical seeded orange tree. The unique seedless fruit was noticed, and then propagated by a technique called grafting.





Grafting is a fascinating and ancient technique of "assisted plant reproduction." When we graft, we take a budding branch from one tree or plant and carefully attach it to another tree or plant of the same general species, using an adhesive or special material to keep them together. The branch then "takes" to the rootstock and makes a new tree with the characteristics of the graft. This is one way of perpetuating seedless plants and trees, and you can even try it at home.



Genetic engineering


You've probably noticed the rise of the seedless watermelon, which is certainly more enjoyable to eat than its seeded counterparts (unless you like seed-spitting contests). Where on earth did it come from? The answer is rather high-tech: plant breeders cross a "normal" watermelon, which possess two sets of chromosomes, with one with four sets of chromosomes (that's not normal) to create one with THREE sets of chromosomes (again, not normal). This hybrid, also called a triploid, is not "balanced" enough to set seed. This process has to be repeated for every generation since there is nothing to replant, but many consider the payoff worth it.


The bananas we commonly eat and enjoy are triploid, too. In their case, they continue to reproduce from side shoots, rather than their (nonexistent) seeds.





It's also possible to selectively breed seeded plants to create seedless or near-seedless variries. The Flame Seedless grape is an example of a seedless fruit created by long, hard work breeding and hybridizing (it is propagated by graft). This is most likely beyond the reach of any home gardener, though.



Other ancient methods of reproduction


Remember those ferns and mosses? Flowers, fruit, and seeds are actually relatively "new" innovations in the ancient world of plants. Before they came along, plants used other techniques to reproduce themselves, such as spores, rhizomes, and fragmentation.


I'll never lose my sense of wonder at seeing new sprouts peek up after I've planted seeds, but it's fascinating to learn about the other ways plants can reproduce without them. Nature and humankind are both infinitely inventive.




posted in: growing, fruits, Seedles