Monday, March 28, 2011

Getting Freaky in the Plant Kingdom...

I have heard on occasion (usually after my wife spends the day cleaning, washing clothes, doing laundry, and caring for our son!) that if women could figure out how to fertilize themselves, the male sex would be obsolete due to natural selection against worthlessness. Not only do plants reproduce sexually, but some also have a neat little trick up their stalks. Certain species of plants have the ability to reproduce asexually, without the genetic contribution of a neighbor. Great trick. Just don't tell my wife. Lets face it, plant reproduction isn't necessarily the most pressing issue on most of our minds right? I mean, how many of us realize on those gorgeous spring days when we can barely breathe due to our bodies reacting against the massive plant sperm overdose we have been subjected to. Uh, gross... 

Sexual reproduction in all land plants involves alternation of generations. This means that their life cycle is split into two distinct phases; one in which the genetic information is haploid, and the other in which the genetic information is diploid. There are differing details for different organisms, but the main idea is the same. Alternation of generations begins when two haploid gametes fuse to form a diploid zygote, which will divide by mitosis to form a viable diploid organism called a sporophyte. After maturation, the sporophyte develops one or more sporangia, which are the sexual organs that develop the haploid spore cells through meiosis. The spore cells then are able to divide by mitosis into a gametophyte that divides by mitosis, and thus gives rise to the haploid gametes capable of fusing together into another diploid cell, and thus repeating the cycle. A very complex cycle, and one that is necessary in order for plants to exchange genetic information.

Asexual reproduction skips the awkward movie and dinner approach to plant reproduction, and skips right to the good stuff... making progeny. Some plants such as the Kalanchoe, are able to form little plantlets from their leaves, while others such as silverweed, uses stolons, or horizontal connections between organisms to spread viable offspring. Plants such as Euphorbia and Ginger use rhizomes, which originate from the main stem of the organisms, and crawl laterally in order to shoot roots from the nodes, and effectively spread itself. Two other methods of asexual reproduction are through the use of bulbs and tubers, like tulips, and potatoes respectively. Another form is called apomixis, which essentially replaces normal sexual reproduction with asexual reproduction. In other words, sporophytes are able to be formed without fertilization This form is particularly important in ferns and flowering plants. The catch here is that plants who produce asexually these ways form clonal colonies, which contain essentially the same genetic information within the group.

It is truly remarkable how many adaptive ways of reproduction are displayed in the plant kingdom. So, think again if you were under the impression that you were a sexually talented being, and realize that you have been outdone for millions of years. Plants are truly the overachievers who are well beyond the constraints of gender specified reproduction. 

2 comments:

  1. I like the title of this! haha

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  2. lol I was so late 4 a project about how plants reproduce and this helped me so much u got me an 100,lol thank u

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