Fulfilling my obligation

I don’t know why I feel a sense of moral obligation to write about corn every summer, and especially about the process of fertilization in that organism, but I do. Perhaps it is because so many of my students know so little about the plant and about the process. Not only are many unaware that corn is monoecious, a single plant has both male and female parts, but many more are clueless as to what these parts are called, where they are, and how corn plants actually do it. So indulge me as I discharge my obligation to the thinking world. To begin with, the tassel at the very top of the plant is part of the male reproductive system and is responsible for the production of pollen. Pollen transports sperm to fertilize the egg which resides within the kernel; but how does the former reach the latter which is sequestered deep within the ear? The solution is that each developing egg grows, from within its protective and nourishing kernel, a tube which we call silk. The silk connects the egg, within the kernel, to the outside world. When a pollen grain, released from one of hundreds of anthers on the tassel, lands on the tip of a piece of silk it will germinate and grow a pollen tube which will allow the male reproductive nucleus access to the egg, and voilá, fertilization will be achieved. It is in this way that an ear of corn may correctly be viewed as so many corn-babies, each resulting from the fertilization of an egg cell by a sperm cell. The images below show a mature tassel; a closer view of a single tassel spike, with all of its colorful anthers; an ear of corn with its characteristic tuft of silk; and an undeveloped ear which has had its husk removed, allowing you to see that each developing kernel has a tube of silk emerging from its surface. So, what about the last three images? What do they have to do with corn reproduction? The interesting machine is a detasseler, a high-clearance tractor which supports eight rotating blades which are adjusted to ride just below the lowest point of the tassel. And, why would anyone want to detassel a field of corn plants? To produce, in a very controlled way, a hybrid corn crop of course. The key to producing hybrid plants is in the planting of the field and in the selective detasseling of individuals. The field is sowed to two varieties, every fifth row is planted to a variety that will act male while the other four rows are planted to a different variety that will act female. The plants in the female rows are detasseled and then harvested later as the primary crop (the tasseled, male, plants will be harvested as animal feed). Detasseling produces the characteristic notched pattern of fields planted in this way that you may have seen while traveling along an adjacent highway. Because of variation in the height of individual plants, the process of machine detasseling is only 80-90% effective and the remaining tassels must be removed by hand. You may be aware that a large number of young people across this country and across the globe are put to work for a short period of time each summer walking the fields in search of tassels which have been left behind and which they then remove by hand. Check out this article from Modern Farmer Magazine which describes the subculture of teen-detasselers in St. Joseph County, Michigan; and thanks to Lori Potter at potterspix for the nice shot of a crew of Nebraska detasselers. Now, the answer to the question of why one would want to produce hybrid corn is, hybrid vigor, which is both self-explanatory and a topic for yet another day.

9 thoughts on “Fulfilling my obligation

  1. You don’t see much corn up my way. First, only around 5% of the total land on the island can be cultivated (glaciation removed much of the soil and what remains is far too sour for anything but boreal forest and stuff that likes bogs; great berries, though) and and, second, we only get barely the required minimum number of days of sunshine for most varieties. A good friend of mine sets some each year – two varieties – but it tends to be touch and go. Lovely pictures and informative too 🙂

    • Hey! Glad you’re back. There was no need for you to review and comment upon all that I’ve done in your absence. Really, no need. But (don’t tell Maurice) I was glad indeed to see that you wanted to catch up. How was the trip? I’m expecting some nice images of sheep! D

      • I passed quite a few flocks of sheep but, sadly, it was always from a train or a bus so I did not take photos. I did, however, get a chance to observe quite a few different breeds and was quite interested in the patterns with which they inhabit the pastures. But it’s late, I’m up too long and more than a little jet lagged. More in a bit.

  2. I can remember last year’s article, I commented about our male/female tree. Believe it or not, I was thinking of that conversation 1-2 weeks ago when I again saw both red and white blossoms. The photo “corn3” is my favorite. Now I see a face where there is none – the tassel looks like the hair-do of a cartoon blond 🙂

  3. Oh my, I think corn smut may need a new definition. 😳 Seriously, although I did understand how corn reproduction, you brought it all together well. It is amazing to learn the variety of ways that species, other than humans, reproduce. Some of the most unusual strategies may be found among the insects, but the variety of ways plants attract pollinators is just as mind boggling. Unless, of course, they are do-it-yourselfers, like corn. I had not read “The Pairodox Philosophy” previously. But I just did and it answered my question about the origin of the name Pairodox.

    • Ha! I hadn’t thought of the play-on-words involving Corn Smut … you seem to have beat me to that one! If you asked about the origin of Pairodox in a previous comment Steve, I must have overlooked it, please forgive me. Many folks are indeed confused by the name. When we first coined the name my mother was convinced, for a while, the we had named our farm Pair-of-ducks! I read, in the description which accompanies your Gravatar, that you are a fancier of the fungi among, of course, most other things. You may there be interested in a post I wrote some time ago about ballistic spore dispersal (http://wp.me/p1yRFa-3Da) in the fungi. Thanks again for your interest and for taking the time to view, read, and comment. D

      • It was in my reply to your comment on today’s post. It also took me a while to figure out that the “D” at the end of your comments is your initial … originally I thought it was a smile. The world is filled with worse assumptions. Had I not mentioned the play on words, I am willing to bet that Steve Schwartzman would have. Pair of Ducks would be a natural mistake for anyone to make. Thanks for the link … I will definitely take a gander.

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