It’s spring, and a young man’s fancy turns to … seeds.

“Seeding” is a way of creating a tournament “draw” that is not random. A random draw might pit the best players or teams too early, so that many of the following matches would be less exciting, since the top “seed” would be likely to dominate.

“Seeding” leads to those ubiquitous brackets, which do look a bit like a plant that is growing in reverse—starting out with lots of branches and ending in a single stem.

The practice of “seeding” apparently began in tennis, and in the United States. The Oxford English Dictionary quotes a January 1898 issue of American Lawn Tennis as saying “Several years ago, it was decided to ‘seed’ the best players through the championship draw, and this was done for two or three years.” A 1900 issue of Spalding’s Lawn Tennis Annual says: “It is generally advisable to ‘seed’ the draw in handicap tournaments so that the players in each class shall be separated as far as possible one from another.”

While the top-ranked player or team is also often the top “seeded,” ranking and seeding are actually separate calculations. “Seed” determination uses ranking as a basis, but may also include such variables as the surface where the tournament will be played or the history of a team or player in that tournament. And math is involved. Here is the determination for the 2011 men’s singles draw at Wimbledon, which is played on grass:

Step 1: Count the ATP [Association of Tennis Professionals] ranking points of each player as of June 13, 2011;

Step 2: Add all of the points that a player has earned in any grass court events in the past 12 months on top of that; and

Step 3: Add another 75% of a player’s BEST grass court result in the 12 months BEFORE that to make a new total number of points.

The top seeds are “planted” in different divisions, so that, in theory, if all prevail, the No. 1 and No. 2 seeds will meet in the finals. Of course, there are upsets, which, one hopes, makes the tournament more exciting and less predictable.

Perhaps the most visible use of “seeding” after tennis is in collegiate basketball. Until 1979, the National Collegiate Athletic Association, which runs the “March Madness” basketball tournament, did not seed teams; that year it expanded to 40 teams, from 32, and seeding made more sense. In 2002, the tournament, then at 64 teams, developed a system to keep the top seeds closer to home for the first two rounds. It’s called the “pod” system. A “pod” has a lot of “seeds” in it. Get it?

“Seeding” works best when there are a lot of teams or players in a tournament, though professional baseball and football also use modified seeding for their playoffs. This year, Major League Baseball is expanding its playoffs, so that five teams in each league will be in the playoffs, instead of four. Two wild card teams in each league will play each other in a one-game playoff; the winner will face the top-seeded team in each league’s division series.

Of course, since there are just sixteen teams in the National League and fourteen in the American League, allowing five teams in each league’s playoff means there are fewer rotten seeds in the garden. That’s what you call “growing” a postseason audience.

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Merrill Perlman managed copy desks across the newsroom at The New York Times, where she worked for 25 years. Follow her on Twitter at @meperl.