Probability of finding a four-leaf clover

Short answer: around 1 in 2,000.

(Clarification: this is the probability that, if you pick up a single leaf at random, it will have four leaflets.)

Here is my collection of four four-leaf clovers (out of five, the fifth has shredded leaves), collected over a period of two weeks.

If you look at the wikipedia page (& refs therein), the most commonly cited figure is 1 in 10,000. Unfortunately there are no actual observations reported anywhere.

But now I can report that, according to my very empirical research, the probability of finding a four-leaf clover is probably more like 1 in 2,000.

How do I know?

1. I find that I can scan around 100 plants per minute.
2. Most recently, I found two four-leafs in about 30min worth of scanning.
3. This gives a rate of 1 in 1,500

The previous attempts have however been slightly longer, although I didn't time them as accurately. Also, the actual number of plants scanned per minute can vary due to wandering attention. So, I would think a more conservative estimate is ~1 in 2,000.

Of course, these are all in upstate NY, although not at a single location. Perhaps these rates vary with a whole bunch of other factors.

Still, these are fairly low odds - finding 5 four-leaf clovers, even with these better estimates, is still less than one in 10 quadrillion! (Clarification again: this is the probability that, if you pick five leafs blindly, all five will have four leaflets each.)