You may know everything about green beer and Irish stew, but if you really want to up your game this St. Patrick's Day, it's all about the shamrock.

Impress your Irish (and Irish-for-a-day) friends with this wide array of trivia about the tiny plant that brims with luck and a fascinating history.

1. First, you shouldn't use 'shamrock' and 'clover' interchangeably.

Especially if you're around some seriously Irish people. All shamrocks are clover, but not all clovers are shamrocks. Shamrock comes from the Gaelic word seamrog, which means "little clover," but no one — not even botanists —is sure which species of clover is the "real" shamrock. In 1988, botanist Charles Nelson did a shamrock survey for his book "Shamrock: Botany and History of an Irish Myth." The Trifolium dubium, or lesser trefoil, was the most common response.

2. You can grow clover indoors.

Many of the clover plants you see in stores are species of oxalis (wood sorrel) family, which are easier to grow indoors. The oxalis family has more than 300 species including Oxalis acetosella, also called the Irish shamrock, and Oxalis deppei, known as the good-luck plant. Shamrock plants need direct sun, barely moist soil and cooler temperatures.

four-leaf clover in a tiny vase3. A 'lucky clover' may be a mutant.

A four-leaf clover is a rare variation of a common three-leaf clover. Scientists are unsure if the cause for the variation is genetic, environmental, a mutation or all of the above. If the cause is environmental — like soil composition or pollution — that may be the reason one field may have several lucky clovers.

4. Your odds of getting lucky aren't great.

There are about 10,000 normal three-leaf clovers for every "lucky" four-leaf one.

5. The whole lucky clover thing was written about nearly 400 years ago.

The first known literary reference to clovers and luck was in 1620 when Sir John Melton wrote, "If a man walking in the fields finds any four-leaved grass, he shall in a small while after find some good thing."

6. The leaves in a lucky clover are symbolic.

According to Irish lore, the leaves of a four-leaf clover stand for faith, hope, love and luck.

stained glass window of Saint Patrick7. St. Patrick made the shamrock famous.

St. Patrick allegedly used the three-leaf clover to teach people about Christianity as he traveled around Ireland. He said the leaves illustrated the Father, Son and the Holy Spirit of the Holy Trinity.

8. Shamrocks are often part of Irish weddings.

For good luck, clover may be included in the bouquet of an Irish bride and the boutonniere of the groom.

9. Celtic priests were big believers in clovers.

According to Irish legend, the ancient Druids believed that carrying a three-leaf clover helped them see evil spirits so they would be able to escape them. They also used clovers to heal the sick and in religious rituals.

10. A clover can have a lot more than four leaves.

A 56-leaf clover was bred by Japanese farmer Shigeo Obara. ''I never dreamed of seeing this many leaves on a clover,'' said Shigeo, who placed decals on the leaves as he counted them to make sure his tally was correct.

11. There may be some biblical clover history.

Some biblical legends say Eve was carrying a four-leaf clover when she and Adam left Eden. She supposedly did so to remind herself of the wonderful paradise she was leaving behind.

12. Lucky clovers may help you see cool things.

In the Middle Ages, children believed that finding a four-leaf clover allowed them to see fairies. It was a popular pastime for youngsters to go out into the fields looking for the rare clovers; once they found one, they'd search for elusive fairies.

13. You're luckier if you don't go looking for luck.

A four-leaf clover is thought to especially bring luck to the finder if you stumble upon it by accident and aren't purposefully searching to find one.

bunny eating clover14. Cows, horses and other animals find clover quite tasty.

It's also nutritious because it's packed with protein, phosphorus and calcium.

15. The four-leaf clover is a well-known logo.

In the late 1890s and early 1900s, rural youth clubs were formed across the U.S. to give kids a better agricultural education. Early on, they used a three-leaf clover as their symbols with each leaf representing head, heart and hands. A fourth leaf was added and the club became known as 4-H. The fourth "H" momentarily stood for "hustle," but then was replaced with "health."

16. For a while, wearing a shamrock was illegal.

In the early 18th century, the shamrock became a symbol of Ireland and, by association, Irish nationalism and independence. Patriots started wearing the shamrock and the color green to show their support for nationalism. British authorities wanted to squash the rebellion and banned people from wearing the color green or shamrocks as a symbol of their Irish identity. Those who wore it were threatened with death.

17. Clover used to be eaten by the Irish, especially during times of famine.

The clover you find today in your lawn can be chopped up and added to salads. Even the flowers can be eaten raw or cooked.

Inset photos:

4-leaf clover: /Shutterstock

St. Patrick: Thomas Gunn/Wikimedia Commons

Bunny eating clover: Carly Lesser & Art Drauglis/flickr

Mary Jo DiLonardo Mary Jo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.