Difference Between Irish Shamrocks and Four-Leaf Clovers

History Draws Clear Distinction Between the Two

Red clover's tripartite leaf.
David Beaulieu

The thought of Irish shamrocks evokes visions of the green landscape of the Emerald Isle as surely as does Saint Patrick's Day, itself. But if you're seeking the real McCoy, you'd better start looking for some four-leaf clovers, because you'll need lots of luck: There is no authoritative version. Ironically, there's also a big difference between shamrocks and four-leaf clovers, for reasons that history makes clear.

"Shamrock" a Nebulous Term

The term, "shamrock," comes from the Irish word, seamrog, which translates as "little clover." That's rather vague, considering that there are many kinds of clovers (and even more plants that often pass as clovers). Consequently, in Saint Patrick's Day celebrations a number of plants serve as Irish shamrocks. 

Even among the Irish, there is no consensus that dubs one particular group of plants as the true Irish shamrocks, botanically speaking, as was reported in a 1988 survey. The survey, conducted at the National Botanic Gardens, Glasnevin, Dublin, revealed that when the Irish wear the "shamrock," it can be any one of four plants. Three of the plants are clovers, while the fourth is a clover-like plant known as "medick." All four are in the pea family:

  • Lesser trefoil, or hop clover (Trifolium dubium): 46%
  • White clover (Trifolium repens): 35%
  • Black medick (Medicago lupulina): 7%
  • Red clover (Trifolium pratense): 4%

Various members of the Oxalis genus, such as the so-called "black shamrocks" (Oxalis regnellii) and the wood sorrels (for example, Oxalis acetosella) are also sold as shamrocks for Saint Patrick's Day. These clover look-alikes are more easily cultivated as houseplants than real clover, making them popular as indoor decorations for Saint Patrick's Day. Despite their use as shamrocks, the wood sorrels, etc. are not even related to Trifolium.

Four-Leaf Clovers vs. Shamrocks

What medick, the wood sorrels, and the true clovers all have in common is a leaf made up of three leaflets. The number three is significant in the Christian religion because of the doctrine of the Trinity. Irish legend has it that the missionary, Saint Patrick, demonstrated the principle behind the Trinity using a shamrock, pointing to its three leaflets united by a common stalk. But there is no way of determining with certainty the exact plant referred to in the legend.

This much we can say about Irish shamrocks, however: By definition, for a clover to represent the Trinity, it would have to bear three (and only three) leaves. So for all of the good luck they allegedly bring, four-leaf clovers technically can't be considered shamrocks (not in the sense in which Saint Patrick made the latter famous, at least).

It was the priests of the ancient Celts, called "Druids," who elevated four-leaf clovers to the status of good luck charms, potent against evil spirits. This is the origin of the modern belief in their power to bring good luck.

For the most part, the four-leaf clover is not a separate species, just a freak of nature. That's why people feel so lucky when they stumble across one. If you want to "make your own luck" and don't mind going outside the Trifolium genus, buy an Oxalis deppei plant. Oxalis deppei is widely sold as the "good-luck plant," because it bears a leaf that always has four leaflets.

Clover Beneficial to Lawns

Considering the Saint Patrick's Day traditions surrounding shamrocks and four-leaf clovers, it is surprising that the clover is often looked upon as merely a common lawn weed, the killing of which we deem central to lawn care. But it was not always so. Indeed, the University of Minnesota Extension Service points out that, until relatively recently, it was standard practice to include clover seed in lawn seed mixes:

"Until the 1950s, clover was included in lawn seed mixes as it was regarded as a prestigious lawn plant. It may be considered an attractive, low-maintenance ground cover that is soft to walk on, mows well and will fill in thin spots in a yard."

The grass lawn is practically an institution for those who expect to find a space composed solely of green grass in front of a suburban home. In their opinion, anything else growing in the space is harmful (a "weed").

But clover is beneficial to lawns. Moreover, it goes largely unquestioned that grass will serve as your "carpeting" for outdoor living. But perhaps it is time to ask some basic questions about lawn care and the landscaping needs in front of a house.

Imagine yourself opening your front door and stepping out onto your ideal landscape. Here are some of the components it would probably have:

But now we come to the "carpeting" for your outdoor living space. For you will need to fill in between your bedding areas and trees and focal point with something that you can walk on. While mulches and hardscape paths adequately fill this role for some people's tastes, other folks like the feel of something live under their feet. Here are the qualities the ideal living carpet of green would have:

  • It stays a luscious green all summer, but it's drought-tolerant enough that you don't have to water it constantly.
  • It out-competes weeds fairly well, thus reducing the need to apply herbicides. Your carpet competes so well for growing space that the competition is choked out.
  • It doesn't need to be fertilized.
  • It is also relatively free of damage from insect pests so that you do not have to bother spraying pesticides on it.
  • It aerates the soil on its own so that you don't have to worry about counteracting soil compaction.
  • It is soft to walk on.
  • It attracts beneficial insects, including honeybees.
  • It rarely has to be mowed.
  • It doesn't suffer the discoloration from dog urine known as "dog spots."
  • If you should ever want to replace it with a different kind of green carpet, it helps you to do so by improving the soil on its watch. Its ability to aerate the soil and pump nitrogen into it means that succeeding generations of plants using that soil will be better off.

No grass has all of these qualities. The ideal qualities on the list largely describe not a grass, but clover. So let's consider having clover replace grass as the living carpet of choice (even if only partially, in the form of a beneficial mix of grass and clover). 

Clovers Lawns vs. Grass

The reason clover lawns don't require fertilizing, as does grass, is that these plants are nitrogen fixers. They share this ability with other cover crops in the pea family.

Clover snatches nitrogen out of the air, bringing this essential fertilizer down to earth by means of nitrogen-fixing bacteria living in nodes along the roots (all at no cost to you, in terms either of money or of maintenance).

You may also be wondering about clover's ability to aerate the soil, thus reducing concerns over soil compaction. Clover tolerates compacted soil better than lawn grass does. It has longer roots, enabling it to access water at deeper levels.

Finally, a word about two of clover's other ideal qualities: its ability to attract honeybees, and the fact that clover lawns usually don't need to be mowed as often as do lawns composed of grass:

  • Clover puts out a mildly attractive flower, which could easily be listed as another advantage it has over grass. This flower draws bees and other beneficial insects to your landscape.
  • But if you are allergic to bee stings, to be on the safe side you can simply mow more frequently during the blooming season. If you are not allergic to honeybees, this should not be a concern; for honeybees tend not to be aggressive away from the hive anyway. If bees are not an issue, you won't have to mow as frequently with clover as with grass.

The Movement Against Lawn Grass

But it's not a matter of all or nothing, and one advantage grass does have over a clover lawn is that it stands up better to heavy foot-traffic. Mixing clover and grass together in the same lawn may provide the best answer for most people. But there is a growing movement in the U.S. to cut back on the amount of landscape consumed by lawn grass. Less.Lawn.com is devoted entirely to the movement against lawn grass. The steam that powers the movement against lawn grass comes from a number of sources, including:

  • Concerns over the excessive use of irrigation, which is why more people are turning to xeriscaping. Homeowners are tired of seeing their lawns die every summer or of paying through the nose to prolong a lawn's life
  • Concerns about the pollution caused by herbicides, pesticides, chemical fertilizers, and the emissions from lawn mowers
  • A desire for low-maintenance landscaping, as well as cheap alternatives to lawn grass. Mowing lawns, and applying herbicides, pesticides, and fertilizers to them, means more than just pollution. All of this costs money and causes you work, as does the need to aerate and irrigate lawn grass.

Having a clover lawn provides a solution to most of these problems. It is good for the environment, and it saves you money and labor. Experiment in a small area of your yard with a clover such as Miniclover (a type of white clover) to see if a clover lawn is right for you.