Among the earliest gardeners in America are the Irish who traditionally plant potatoes on St. Patrick’s Day, often in the cold and blowing wind. Many Americans know that the failure of the potato crop caused an exodus of Irish natives to the United States. The subsequent contributions of the Irish Americans and their descendents range from politics to law to nearly every type of art and industry. But few are familiar with the Irish people’s profound impact on the potato.

Solanum tuberosum originated in the northern Andes, having been a staple food there for thousands of years, based on a diverse and multicolored crop cultivated extensively by the Inca when Francisco Pizarro arrived in 1532. As today, it thrived in the elevated regions of the subtropics, not unlike a cool summer in Canada.

Europeans were slow to take up the potato. They suspected root crops to be less worthy than aboveground herbaceous vegetables and grains. Oddly, while these medieval superstitions were widely shared among commoners, French and Italian aristocrats treasured the “earth truffle” and “apple of gold” as a delicacy, and court ladies famously wore tiaras of potato blossoms in their hair.

However, the Spanish saw an ideal slave food in the compact, long-lasting and nutritious tubers, one of which would suffice a native miner for an entire day. Colonial British spies noted its efficiency as well as productivity and took the news, and probably tubers as well, back to England.

Before America, Ireland had become Britain’s first true colony. The spud was reckoned to be an ideal crop for the virtual slave population that made up the Irish peasantry. Cheaper to grow and prepare than grain and suited to cool, cloudy summers, the potato was introduced in County Wicklow about 1640. In a few decades the large, lumpy type became the dominant food crop, especially in the populous south.

The adoption of the potato in Ireland set the stage for one of history’s greatest and most tragic ironies. The British generally ignored one of nature’s perfect foods, maintaining instead a poor diet of processed grains, such as flour, and aged meats. On the other hand, fresh and earthy potatoes provided the Irish peasant family with excellent nutrition for over 200 years, until the first of several steadily worsening potato famines beginning in 1830. As a result, Ireland’s rural and impoverished population sky-rocketed from 4 million people in 1780 to more than 8 million in 1841. A diet of potato and dairy products improved Irish health to such an extent that, eventually, Ireland literally dwarfed England. The sturdy Celts became the “Irish giants” of fact as well as fiction. Not only were individual size and strength improved, but also infant mortality was dramatically reduced. Families typically had 6 to 10 surviving children.

Tragedy stuck when a voracious strain of the fungus, Phytophthora infestans, originating in a remote valley in Mexico and causing a disease called blight, escaped and spread throughout Western Europe in 1845. Its prodigiously infectious spores rode the moist winds during the unusually cool, overcast summers of 1846 and 1847. Since many of the several dozen potato cultivars used in this time were related, the fungus devastated the crops not only throughout Ireland, but also across Northern and Central Europe. For instance, Poland was only somewhat less hard hit than Ireland. But the land-locked Poles simply starved en masse, while the Irish had better chances to take to the seas.

In a great reversal of fortune, the potato’s god-sent qualities for Ireland disappeared in the Great Potato Famine, when starvation caused the death of over 1 million people by 1848, more than 12 percent of the population. Millions more immigrated to North America. Ireland had lost nearly half its people by 1900.

Growers and farmers immediately blamed themselves, the soil, the British—even Satan. However, the potato surprisingly rebounded quickly once Irish and British agriculturists found the remedy in new plant-breeding programs based on potatoes from fields that survived. Out of this laboratory of misery, tragedy begot triumph. Many historians consider the Great Potato Famine to have stimulated modern agricultural science, indirectly leading to such work as Mendel’s study of garden peas in the 1860s, which in turn led to the modern science of genetics, and the theory of evolution.

Certainly, the roots of western civilization were conserved by Irish monks, as Thomas Cahill described in his book, How the Irish Saved Civilization. But overlooked is the role the Irish played, and the sacrifices they made, in conserving one of the world’s greatest food crops. As we celebrate St. Patrick’s Day, let us remember the example of the potato’s history in Ireland.