The History and Fascinating Botany of Cranberries

Sunday - November 26 2023, 21:14 UTC - 12 months ago

Cranberries have been a Thanksgiving staple in U.S. households for years, but they are surprisingly young agricultural crops and have many unique botanical features, such as hermaphroditic flowers and four air pockets that allow them to float and disperse their seeds. Native Americans in North America also used cranberries for foods like pemmican before they were domesticated.

Cranberries are a staple in U.S. households at Thanksgiving – but how did this bog dweller end up on holiday tables? Compared to many valuable plant species that were domesticated over thousands of years, cultivated cranberry (Vaccinium macrocarpon) is a young agricultural crop, just as the U.S. is a young country and Thanksgiving is a relatively new holiday. But as a plant scientist, I’ve learned much about cranberries’ ancestry from their botany and genomics.

New on the plant breeding scene .

Humans have cultivated sorghum for some 5,500 years, corn for around 8,700 years and cotton for about 5,000 years. In contrast, cranberries were domesticated around 200 years ago – but people were eating the berries before that.

Wild cranberries are native to North America. They were an important food source for Native Americans, who used them in puddings, sauces, breads and a high-protein portable food called pemmican – a carnivore’s version of an energy bar, made from a mixture of dried meat and rendered animal fat and sometimes studded with dried fruits. Some tribes still make pemmican today, and even market a commercial version.

Cranberry cultivation began in 1816 in Massachusetts, where Revolutionary War veteran Henry Hall found that covering cranberry bogs with sand fertilized the vines and retained water around their roots. From there, the fruit spread throughout the U.S. Northeast and Upper Midwest.

Today, Wisconsin produces roughly 60% of the U.S. cranberry harvest, followed by Massachusetts, Oregon and New Jersey. Cranberries also are grown in Canada, where they are a major fruit crop.

A flexible and adaptable plant .

Cranberries have many interesting botanical features. Like roses, lilies and daffodils, cranberry flowers are hermaphroditic, which means they contain both male and female parts. This allows them to self-pollinate instead of relying on birds, insects or other pollinators.

A cranberry blossom has four petals that peel back when the flower blooms. This exposes the anthers, which contain the plant’s pollen. The flower’s resemblance to the beak of a bird earned the cranberry its original name, the "craneberry." .

When cranberries don’t self-pollinate, they rely on bumblebees and honeybees to transport their pollen from flower to flower. They can also be propagated sexually, by planting seeds, or asexually, through rooting vine cuttings. This is important for growers because seed-based propagation allows for higher genetic diversity, which can translate to things like increased disease resistance or more pest tolerance.

Asexual reproduction is equally important, however. This method allows growers to create clones of varieties that perform very well in their bogs and grow even more of those high-performing types.

Every cranberry contains four air pockets, which is why they float when farmers flood bogs to harvest them. The air pockets also make raw cranberries bounce when they are dropped on a hard surface – a good indicator of whether they are fresh.

These pockets serve a biological role: They enable the berries to float down rivers and streams to disperse their seeds. Many other plants disperse their seeds this way, with the seeds traveling on the surface of rivers and eventually washing ashore and taking root in a new location.