Plant Story -- Strawberries. Fragaria, Beloved Fruits 1. Distribution and Botany

Strawberries, genus Fragaria in the rose family, Rosaceae, are a popular fruit and have been for millennia. Twenty to 24 species are recognized, with cultivated strawberries adding many hybrids and varieties. They are native around the world, mainly in the northern part of the Northern Hemisphere, plus a few Southern Hemisphere species.

strawberries, Fragaria

The Flora of North America says the name Fragaria comes from fraga, Latin for fragrance, and -aria, possession, so, a sweet-smelling fruit. Other explanations exist; for example Wikipedia says fragum is strawberry in Latin and -aria makes it a feminine plant name. My Latin dictionary agrees that fragum is the word the Romans used for strawberry but says fragrans is Latin for fragrant. In Latin declensions, fraga is the plural of fragum, in which case fraga means strawberries rather than fragrant. However, some of forms of the noun add an r, for example fragris and fragra, so would have sounded a lot like "fragrant" to Romans, which could explain the otherwise mysterious choice of fraga for strawberry. (Linguists always want to see why people chose this name and not some other one.) Linnaeus created the scientific name in the 1750s, adding -aria, likely making it "of strawberries" to refer to the whole genus not a particular strawberry. 

wild strawberry

The common name strawberry is obscure too. The name goes back to Old English and is not reflected in other Germanic languages, for example German says die Erdbeere, earth berry. An easy answer is that the English grew strawberries mulched in straw. The objection to the straw explanation is that strawberries were undoubtedly gathered long before anyone cultivated them and the use of the name strawberry is very old. The Oxford English Dictionary says that straw could refer to the seeds (achenes) of the strawberry dotting the surface of the fruit, since one of the meanings of straw is "a particle of straw or chaff, a mote." Alternately the OED points to another meaning of straw, for stalks of plants so people said "pea straw" and "poppy straw," so the straw of strawberry could be its runners, a distinctive character if you are out gathering strawberries. 

Strawberries are odd fruits, the tasty flesh on the inside and the seeds across the surface. They are familiar, so we rarely notice that they are inside out compared to a cherry or a watermelon. This is why strawberries are not berries to botanists. Botanists laid out as many fruits as they could find (a lot!) and made categories based on structure. They defined berry as fleshy fruits that develop from the plant's ovary with the seeds within. Since the seeds of the strawberry are on the outside, it was excluded. Those superficial strawberry seeds are actually one-seeded fruits, called achenes, the ovary that was around them in the flower now a single layer around the seed. As the fruit ripens, the structure that held the ovaries when they were in the flower, called the receptacle, expands, fills with sugars and turns red. Botanists say they are aggregate accessory fruits (not berries). But, as peering in any dictionary will show you, we use lots of words in many different senses. Strawberries have had berry on their name since long before botanists created their classification system.

Strawberries, Fragaria x ananassa

Across much of the world, you can find native strawberries. Different species in different places. All are herbs that spread by runners (stolons).  Strawberry flowers range from white through quite pink. In most species the leaves have three lobes, but a few species have five lobes. The fruits are usually red when ripe but sometimes quite pale. Some fruits taste very sweet but others are quite tart. In all cases, they are believed to be distributed by animals: animals eat the fruit, taking in the seeds, and disperse the seeds in their feces. Fruits turn red and become soft and tasty, from green, hard, and flavorless, when the seeds are fully ripe. (Trees that are called strawberry trees--there are several--have fruits that remind people of strawberries but they are not closely related to strawberries.)

unidentified strawberry 

The photo below is of a market in Stockholm, Sweden, selling strawberries (July 2, 2016). These were cultivatated. People were careful to tell me that the best strawberries would arrive in another week or so. Those were wild strawberries, carefully gathered from Sweden's forests. Strawberries vary.

The genus Fragaria, all of them called strawberry, is famously polyploid. The wood or woodland strawberry, Fragaria vesca, native all over North America, is diploid (2n = 14), as are a number of other species. But, chromosome counts of other species found tetraploid (4x) species, such as Fragaria orientalis. Other species proved to be hexaploids (6x) as Fragaria moschata, widely cultivated in Europe. And then there were octoploids (8x) like the common or Virginia strawberry Fragaria virginiana, native all over North America, and decaploids (10x) as the Cascade strawberery, Fragaria cascadensis, first described in 2012, and found only on the western slopes of the Cascade Mountains in Oregon. In general, leaves, flowers and fruit are bigger in the higher polyploids of strawberries. Our cultivated strawberry is not found in the wild. Two strawberry species crossed in cultivation in Europe some 200 years ago to create it. Those two strawberries, Fragaria virginiana and Fragaria chiloensis are both octoploid (8x) species, We recognize the hybrid as Fragaria x ananassa, a named hybrid (the x means hybrid) and it has really big fruits. See photo above with penny for scale. Fragaria as a whole is a classical example of a genus where many species formed by hybridization followed by polyploidy (whole genome duplication). (See previous blog link).

woodland strawberry, Fragaria vesca

Strawberries live in a variety of habitats. In some of those habitats, germination from seeds is easy, in other places bad weather often kills seedlings. Strawberries mitigate this not only by being perennial, so they can drop seeds again next year, but also by vegetative reproduction. They spread along stolons, horizontal stems, that put down roots having crossed the rocks or found a patch of sunlight in the forest. 

Thus, strawberries can form large patches even if pollination is poor or seedling survival chancy. 

This is a very successful genus. Not only is its natural distribution all across North America and Eurasia and down the Andes into South America, but humans have made strawberries one of the biggest commmercial crops so it is cultivated in even more places. The fruit and and its taste are familiar to and liked by millions of people. 

Comments and corrections welcome

NOTE: This got long. I'll talk about uses and folklore in an upcoming post. 

References

Liston, A., R. Cronin, and T.-L. Ashman. 2014. Fragaria: A genus with deep historical roots and ripe for evolutionary and ecological insightss. American Journal of Botany 101: 1686-1699. link

Oxford English Dictionary, s.v. “straw (n.1),” March 2024, https://doi.org/10.1093/OED/7646869728.

Oxford English Dictionary, s.v. “strawberry (n.),”  March 2024, https://doi.org/10.1093/OED/1031267711.

Staudt, G. 2020. Fragaria. Flora of North America. link

Kathy Keeler

A Wandering Botanist

More at awanderingbotanist.com

Join me on Facebook: https://www.facebook.com/AWanderingBotanist