A new strawberry species found right in our backyard

Elizabeth Case / The Oregonian /

In 1982, Ronald Reagan opened the World’s Fair in Tennessee, Michael Jackson released Thriller, and Otto Jahn, a researcher for the Agricultural Research Service, carried back a tiny strawberry plant from Hoodoo mountain in the upper Cascades.

Jahn curated a plant bank, the National Clonal Germplasm Repository in Corvallis, which is home to the national collections of strawberries, pears, blueberries and hops, to name a few. He planted it there, assuming it was a common wild strawberry, Fragaria virginiana.

Twenty-five years later, new research sweetened Jahn’s find.

That plant is the newest addition to the wild strawberry family, F. cascadensis. Kim Hummer, who took over the plant bank after Jahn retired, says the secret to the new strawberry species lies in its two extra sets of chromosomes, making it a rather uncommon strawberry after all.

The findings were highlighted in this month’s Agricultural Research magazine.

The first inklings of cascadensis’ unusual genetics emerged in 2007. Oregon State University doctorate student, Wambui Njuguna, and a geneticist at the repository, Nahla Bassil, were analyzing 24 plants to uncover a DNA sequence to differentiate strawberry species. During their research, a plant code-named Fra.110 kept returning more results than it was supposed to — a possible indication the plant had more chromosomes than assumed. Most native strawberries and commercial variations have two or eight sets of chromosomes. Fragaria virginiana, the plant Fra.110 was supposed to be, has eight.

Bassil and Njuguna sent the specimen to the Netherlands for further testing. The results confirmed their suspicions: Fra.110 wasn’t F. virginiana, but something altogether new. It had 10 sets of chromosomes.

“I got very excited. And I went to Kim and said ‘Listen everybody, let’s go collect,’ ” Bassil said.

Strawberry species can often be designated by their chromosomal number, said Aaron Liston, a professor of botany and plant pathology at OSU. Liston also works at the OSU Herbarium, which helped officially determine Hummer’s strawberry as a new species. The findings were first published last year in the Journal of Botanical Research Institute of Texas.

Since the confirmation, Hummer has collected 33 samples throughout the Cascades, after which she named the new strawberry. Cascadensis generally grows at elevations above 3,000 feet; virginiana only appears at lower elevations.

“I started by Burnt Lake, collected them there, collected them on Iron Mountain, Echo Mountain and going down to Waldo Lake and Diamond Lake, to Crater Lake,” she said.

She identified three traits visible to the human eye that set cascadensis apart. It has tiny white hairs on the topsides of its leaves, a uniquely shaped leaf and curved achenes — the tiny dried fruits on strawberry flesh often mistaken for seeds.

And while most locally cultivated strawberries ripen in June, the Cascade strawberry bears its fruit in August.

“My little strawberry is not the most flavorful, more acid than sugar,” Hummer said. Her favorite strawberry is the Holiday.