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Oh-my-laria! The Equinox to Solstice plant- Oemleria cerasiformis

Oemleria cerastiformis flower, oso berry, june plum, indian plum

As the summer solstice passes, a very 'spring to summer' plant comes to mind- oso berry. They are pretty much the very first native plant to bloom in our area, a PNW herold to spring. And around the summer solstice is when their oso-dangly fruits ripen. Previously known still as "Indian plum", the progress of renaming plants to remove the colonial offensiveness is in favor of oso berry. “June plum” is better too and helping highlight the deep purple berries.They are a native plant familiar to many of the PNW tribes and oso berry better represents them. I love the genus name- Oemleria- and often think of them as just that. Oemleria cerasiformis is the full species nomenclature.

Oemleria is named in honor of the Dresden friend of the German botanist Reichenbach, a Herr Oemler. This pal was in the Americas and sent many new species over to Germany. It is an extra special genus because it only has 1 species categorized within it, called a monotypic genus as it has 1 (mono) type. They are in the rose family- Rosaceae.

oemleria flower, osoberry, oso berry, oemleria cerasiformis

Oso berry (also spelled as osoberry) plants are small slender deciduous shrubs, about 10-20’ (4-6m) tall with slim branches and often an open random pattern, giving them a slight delicate feel along with their large thin oval leaves. Deer are fond of browsing them, so I expect they are ‘cheap’ for the plant, meaning thin with little defenses like chemicals or spines, hairs, etc. They are a “utility leaf” (as some plant nerds have termed your basic functioning traits), just spring forth from the shoot tips in early spring growing fast and cheap without any frills just to photosynthesis and build up sugar stores for next spring’s big bloom. A few deer nibbles are fine, they’re resilient. Who can blame deer anyway- the new leaves have a cucumber taste, must be refreshing after they denude your rose bushes and columbines, right?

Delicious salad idea- young soft mahonia leaves plus a few sliced oso berry leaves = lemony cucumber salad. Mmm.

Watch how the flowers developed (shown in reverse order) with a photo taken roughly every day for weeks.

The real fun part of oso berry is partly from the name- the berries. Well, drupes with a single seed, not actually a true berry, so they are a bit misnamed. Oso drupe, or oso cherry would have been more accurate, and the June plum is actually pretty good.

oemleria cplums- by Leslie Seaton

They do make edible small plum purple fruits in drooping clusters like an ovoid cherry, which is also the species name’s meaning “cerasi”/cherry “formis”/shaped. But before you get fruit in early summer, you see the uniquely monosexual white star-shaped and hanging Oemleria cerasiformis flowers on a tight racemes.

oemleria flowers, oso berry flower, june plum flowers, oemleria cerasiformis bloom

The plants are dioecious with only male or female flowers on one plant (dioecious means “two houses”) and annoyingly there are WAY more male oso berries than female. Osos be making more twigs than berries, if ya know what I mean. Between these oso-bros and the all male trailing blackberries around my place, it’s a plant-based sausage fest. Where my lady-plants at?? It’s much less reproductively advantageous to have only a few males to pollinate many females, so….? What’s up with this well known lean toward these native all-male plants? Oemleria do create small groups asexually via suckering. I feel like the males sucker more, but I could be just projecting. The sexes are called genets (fyi). Yay botany scrabble!

dioecious flowers, male genet, male flower, male flower genet, oemleria male flower, oemleria flowers, male oso berry, male osoberry flowers
male oemleria flowers (male genets)

Some research has shown that male dioecious plants grow faster than female genets, assumed because the females take more resources to make their fruits. Eggs, ovaries, seeds, and fruit are all more expensive for resources from a plant than pollen and… well that’s about all the male flowers do differently from females.

female Oemleria flower, oemleria cerasiformis flower, osoberry flower, female flower
Female Oemleria flower with big green ovaries. Vestigial non-functional stamen are visible as well.

In biology, males are cheaper (don’t we know it!) and can be faster at growing and also more expendable. Sorry guys, but interesting biology truths can sting. Research also indicates mortality rate is higher in the females, so during stressful growing periods, we are likely seeing more die-off of the female genets, which is a concerning trend.

dioecious flowers, male genet, male flower, male flower genet, oemleria male flower, oemleria flowers, male oso berry, male osoberry flowers
more dudes hanging around my area

In fact, across 60 studying populations of Oemleria cerasiformis in the western US, 56 of them were male-heavy. The male genets also bloomed earlier, probably able to change their phenology easier with earlier warming springs than the females. Anyone out there intentionally planting more female plants to keep this lovely species from disappearing?

Now I wonder if deer find either sex tastier? Whose more cucumber-y?
female osoberry, female oso berry, female flower, female genet, oemleria cerasiformis female flower, female oemleria
She's a lady! Woh oh oh, she's a lady

Once the rare oso lady berry gets pollinated, the stinky males begin to fade. Apparently the flowers are though to be stinky once plucked so they make poor flower arrangements but I

haven’t noticed. The flowers form the namesake fruits over several months, first going from green to yellow to red to purple and very bitter when not fully ripe which are then actually pretty tasty but some report they are bitter even when fully ripe, that is if you can find where the ladies are hanging out and catch a ripe berry before the birds do.

I do wonder if their drupe fruits are like an avocado where you have about 1 day to catch it at actually ripeness. Oh, don’t eat the seeds though. They contain the same cyanoglucosides that almonds and other almond-smelliong plants have (cherry and laurel leaves for example) and are toxic, which is why we blanch our almonds- to remove that toxin.

TLDR?: too long didn't read

You can find these lovely dainty shrubs throughout the western most US in open forest patches and edges as well as streams. Enjoy the big bright green leaves while you look for some droopy purple drupes on the precious female genet and count yourself very lucky. Soon they will yellow and loose those leaves in the higher heat and drought of late summer as they prepare for winter’s long slumber. And then, as a harbinger of hope, they will pop those dioecious flower clusters out at the first sign of spring and weeks before their leaves, to start all over again.

june plums, oso berries, osoberry, oemleria fruit, oemleria drupes
early ripening oso berries

I’m going to go look for some ladies to take cuttings of and spread in my little woods. Because I believe in genet equality!


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