Best-kept secrets of your neighbor’s backyard part 3: Dogwood berries

Titles I abandoned:

-Dogwood Berries (surprisingly evocative of “dingleberries” as a standalone title, no? Maybe it still is as part of a longer title. Ah well.)

-Things you can eat on trees in Seattle (this would be a weak lead for such a series. Dogwoods grow plentifully elsewhere. Also, wouldn’t such a list obviously start with apples, followed by Rainier cherries?)

So anyway, hi, everybody! A year ago we moved to Seattle, and I started a lab in the Biochem department at UW. It’s been…honestly, pretty great. And I’m sure you will be shocked to learn that in an area that is famous for being damp and green, there are many green edible things that grow. So many berries, you guys. But all the native berries will have to wait their turn. The one that finally got me to take pictures for a post was this goofy looking thing I discovered in our back yard this afternoon:


Which had fallen out of our dogwood tree. When I looked up at it I saw more:


I have done frankly minimal research into what variety of dogwood is growing in our yard, and I haven’t yet seen it flower, which makes identification a little harder. But a quick perusal of the internet yielded consensus that, edibility-wise, dogwood berries range from “non poisonous” to “a sought-after delicacy,” and so I was sufficiently emboldened to give it a try.

Various users described the fruit as lychee-like, and to be sure the outside resembles a lychee both in its color and the dry, pebbly texture of the skin. There is no taxonomical affinity though: dogwoods come from the order Cornales, and are more closely related to hydrandgeas, lilacs, and olives than to lychees, which belong to the order Sapindales along with citrus, mangoes, and cashews. After cutting into the fruit, the inside is much softer than lychee, verging on mushy. Others described it as melon-like, which I think is much closer. Not only is the internal color a peachy orange rather like cantaloupe, but the flavor reminded me of a very ripe, soft honeydew. The skin itself is bitter, so I peeled it off and ate the just the soft inside portion. In my opinion, our home-grown dogwood berries are something I would very enthusiastically eat if I was hungry in the wilderness, and will happily eat when I find them in my own yard, but not something I’ll likely seek out in large numbers. They’re a bit too squashy and the outsides too much trouble to eat by the dozen. I’d be interested to hear the opinions of others; after all, ours might not be the “sought-after delicacy” subtype, and there might be more compellingly delicious dogwoods out there.



-there is a single, rock-hard seed in each berry. Don’t break your teeth!

-Apparently contact with dogwood leaves can cause skin irritation in some. Proceed with reasonable caution.


“P” is for poinsettia, pyracantha, and paucity of poisonousness

Happy New Year, everyone!

As you may have noticed, 2012 got a little bogged down toward the end, and poor Mendel was woefully neglected.  But, while I abhor resolutions, I have come into 2013 with new enthusiasm, and have been reminded that I’m actually quite fond of my little blog.  So, in the spirit of things that deserve another chance, here are two seasonal favorites you may have been judging unfairly for as long as you’ve known them.

1.  Poinsettia (Euphorbia pulcherrima)

I certainly was raised in the firm belief that poinsettias were basically a festive holiday deathtrap.  Which even as a child I found a bit baffling–“Here kids!  Eat all these holiday cookies and brightly colored candies and look at these gorgeous, enticing bright red flowers that we’ve put all over the house but OMG DON’T TOUCH THEM THEY’LL KILL YOU!”!  Not poisonous after all you say?  Just nauseating and irritant?  Fantastic!

Looks…so…tasty…must…not…eat…Oh! Not poisonous after all you say? Just nauseating and mildly irritant? Fantastic! (Photo by Scott Bauer, via Wikimedia)

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Steel magnolias: using magnolol to combat arthritis

The gorgeous display of magnolia flowers around campus has been capturing my attention over the last few weeks, but it turns out they’re just as noteworthy for their therapeutic potential as for their aesthetics. A new article in press for PLoS One (open access for everyone!) describes a novel activity for the Magnolia officinalis derivative magnolol in repressing inflammation, which is a pretty tantalizing topic for a runner like me who’s always a little bit neurotic about the health of her joints.

Flowers of Magnolia x soulangiana, a cross between M. lilliflora and M. deundata.

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Magnolia x soulangiana

The pink magnolia tree on the street outside our house has been cropped into a rather unfortunate blocky shape in an effort to keep it from obstructing the sidewalk.  Nevertheless, the buds it produces  this time of year are awfully pretty.  The mix of fuzzy, smooth, and knobbly textures on the sepals, petals, and twigs always makes me want to grab a pencil, so…

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Prettiest Plant in the Lab: Foxgloves, Digoxin, and Digoxigenin

A while ago I posted about oleander and the structural similarities between the oleander cardiac glycoside oleandrin and the foxglove cardiac glycoside digoxin.   But foxgloves express enough biologically useful (and harmful) molecules that they’re worth showcasing.  Plus they’re such nice eye-candy!

Gloves that pack a punch

The various members of the Digitalis genus, which include the gardener’s favorite foxglove Digitalis purpurea and a range of other Digitalis species, are favored ornamental plants for their tall showy flower spikes and bright colors.  A disputed but appealing origin for the name was advanced by William Henry Fox Talbot, who proposed that the whimsical ye Olde English people imagined fairies wearing the deep cone-shaped flowers for gloves, and called them folks’ gloves.  Very cute.  But given that fairies were famous not only for being adorable but also for other light-hearted mischiefs like stealing babies and poisoning livestock, it’s perhaps fitting that their pleasing-to-look-at gloves come barbed with a heavy dose of serious poison.

Enough folk's gloves for a children's book full of fairies. Digitalis purpurea, by Ferdinand Bauer.

Foxgloves are poisonous because they contain two cardiac glycosides, digoxin and digitoxin, which are found in all parts of the foxglove plant but are most concentrated in the leaves.  There are a few ways to poison yourself with foxgloves by mistake: the flowers have some appealing similarities to honeysuckle, which might lead the unwary to try to suck nectar from them.  Because the plant is still poisonous when dry, a hapless gardener might inadvertently inhale foxglove plant matter when digging or replanting near an old foxglove bed.  The leaves of foxglove (especially before it flowers) resemble and have sometimes been mistaken for comfrey, which is benign and a common basis for tea (here’s an article about several people poisoned this way).  Never fear though, ehow has a handy how-to on distinguishing comfrey from foxglove leaves; the clearest difference might be that foxglove leaves are finely toothed while comfrey’s are smooth.

Leaf of comfrey, Symphytum sps. Good for tea, beloved by herbalists, and pretty easy to confuse with foxglove leaves, pictured in the illustration above. Photo courtesy of Heather at, which is also a pretty nifty blog.

Finally, one of the side effects of digitalis poisoning is strong hallucinations, so there may be a handful of people out there ingesting it deliberately…but I doubt the visuals are worth the heart arrhythmias, severe nausea, fainting, coma and possible death that come with them.

Extra nitty-gritty: Digoxin as heart medicine

Cardiac glycosides like digoxin and oleandrin work as sodium-potassium ATPase inhibitors, which means that they interfere with the balance of ions inside cells. The muscle cells of the heart are particularly vulnerable to changes in sodium concentration, because sodium concentration is coupled to calcium export, and the calcium concentration inside the muscle cell is what regulates how strongly or quickly the muscle cell can contract.  When there’s too much sodium, the cell can’t efficiently export calcium, and the cell contracts too strongly as a result.  Erratic muscle contractions are certainly bad news for a healthy heart.

Digoxin: sometimes a help and sometimes a hindrance to heart function.

Unlike oleandrin however, digoxin has considerable utility as a medicine: the same calcium ion hoarding effect that’s so dangerous in a healthy person can be used to combat heart failure by promoting stronger contractions in a damaged heart, and digoxin gained FDA approval as a treatment for chronic heart failure and some kinds of heart arrythmias in 1998.

The initial use of digoxin came before beta-blockers were used to manage heart failure (HF), and there is ongoing study as to whether digoxin remains valuable as an HF management strategy in concert with other therapies. A recent article in the International Journal of Cardiology has undertaken a multivariable regression approach to attempt to classify which categories of patients are more likely to suffer higher mortality or further hospitalizations for heart failure following digoxin use.  Their meta-study combined cases of over 7000 patients, and found that higher mortality and hospitalizations for heart failure were correlated with groups of patients that were female and had high blood pressure.  Studies like this one may help identify which groups of patients can still benefit from digoxin and which groups should avoid it.

Extra nitty-gritty II: Digoxigenin as molecular label

Apart from its cardiac glycosides, Digitalis also harbors a supremely handy steroid, Digoxigenin (DIG), which I use routinely to label RNA molecules.  Digoxigenin is a fairly small little molecule that can be coupled to the nucleotides that make up DNA or RNA (nucleotides=letters: A,G,T/U, and C), and there are specific antibodies for DIG that can be used to detect it anywhere it’s bound in a cell.

DIG-UTP. This labeled "U" is incorporated into RNA molecules just like regular UTP.

So when I want to find which cells in my tissue sample are making a certain RNA, I can make a probe with a complementary sequence and some of the U’s labeled with DIG.  Then I can use anti-DIG antibodies (conjugated to an enzyme that makes a purple color under the right conditions) to look for the probe, with a technique called in situ hybridization.

A little how-to for using DIG-labeled UTP to find a target RNA by in situ hybridization.

Want more details?  Here are references for the articles mentioned:

Ather S, Peterson LE, Divakaran VG, Deswal A, Ramasubbu K, Giorgberidze I, Blaustein A, Wehrens XH, Mann DL, & Bozkurt B (2011). Digoxin treatment in heart failure – unveiling risk by cluster analysis of DIG data. International journal of cardiology, 150 (3), 264-9 PMID: 20471706
Lin, C., Yang, C., Phua, D., Deng, J., & Lu, L. (2010). An Outbreak of Foxglove Leaf Poisoning Journal of the Chinese Medical Association, 73 (2), 97-100 DOI: 10.1016/S1726-4901(10)70009-5

Roadside edibles: missed one!

As I was jogging through the Berkeley marina yesterday, I realized I left a roadside edible out of last week’s post!  How could I forget the bright and peppery nasturtium?  It’s pretty much everyone’s favorite edible flower, an easy garnish to dress up your salad.

Tropaeolum majus, or Nasturtium to its friends. I found this one at the Berkeley marina near the parking lot of the Doubletree hotel.

The leaves are good too, but quite spicy.  I just learned that the flowers I know as nasturtium are from Tropaeolum genus (this one is most likely T. majus), but are named for the Nasturtium genus that includes watercress, because they produce a similar peppery-flavored oil.

Nasturtiums are native to Central and South America, but grow easily here. They’re popular not just because they’re pretty and hardy, but also because they deter many types of insect pest, and can act as a “trap crop” for pests (specifically aphids) that would have a more devastating effect on other crops.  Pretty and selfless!

Oleander: backyard killer has a softer side?

A murderer lurks in your neighborhood.  It’s Nerium oleander, and it’s everywhere. Great swaths of it envelop LA freeways.  It’s littered across backyards, and encircles parking lots.  And it’s deadly poisonous to humans, animals and especially kids so don’t taste it, don’t sniff it, don’t even touch it, OMG I brushed against it AAAHHHH!!!

Don't be fooled by the sweet pink exterior. It's totally out to get you. (Photo by Servophbabu, Creative commons attribution 3.0 unported license)

Actually, it may not be quite that big a deal.  Although all parts of the oleander plant are toxic, and quite a lot of people are treated for oleander poisoning in the US, there have actually been only a handful of adult deaths from oleander poisoning in the last 25 years.  Most of these were deliberate self-poisonings, with the exception of a young couple of vegans who got lost while hiking and ate a whole mess of oleander leaves.  Estimates I’ve seen suggest that a lethal dose to a child would be about one whole leaf, and several leaves for an adult, and the potential for poisoning by skin contact is minimal.  So, while you should definitely watch out for your kids around oleander, you don’t have to be quite as afraid of it as I always thought. The urban legend about a troop of boy scouts who died after roasting their marshmallows on oleander sticks, for example, is almost certainly bunk.

That having been said, getting sick from incidental leaf consumption would be no fun, and oleander really is everywhere, so here’s what to look for:  it’s a tall shrub, 2-6m high, often used in neighborhood hedges.  If you live anywhere in southern California (or some places in northern California, like along the 80 between Davis and Sacramento), you’ve seen it lining the freeways and medians.

A menacing stretch of median oleanders. (Photo borrowed from, but original photographer unknown).

The flowers are vibrantly pink or red or sometimes white, and grow in bunches.  Most distinctive are the leaves, which are dark green and leathery, and shaped like thin daggers about 4-8 inches long (there’s that assassin imagery again).  The leaves and flowers are poisonous because of several compounds, but notably the cardiac glycoside oleandrin/oleandrine and its metabolites.  Cardiac glycosides interfere with the Na+/K+ ATPase pump in heart muscle cells, throwing off the balance of ions inside the cell, and ultimately leading to it contracting faster and more strongly than it’s supposed to.  So oleander poisoning can result in irregular heartbeat, poor circulation, seizures, coma, and death.

Oleandrin. My heart's all a-flutter just looking at it.

Myth busting

While I was in college near LA, I encountered a rumor that oleanders were heavily planted along the local freeways because they were able to metabolize carbon monoxide (CO) emissions from cars, thus cleaning the air.  Turns out, the rumor may have had it exactly backwards.  A whole litany of plants, maybe all of them, can take up and metabolize small amounts of CO from the air—this was determined by Canadian botanists Bidwell and Fraser in the 1970s, who put radioactive C14-labeled CO into the air around plant samples, and recovered the C14 label from the plant later.  But the only study that talks specifically about oleander and CO is by Fischer and Luttge in 1978, who found that oleander was actually a net producer of CO through C1 metabolism of glucose.  That is to say, they might take up a little CO from the air, but then they actually make more of it in their own metabolism.  So no air-quality help there.

Extra Nitty-Gritty: Plant crossover!

One of the treatments for oleander poisoning is a digoxin immune fab, using antibodies raised against a similar glycoside from the plant foxglove called digoxin.  Apparently, oleandrin and digoxin are similar enough that antibodies raised to the latter will also bind the former.  The antibodies work by binding to the glycoside and preventing it from reaching its target in the body and causing harm–it’s the same principle used to make snake or spider antivenom.

Oleandrin and digoxin. You can see how the pink-highlighted parts are almost identical, so that some antibodies that are made to bind to digoxin will also bind the corresponding parts of oleandrin.

Anything oleander is good for?

In previous centuries, oleander was used as an herbal medicine to treat everything from headaches to eczema, which makes me queasy to think about.  Since digoxin is used therapeutically for some heart conditions, I thought oleandrin might be the same, but its therapeutic index seems pretty limited in that context.  However, it does appear that the same Na+/K+ ATPase pump interfering properties that make oleandrin so dangerous to heart cells also make it effective at killing off some kinds of cancer cells when used in concert with chemo- or radiotherapies.  But a drug based on oleandrin called Anvirzel stalled after Phase I clinical trials in Ireland (due to poor performance–no reduction in solid tumors was seen but side effects were, and at least one company trying to inflate claims of its efficacy and continue to sell it got in serious trouble with the FDA). Now it’s the subject of an alarming cancer home-remedy fad based on making oleander extract at home.  People, please don’t poison yourselves!

Want more detail?  Here are the references:

Fab antibody fragments: some applications in clinical toxicology.  Flanagan RJ, Jones AL. Drug Saf. 2004;27(14):1115-33.

Cardiac glycosides in cancer research and cancer therapy. Winnicka K, Bielawski K, Bielawska A. Acta Pol Pharm. 2006 Mar-Apr;63(2):109-15.

Phase 1 trial of Anvirzel in patients with refractory solid tumors.  Mekhail T, Kaur H, Ganapathi R, Budd GT, Elson P, Bukowski RM. Invest New Drugs. 2006 Sep;24(5):423-7.