It's that time of year in Los Angeles again, when the jacaranda trees are in full bloom, strewing their ultraviolet blue petals along sidewalks and roadways with wild abandon. I moved here from Washington, DC, known for its April cherry blossom festival, so it's nice to have a floral equivalent in my new hometown. Pasadena alone has some 3500 jacaranda trees, and they only bloom two months out of the year -- it's about as close as this region gets to bona fide "seasons," apart from the bit of rain that falls around January/February.
The Southern California variety are blue jacarandas (Jacaranda mimosifolia, which Jen-Luc Piquant things sounds like an exotic dance, a la the macarena -- or perhaps a designer cocktail at a chic hipster club). Apparently blue is a very unusual color to achieve in the botanical realm, according to a local horticulturalist, David Lofgren, who told the Los Angeles Times that our local trees actually originated in Argentina, Bolivia and Brazil (where the flowers are even bluer than the LA variety). But they can be found all over the world; in fact, the city of Praetoria, in South Africa, is known as the Jacaranda City because the trees are so prolific in that region. They tend to flower right around the time of student exams, which might explain the local legend that if a flower from a jacaranda tree falls on your head, you will pass your exams with flying colors. Hey, students need all the hope they can get.
Ironically, the superstition is reversed at the University of Queensland in Brisbane, Australia, where students say that they will fail an exam if a bloom from a jacaranda tree falls on their head -- unless they break the bad luck by catching another bloom before it hits the ground. Sydney University students are equally pessimistic: there, the saying goes, "By the time the jacaranda in the main quadrangle flowers, it's too late to start studying for exams."
Not everyone is a fan of the trees, despite their decorative value. That's because once they shed their flowers, it can get pretty messy, clogging drains, littering sidewalks, accumulating on the windshields of cars, and so forth.
The blooms are heavy because of the pods at their center, and can fall with a distinct thud. Step on a pod and crush it, and you'll get a sticky substance all over your shoe. Once that stuff dries, the only way to get it off is with something toxic like bug remover.
On the plus side, that juicy extract can be a very effective natural antimicrobial, particularly against E coli and Staphylococcus aureus. a.k.a., the "Golden Cluster Seed," or golden staph. It's a spherical bacterium that usually lurks on the skin or just inside the nostrils, and is the most common cause of staph infections. A plucky Scottish surgeon named Sir Alexander Ogston first discovered the staph "bug" in 1880; he found it in pus taken from surgical abscesses. It's still one of the most common causes of post-surgical wound infections. Some 500,000 patients in US hospitals get a staph infection every year.
Staph infections are nasty, causing everything from minor annoyances like skin infections, boils, carbuncles, and the occasional abscess (eww!), to more serious, life-threatening diseases like pneumonia, meningitis, endocarditis, and even toxic shock syndrome. They can usually be treated with a round of antibiotics -- unless one is unlucky enough to contract the "superbug", methicillin-resistant Staphylococcus aureus, or MRSA for short. For some reason, this particular strain quickly developed a resistance to most common antibiotics. And I mean quickly: Alexander Fleming accidentally discovered penicillin mold in a petri dish in the early 1940s; that petri dish was growing a staph culture. By 1950 40% of staph bugs in hospitals proved to be resistant to penicillin, and by 1960 the percentage had reached a whopping 80%. That's some pretty rapid evolution there.
It wasn't that big a deal until the 1990s, because MRSA infections remained fairly rare. Then there was an explosion of MRSA cases in hospitals, and it's been rampant ever since -- not just in hospitals, but in gyms and locker rooms as well. It's spread from human to human contact, and believe it or not, stringent hand-washing protocols actually make a big difference. In 2007, the BBC reported that MRSA infections could be held at bay by spraying vaporized essential oils into the atmosphere to fight airborne bacteria. And epidemiologists are struggling to develop mathematical models to better understand how such infections became so rampant after decades of being held tightly in control.
Jacaranda juice might have antimicrobial properties, but we're betting it's no match for MRSA. Still, the blooms are awfully pretty, which might explain why they've inspired so many artists and writers, not to mention local superstitions and celebratory street fairs. In his book, Chronicles of the Gray Angel, the Argentine writer Alejandro Dolina narrates the legend of a massive jacaranda tree planted in Plaza Flores in Buenos Aires, which supposedly whistled tango songs on demand. It's a fanciful notion, but while a jacaranda tree might not whistle a tango tune, it probably has a "voice" -- provided one knows how to listen.
Alex Metcalf is one man who's bothered to listen to the secret language of trees -- literally. I heard about his Tree Listening project via Geoff Manaugh's most excellent BLDGBLOG. Metcalf is a designer based in Cornwall who likes to explore the "natural world" in unusual interactive ways. His Tree Listening Installation is currently being exhibited at the Royal Botanic Gardens at Kew.
Basically, he's suspended nine sets of headphones from the branches of two of the largest trees: a Sessile oak tree, and a chestnut leaved oak. The headphones capture the sounds as water moves up through the Xylem tubes just behind the bark. At first, it sounds like thunder,or the revving of a motorbike, but listen a bit more closely and you might also hear a weird kind of clicking sound because the water mixes with pockets of air in the tubes. "This water movement is what keeps the tree alive by providing the leaves with the necessary water to turn into sugar as a source of food, and as part of the cooling system on a hot sunny day," he says on his Website describing the installation.
The headphones are so sensitive, they also pick up the sound of the trees vibrating with the wind. Metcalf didn't just go to Radio Shack and buy over-the-counter headphones, of course -- that would be lazy. He designed a special sensor to place on the trunk of a chosen tree, which is then linked to an amplifying unit. And it's all solar powered. To make sure the solar cells get enough "juice" from the sun, Metcalf places the components high in the tree canopy.
The best part about Metcalf's approach is that it's not the least bit harmful to the trees. As he explained to The Guardian, "The technology for this is usually invasive. You bore into the tree and take away a section, then seal in a listening device. The thing about my device is that you don't have to cause any damage, and you can listen to any tree, anywhere, any time." Perhaps even our local jacaranda trees have some secret thing to say.
First, a minor nitpick: Fleming discovered penicillin and its antibiotic properties in 1928, but was unable to develop a clinically useful preparation. The first patient successfully treated with penicillin was in 1942, using half of the entire US supply available at that time. In 1943, an optimal strain of Penicillium was found on a moldy cantaloupe in Peoria, Ill, and a method of large scale fermentation in corn-steep liquid was developed. By spring of 1944, 2.3 million doses of penicillin were available for the D-Day invasion. And in 1945, Fleming shared the Nobel Prize with Florey and Chain, who had developed the mass production method. How does that timeline of drug development compare with today?
Second, despite the nitpick, I want to speak up and congratulate you on your expanded coverage of science beyond physics. You are just as readable, understandable, and enjoyable as ever, and the diversity is good for all of us.
BTW, if you want a good read that is both an excellent introduction to the history of microbiology and an excellent example of science writing, let me recommend the 1926 classic Microbe Hunters by Paul de Kruif -- one of the best selling trade science books of all time. It's probably still on the shelf in your local library, and it's also still in print after 82 years. http://www.amazon.com/Microbe-Hunters-Paul-Kruif/dp/0156027771
Posted by: chezjake | May 20, 2008 at 10:42 PM