Sciency Answers: Another sticky question.

I got this question from Susan Sims:

What is that gummy, sticky film between the paper and the fruit on a tomatillo?

...and why is it there?

Eagerly awaiting a reply,

--Susan

My Sciency Answer:
It is all part of a scheme to make sure bugs don't eat the fruit, but birds do. Birds eating fruit is a good thing because then they fly around and poop the seeds out everywhere. But the birds can't eat it if the bugs get to it first. Tomatillos keep the insects away with a two-part defense system: Bad tasting chemicals, backed up by the sticky stuff Susan asked about.

The bad-tasting chemicals are called withanolides. The mature tomatillo makes lots of these in the little paper jacket (technically, the calyx) covering the fruit, but little of it in the fruit itself. Birds can pull off the gross husk and eat the yummy fruit, but insects just start eating, go "ick!" and fly away.
Which seems like a great system. So why does the tomatillo also make a layer of sticky? Because very small insects can slip in under the papery husk through an opening at the end. Very clever, these tiny little evil insects think themselves to be, but, before they can start to eat, they find themselves caught in the sticky layer and die. Bwahahaha!

So, to recap: Tomatillo protect their fruit from insects first with a foul-tasting papery covering, and then, just in case that defense is breached, they also make themselves into flypaper with sticky stuff, to keep their fruits pristine and perfect for hungry, seed pooping birds.

My explanation is primarily based on Chemical defence by withanolides during fruit development in Physalis peruviana by Baumann and Meier, so you can check out all the gory details there if you are so inclined.

Have a question? Send me and e-mail (engeizuki at gmail dot com) and I'll provide a sciency answer!

Another reason to mail order your bulbs?

I got a flower bulb catalog the other day from Colorblends. It was a bit late for me as I always put in my bulb orders back in June to take advantage of early-bird sales from my prefered source, McClure and Zimmerman, but I never turn down a chance to browse a catalog. One thing caught my eye: They had a little essay explaining that most daffodils sold in stores in the US are harvest and shipped too early, before they've had a chance to mature and dry properly, because big box stores demand early shipment to get their displays up early, and most independant garden centers feel forced to follow suit in order to compete. They say this makes the bulbs significantly more succeptable to fungal damage in shipment.

I always mail order my bulbs anyway (aside from a few impulse purchases) for the better selection and better prices. Guess you can add "not harvested too early" to that list as well.

Friday Cartoon: The bulb cycle

Where are the violas?

I used to say pansies and violas just weren't worth growing. Here in the midwest winter slips pretty quickly into summer, with only a brief bit of spring in between, giving a spring planted pansy only has a few weeks to get growing and flowering before it lives up to its name and wimps out in the summer heat. My opinion changed one year when I saw a neighbor plant one -- just one, for some reason -- yellow pansy in the fall. It gave a decent show for a few weeks, then disappeared under the snow. I though that was the end and had forgotten about it until the snow finally melted and almost instantly, while the rest of the world was still half-frozen mud, that lone pansy started stopping traffic with a solid mass of flowers.
I learned my lesson. Pansies and violas, like tulips and daffodils, really ought to be planted in the fall so they can get established, overwinter, and start pumping out blooms while everything else is still underground. So why, of why, doesn't anyone have them for sale? I stopped at a local independent garden center last week. It had been overrun with pansies and violas in the spring, so I expected to find a good selection -- but no such luck... not a single one to be seen. I stopped at a big box store for another errand and found a measly selection of pansies. I bought a few even though I prefer the smaller flowers of violas better, and even though they were a mix of colors half of which I didn't want, because something is better than nothing. Once in they were in the ground, I knew I needed something better, so I trekked out to the good garden center, the one that is a good 30 minute drive away and has all sorts of cool stuff, confident they would have the cute, tough, smaller flowered violas I want in a wide range of colors. Ha. They had just a few pansies too, even less selection than the big box store. I was devastated and had to comfort myself by browsing through the discounted perennials and buying a dozen Digitalis thapsi for only a $1.50 each. This put me in a better mood, and I did end up buying a few trays of their pansies.

So I had to settle for pansies. Pansies which are pretty, of course, but I wanted violas. I was ready to spend vast amounts of money on violas to ensure that I would have a knock-out show next spring and... no luck. Independant garden center owners, if you are listening, this is why I end up spending less and less money every year at your stores, and more and more on mail order seeds. Now I know that if I want violas in the fall, I'm going to have to order seeds and grow them myself. Unless anyone knows of somewhere selling violas right now in Michigan?

On the radio -- again!

I'm on The Splendid Table again this weekend talking about breeding tomatoes! Download the podcast to hear all the fun!.

If you are a Splendid Table listener visiting for the first time, welcome to my plant obsessed universe!I hope you'll poke around, comment, and ask questions. Check out my cartoons, my obsession with slightly odd plants, or my sciency stuff.
If you are curious about plant breeding, I have complete instructions on how to breed your own tomato here (it is really easy -- I promise) and if you need more convincing, I wrote a slightly over-the-top essay (I get excited about this stuff...) about why plant breeding is so awesome here.

Friday Cartoon: Buying Bulbs

I was at the grocery store, and they had a big display of bulbs for sale. I already put in a huge order for bulbs, but....

The United States of Amsonia: A manifesto

Last week I read The United States of Arugula by David Kamp. It is a fun little history of the rise of the food movement in the US -- starting with the early ground breakers like Julia Child and James Beard all the way to today's world of foodies and celebrity chefs.
While reading it, I kept thinking: When is this going to happen to the plant world? When will we be talking about celebrity gardeners?
In the early pages of the book, it was almost the same story over and over: the future food world star grows up never really having thought about food, only to discover (usually on a trip to France) this whole other universe: food not just as a source of calories, but rather Food as Art. Food as something important to be thought about, talked about, and lived for. As the movement matures, people have the same epiphany all over this country as they discover for the first time that there is something beyond canned vegetables and processed cheese food product -- food that is worth being passionate about.
What I realized is this: people in the pre-Julia Child James Beard US didn't ignore food because they weren't interested -- they had simply never thought of it, had never had it presented to them quite that way. The same is true for gardening. This country is full of people who are not passionate gardeners simply because they've never thought of gardening as something to be passionate about. All over this country, people are living with the gardening equivalent kraft macaroni and cheese -- chemical soaked, unnaturally green lawns and a few pots of uninteresting, scentless petunias -- when they could be reveling in the joyous wonders found in the pages of catalogs of companies like Plant Delights, Arrowhead Alpines, and Annie's Annuals.
It is time we gardeners stood and up and showed the rest of the country what they are missing. Time we declared that a horticultural masterpiece like the Lurie Garden in Chicago is every bit as significant a piece of art as the paintings housed in the more traditional art museum next door. Time we spoke of gardening as a passion for a life time, as the way to live connected with and supporting nature rather than destroying and abusing it. Time we said the word "gardener" with every bit of smug self-satisfaction heard in the voices of people calling themselves "foodies."
I think the time is right. The food movement itself, combined with the economic troubles, are funneling more and more people into vegetable gardening -- a gateway drug to the other wonders of the gardening life. We have wonderful crop of gardening spokes people -- nursery men like Tony Avent whose politically incorrect catalog covers and plant descriptions state loud and clear that gardening is hip, writers and communicators like Ken Druse and Dan Hinkley who speak loud and clear about gardening and plants in all their complex, marvelous, endlessly entrancing glory. Here on the blogosphere, gardening is ranting, dangerous, punk, strange, quirky, funny, and just feakin' cool.
The revolution is coming.

More caterpillars eaten alive

I love wasps. I love them even more when they are killing caterpillars. Which was why I was excited to see this:

It is a tomato horn worm -- bane of the tomato growers existence -- covered with the pupal of a tiny little parasitoid wasp. A momma wasp finds a tomato horn worm, and cheerfully lays some eggs inside it. The little baby wasp larva hatch and happily munch on the innards of the caterpillar. Like all good parasitoids, they are careful to save the vital organs for last so the caterpillar doesn't die. Finally, they wriggle their way out of the body of the horn worm, build a little pupa (the white things in the picture) and transform themselves into lovely little adult wasps.
So so cool... Parasitoid wasps are the best. There are tons of different kinds -- some of which are so tiny they actually lay their eggs and grow up inside aphids!

Friday Cartoon: Signs of fall

I noticed a leaf the other day... a yellow leaf. My mind instantly was whirling.

Introducing: Sciency Answers!

Last week, I got an e-mail from none other than Annie of Annies Annuals! This made me squeal with excitement because I am a TOTAL nut case when it comes to horticultural celebrities (ask me about the time my friend Virginia and I ran into Dan Heims of Terra Nova at a trade show...), and I think Annie totally qualifies as one. She went on to say nice things about my blog (!!!!) and then asked me if I was up for providing "Sciency answers" to random questions about plants. To which I reply, "TOTALLY!"

And so, I introduce to you the newest Greensparrow Gardens feature: Sciency Answers! If you have a question requiring a sciency answer, just e-mail it to me -- engeizuki at gmail dot com -- and I'll get right on it.

Annie's question was why some plants exude gummy substances on their buds -- for example, Grindelia arenicola. She even sent a picture:

Gross.
But kind of cool. Now I want one.

So why do they? So they won't get eaten. Slimey grossness to avoid being eaten is a common theme for plants. The seeds of many species of salvia exude slime which has been shown to discourage things (mostly rodents) from eating them. If you have ever deadhead a petunia and come away with a grossified hand, you know they are covered with little sticky yucky hairs -- some scientists bred the sticky hairs away, and hey presto: Without the sticky yuck, the plants got gobbled up by whiteflies.
In the specific case of Grindelia, it appears that they are so serious about not getting munched upon that they they produce chemicals which show "feeding deterrency towards aphids" (see the paper here) so it appears they cover their flowers with yucky tasting glop so that when aphids and other insects stop by for a bite to eat, they end up grossed out and heading off to find something else for dinner.

Friday Cartoon: Tomato glut

Guest cartoon blogging a Studio G

If you want an extra dose of my cartoons this week, toddle over to the Studio G blog where you'll find me guest cartooning with a little drawing about garden designers. And check out her blog while you are there -- it is a great place for all kinds of design ideas.