SearchResearch Challenge CONTINUED AGAIN! (Can you build an interactive widget for the island viewing problem?)

Since there's so much interest... 

... and since we seem to be making progress (see the comments in the last two posts), I'm going to continue this Challenge until next week.  My answer / analysis will be posted on Monday, May 1st.  

(We're so close.  Keep on trying!) 

Remember that the SearchResearch Challenge this week is to figure out how to make an interactive widget that can interactively show the relationship between height and visible distance in the "island viewing" problem.  That is:  

1.  Can you make an interactive widget that illustrates "how far out to sea can you see" without going into full-developer mode and writing a bunch of HTML, CSS, and Javascript?  

The comments from the last week have been pretty helpful, but nobody's got a solution yet.  It's possible that there isn't a good solution (that is, without going fully into HTML/Javascript), but we're tantalizingly close!  


Keep searching!  

 


----- 
I'm repeating the statement of what the widget should look like below... 


To get you started, here's a side-by-side sketch of what such a widget might look like.  In the first image, the observer's eye is 1.7 meters above the beach, which lets the observer see 4.7 km out to the visible horizon.  

The interaction is simple:  As you drag the red dot up, the value of the "height above the beach" changes.  In this image, it's 100m.  You can drag it down to 0, or up to a much higher number.   As you drag, the widget updates the "visible distance" number as you drag, and redraws the red line to touch a point on the circle (in this case, one that is 36 km out). 

In this next image, I've dragged it down a bit.  Here it's just 1.7 meters above the beach, and the red dotted line only goes out 4.7 km. As I drag the dot, the numbers should update, the line to the dot should move up and down, and the line to the point on the circumference of the circle should slide along to show the distance.  

NOTE:  These are sketches of what the widget might look like. They're NOT images from a working widget.  

The formula connecting these two variables look like this: 

     distance = 3.7 * (height ^ 0.5)  

where height is in meters, and distance is in kilometers.  (In the top example, since the height is 100m, the  square root of 100 is 10. Hence,  10 * 3.7 = 37 km.)  

SearchResearch Challenge CONTINUED! (Can you build an interactive widget for the island viewing problem?

Let's work on this a bit longer... 

Remember that the SearchResearch Challenge this week is to figure out how to make an interactive widget that can interactively show the relationship between height and visible distance in the "island viewing" problem.  That is:  

1.  Can you make an interactive widget that illustrates "how far out to sea can you see" without going into full-developer mode and writing a bunch of HTML, CSS, and Javascript?  

The comments from the last week have been pretty helpful, but nobody's got a solution yet.  It's possible that there isn't a good solution (that is, without going fully into HTML/Javascript), but we're tantalizingly close!  

One thing I found that helped was to use somewhat different search terms.  

I found a lot of interesting tools by searching like this: 

     [ interactive animation tools ] 

or 

     [ interactive tool for physics animations ] 

How did I come up with these search terms?  Easy.  I just described what I was looking for to a friend.  As I "translated" what was in the SRS post into everyday speech, I realized that I wasn't searching for a way to "build a widget," but I was looking to find a way to build an interactive animation.  

You know, it's funny to think about this because... once upon a time... this was simple to do in Apple's now-defunct scripting tool, Hypercard.  (Here's a longish demo of Hypercard.)  Of course, this was in pre-WWW days, but thousands of teachers were able to easily create content -- including interactive animations to illustrate physics.  

In any case, let's keep on this task for the rest of this week.  

I'll pop back in on Wednesday with an update on how I'm doing.  

Keep searching!  

  




----- 
I'm repeating the statement of what the widget should look like below... 


To get you started, here's a side-by-side sketch of what such a widget might look like.  In the first image, the observer's eye is 1.7 meters above the beach, which lets the observer see 4.7 km out to the visible horizon.  

The interaction is simple:  As you drag the red dot up, the value of the "height above the beach" changes.  In this image, it's 100m.  You can drag it down to 0, or up to a much higher number.   As you drag, the widget updates the "visible distance" number as you drag, and redraws the red line to touch a point on the circle (in this case, one that is 36 km out). 

In this next image, I've dragged it down a bit.  Here it's just 1.7 meters above the beach, and the red dotted line only goes out 4.7 km. As I drag the dot, the numbers should update, the line to the dot should move up and down, and the line to the point on the circumference of the circle should slide along to show the distance.  

NOTE:  These are sketches of what the widget might look like. They're NOT images from a working widget.  

The formula connecting these two variables look like this: 

     distance = 3.7 * (height ^ 0.5)  

where height is in meters, and distance is in kilometers.  (In the top example, since the height is 100m, the  square root of 100 is 10. Hence,  10 * 3.7 = 37 km.)  

SearchResearch Challenge (4/19/17): Can you build (or find) an interactive widget for the island viewing problem?

I found myself trying to explain... 

... the "how high you have to be above the shore to see the Farallons" SRS Challenge to a friend.  

You remember the original Challenge about seeing the Farallons.  The question there was "can you see the Farallon Islands from the western shoreline of San Francisco?"  

There was an interesting observation in that post.  It turns out that you can see them from the bluff over the shore, but not when you're standing on the shore itself.  

We figured out that the explanation (ignoring atmospheric refraction effects) was that you have to be some distance above the sand in order to see the islands.  The question was really how high do you need to be to see the base of the islands?  

I told my friend about the math involved, waved my hands a lot, and drew a few diagrams on a piece of paper.  But sometimes, that's a bit, well... handwavy.  What I really wanted was a simple interactive graphic.  You know, the kind where you move the slider up and down, and it shows you how far out to sea you can see.  

An example of such a widget can be seen at the Physics Classroom Interactive Lens web page.  Here's an example: 

Side-by-side images from Physics Classroom, an interactive lens tool.
If you slide the focus slider (f) and the height slider (H), the image above changes in real-time
to show the relationships between focal length and the height of the original image.  

In this widget, when you slide the f and H sliders to the left or right, the paths of the lines change as you wiggle the variable values around.  

The Challenge this week is to figure out how to make such a thing to interactively show the relationship between height and visible distance.  

1.  Can you make an interactive widget that illustrates "how far out to sea can you see" without going into full-developer mode and writing a bunch of HTML, CSS, and Javascript?  

This Challenge is really for the teachers out there, who might like to make such a widget to help illustrate and teach a particular point.  But I suspect that having the ability to make these little instructive interactables would be a handy sensemaking tool in general.  

The REAL Challenge is to find a tool that will help you make such a thing. Once you find that tool, use it to make a simple interactive widget that illustrates this height-over-the-sand to visible-distance relationship.  



To get you started, here's a side-by-side sketch of what such a widget might look like.  In the first image, the observer's eye is 1.7 meters above the beach, which lets the observer see 4.7 km out to the visible horizon.  

The interaction is simple:  As you drag the red dot up, the value of the "height above the beach" changes.  In this image, it's 100m.  You can drag it down to 0, or up to a much higher number.   As you drag, the widget updates the "visible distance" number as you drag, and redraws the red line to touch a point on the circle (in this case, one that is 36 km out). 

In this next image, I've dragged it down a bit.  Here it's just 1.7 meters above the beach, and the red dotted line only goes out 4.7 km. As I drag the dot, the numbers should update, the line to the dot should move up and down, and the line to the point on the circumference of the circle should slide along to show the distance.  

NOTE:  These are sketches of what the widget might look like. They're NOT images from a working widget.  

The formula connecting these two variables look like this: 

     distance = 3.7 * (height ^ 0.5)  

where height is in meters, and distance is in kilometers.  (In the top example, since the height is 100m, the  square root of 100 is 10. Hence,  10 * 3.7 = 37 km.)  

To start off, see if you can find a toolkit that will let you make a simple widget--that is, one that lets you slide a slider.  (Don't worry about drawing the diagram on your first pass.)  Then, once you get that working, try to add in the diagram. 

Fair warning:  I don't know how hard this Challenge will be--I haven't solved it yet (or really started it).  On the other hand, this is much more like the SearchResearch Challenges analysts solve in their day-to-day work.  

I'll be fascinated to see what we can come up with.  

When you get something working, put it into a web page and post your URL to the comments section.  I'll collect them (along with your comments about how to answer the Challenge) next week. 

If it's going slowly, I'll give some hints over the next few days (and maybe extend the Challenge for a second week).  

As always, let us know what you're thinking about as you search.  What queries did you do?  What were your experiences in finding a tool to help build this thing?  How did you figure it all out? 


Search on!  

Answer: Is that true?

True, or False?  

Answering these three questions was pretty straightforward. But as I discovered in the comments, our Regular Readers went farther into these topics than I ever imagined.  Bravo, Readers!  Bravo!  

Let's see what we can discover to answer these Challenges.   

1.  Is it true that some kinds of female sharks use only one ovary to produce eggs?  (That is, only one ovary actually produces eggs, the other is just kind of there?)  

I started with a simple search that focuses on the question: 

     [ sharks only one ovary ] 

I assume that if this was true, then anyone writing about it would probably write about "only one ovary."  I didn't search for a quoted phrase ("only one ovary") so as to not over-limit the results.  Google prefers words that are in the order presented in the query.  So the phrase only one ovary would be prefered over those same words scattered all over the page.  

In any case, this search led me to the paper Morphological analysis and description of the ovaries of female silky sharks, Carcharhinus falciformis in the journal Neotropical Ichthyology, 11(4):815-819, 2013.  In this paper the authors write that: 

In several elasmobranch species, only one ovary is functional. Such is the case of the species within the genus Carcharhinus, Mustelus and Sphyrna. Oviparous species have both ovaries developed and functional, such as of the species Pristis cuspidatus and Squalus brevirostris.

Interesting.  Some sharks have only one working ovary while some have two.  

This is definitely something to second source.  I recognize the name Carcharhinus as the genus name for Requiem sharks (a kind of shark that includes Tiger sharks, Silky sharks, Blacktip sharks, etc.).  

I thought I'd try to confirm this uni-ovary characteristic in Requiem sharks by searching for: 

     [ Carcharhinus ovary ] 

which led me to the Wikipedia entry on Blacktip sharks (a kind of Requiem shark).  In there we not only confirm that Blacktip sharks have only one functional ovary, but also that... 

Females have one functional ovary and two functional uteri; each uterus is separated into compartments with a single embryo inside each. The embryos are initially sustained by a yolk sac; in the 10th or 11th week of gestation, when the embryo measures 18–19 cm long (7.1–7.5 in), the supply of yolk is exhausted and the yolk sac develops into a placental connection that sustains the embryo until birth.

More interesting!  Two working uteri, AND the shark starts off life with a yolk sac (as part of an egg) and then changes that yolk sac into a working placenta!  Sharks are amazing creatures, in many ways. Including, apparently, working other kinds of natal miracles.  

In 2007, a 9-year-old female blacktip shark at the Virginia Aquarium and Marine Science Center was found to be pregnant with a single near-term female pup, despite having never mated with a male.  

As evidence, see: Chapman, D.D.; Firchau, B. & Shivji, M.S. (2008). "Parthenogenesis in a large-bodied requiem shark, the blacktip Carcharhinus limbatus". Journal of Fish Biology. 73 (6): 1473–1477.  The second sentence of that article is a doozy. "The parthenogenetic embryo exhibited elevated homozygosity relative to its mother, indicating that automictic parthenogenesis is the most likely mechanism."  That is, the baby is more-or-less identical to its mother, which tells us that no boy sharks were involved in the making of this pup.  

AlmadenMike points out that this fact has been known for quite a while. For example, on page 1461 of this book published in 1842 (Elements of Physiology, Part 2, Volume 2 by John Müller) we find that biologists have known about single-sided working ovaries in both some sharks and some birds.

But Remmij found a fantastic video of a dogfish dissection showing the location of the ovaries (remember dogfish from our earlier SearchResearch Challenge?).  Unlike mammals, female sharks have their ovaries in the same body location as male sharks have their testes.  (Don't watch this if you're squeamish; but if you don't mind watching a fish being scissored open, it's really quite interesting.)  

2.  Is it true that tinnunculite is a real mineral?  If so, what does it have to do with kestrels (the raptor)?  (I ask because I recognize the name tinnunculus as the species name of the European kestrel.  If it's real, what's the connection?)

This was an interesting search!  Just doing the obvious search: 

     [ tinnunculite ] 

gives us a spelling correction and lots of information about kestrels.  

That's fine, but I want to learn about the mineral (if it exists).  I had to quote it: 

     [ "tinnunculite" ] 

to get a good result. When I do this search, I find that Wikipedia tells us that  it is a "naturally-occurring mineral that forms when droppings from a European kestrel react with the burning dumps of coal mines and quarries." It's formula is C5H4N4O3 · 2H2O

What?  Really? 

The article then tells us that "The mineral is a dihydrate of uricite to which it is visually very similar. Tinnunculite is chemically similar to other organic minerals: guanine, uricite; also acetamide, kladnoite. A mineral of the same name but different formula (C10H12N8O8) was rejected by the IMA/CNMNC."  

Hmm.  This sounds suspicious.  But following up on other results quickly leads us to the Mineralogical Society's page on the substance, which tells us that it is now approved (as a formal mineral name) pending publication.  (For full details about the controversy, read AlmadenMike's masterful summary of the debate in the comments of the Challenge.)  

In the end, this is actually a mineral of anthropogenic origin (that is, caused by human activity, even though it's really kestrel poop interacting with burning coal--since people caused the coal to catch fire, its considered human-caused, even though as we found in an earlier Challenge, not all long-lasting coal fires are started by humans).  

Tinnunculite - P/C Mindat.org 

3.  Is it true that the journals Science and Nature are going to team up and form a new journal together? (They have long competed to be the world's preeminent scientific journal, so this was a surprise to read.)  

I did a search for: 

     [Science Nature "new journal"] 

and found an article on the Science journal site discussing the potential new journal.  

But notice a couple of things about this article.  First, it's written by a well-knwon science writer John Travis. That checks out.  But the tone is off and the premise is pretty surprising. Both journals will cease publication?  And they haven't decided the name of the new journal, but are letting text-messaging votes determine the name?  

That's when I noticed it was published on April 1, 2010.  Got it.  This is an April Fool's joke.  

Then the rest starts to make a jokey kind of sense:  "... the first 100 new subscribers will get free genome scans" and the article quotes a magazine consultant named Rick Rolling (and offers a link to the Wikipedia page for that Internet meme).

It's handy to know that "Science" has a long tradition of April Fool's Day articles that pull your leg. This is one of those. 

So no, the journals are not planning on merging.  

Search Lessons 

1. Not everything you read on the internet is true.  Yeah, I know... WE know that, but it's useful to remember that not everyone is quite as discerning.  In this case, we found that ever articles from respected journals sometimes need a bit of careful reading.  (Especially in April!)  

2. Double quoting a single word turns off spell-correction.  That's how we had to get to the Tinnunculite results.  

3. A strategy for checking on a complex idea is to check a specific case.  That's why I checked for the "one ovary" just within the Requiem (Carcharhinus) shark species.  If it was true of the entire genus then someone, somewhere must have written an article about that large and distinguished genus of sharks.  


Search on! 

SearchResearch Challenge (4/14/17): Is that true?

True, or False?  

One of the biggest questions in these slightly strained days of fake news is whether or not something is true.  

Without getting all epistemological on you, for this week's Challenge I have a few questions that have come up in my reading over the past few weeks.  These are items that I found and puzzled over.

Each time I wondered--Is that true?  

Each time I did a bit of SearchResearch and found the answer fairly quickly.  But each case was a surprise.  

Since we're slightly off on our regular schedule (this week was busy, so it took me a couple of extra days to get the time to write to you), I'll issue this Challenge today and answer it next Tuesday (April 18).  Then we'll get back onto the regular Wednesday Challenge / Monday Answer cycle.  

Here are three "Is it true?" Challenges for the week.  Each one is fun, and shouldn't take you more than a minute or two to find the answer.  (But I suspect you'll enjoy looking them up.)  

1.  Is it true that some kinds of female sharks use only one ovary to produce eggs?  (That is, only one ovary actually produces eggs, the other is just kind of there?)  

2.  Is it true that tinnunculite is a real mineral?  If so, what does it have to do with kestrels (the raptor)?  (I ask because I recognize the name tinnunculus as the species name of the European kestrel.  If it's real, what's the connection?)

3.  Is it true that the journals Science and Nature are going to team up and form a new journal together? (They have long competed to be the world's preeminent scientific journal, so this was a surprise to read.)  

Let us know your answers and what, if any, difficulties you had in figuring them out! 

Search on! 

Answer: You mean.. they explode?

Zounds!

It's true: some plants DO explode, including ones that look quiet and serene in botanical gardens

Waimea Arboretum

As I did this research, the biggest surprise to me was that there are a LOT of plants that explode.  Luckily, most of them are reasonably small and gentle.  But there are some that can be deadly.  

The comments this week were especially fantastic.  This week I'm going to lightly edit Regular Reader Mike's answer because it was great.  Nice job, Mike!  (I've added my comments in a different font so you can see them.)  

Remember that the Challenges this week are:  

1.  Are there, in fact, dangerous trees that can somehow eject sharp bits of themselves, potentially hurting a human being?  (If so... HOW would it do this?  So far as I know, few plants - venus fly traps aside - are capable of much movement.)   

2.  More generally, are there other plants that can hurl seeds?  You can imagine this might be a handy evolutionary mechanism to have--but again, how would that seed-hurling mechanism actually work?  Do they have little plant muscles??   

AlmadenMike writes: 

‟A few years ago, I let a small section of backyard grass go untended before a remodel that would replace it with a patio. When it went to seed, I experienced a spectacular ankle-high show of seed-spouting fireworks with every step. Merely brushing against my pants was enough to set off the blasts. I thought I’d start with this search to try to identify that grass and go from there:

     [grass projectile seeds]

But the fourth hit was an article in a gardening blog that described the entire phenomenon: Examples of plants that disperse seeds by shooting them.  

The article starts: 

“Some plants disperse their seeds forcefully by ejecting them. Sometimes the tension is so great, seeds may be ejected up to 200 feet away from the mother plant. This method of seed dispersal is called ballistichory, a label that hints at the projectile-like emergence of seeds from their pods or capsules. This type of seed dispersal occurs because the fibers in the dried fruit pull against each other to create tension, and when the tension is great enough, the fruit splits open and the walls of the fruit spring back, flinging the seeds out with force.”

It listed four plant families that had significant ballistichoric seed ejections: Pea family (Fabaceae), Euphorbia (Euphorbiaceae), Acanthus (Acanthaceae) and Mallow (Malvaceae). "In the pea family are “Orchid trees” (Bauhinia spp.), (which) bear large pods that can fling seeds nearly 50 feet."

I didn’t see any plant list for the Waimea Arboretum or Botanic Garden ... and no searches for those places and “dangerous tree” got any hits. But I thought your “dangerous tree” might have been a Bauhinia. 

Searching for:

    [bauhinia ballistichory] 

led to this informative article (second hit) about two more capable exploding seed capsule trees.  It's called, "Going Ballistic."  From the article:  

“One interesting example from the tropics is the genus Pentaclethra, a relative of Bauhinia. An experienced botanist reported that Pentaclethra was the only plant he knew whose pods opened so explosively and forcefully that they could break the sturdy oaken presses that botanists use to press and dry their plant specimens. For all its press-shattering strength, Pentaclethra throws its seeds only about 33 feet from the parent tree, which, ironically, is not as far as the gentle Bauhinia. Just for the record, the world champion ballistics title belongs to an African tree in the Legume family, Tetraberlinia moreliana, which throws its seeds almost 200 feet!”

The latter may have come from the 1997 paper: “Explosive Seed Dispersal of the Rainforest Tree Tetraberlinia moreliana (Leguminosae - Caesalpinioideae) in Gabon” by Xander M. Van Der Burgt, (Journal of Tropical Ecology - Vol. 13, No. 1 (Jan., 1997), pp. 145-151).  (You can find this paper by searching for [ Tetraberlinia moreliana seeds ] in Google Scholar--it's the first hit.  In this paper I read that: 

“The dehiscence [i.e., the rupture of the seed pod] is caused by tension that builds up between the two valves [sides of the seed pods] during drying. Mature pods explode with a crack during periods of sunshine.”

One tree he monitored produced an estimated 15,000-20,000 seeds, with 1.5-2% of those seeds projected over 50 meters away. The longest distance was 60 meters (nearly 197 feet). (With discussions of launch angle and wind-speed dispersions, this paper read almost like an analysis of a golfer testing drivers.) The author also speculates that such explosive dispersal is handy for "...high forest trees, from which large seeds lacking dispersal
devices are thrown many metres away."  

[ Dan:  I couldn't help but include a diagram fro Van Burgt's paper. It neatly summarizes why plants would develop such explosive seed dispersal mechanisms...] 

Van Der Burgt’s paper also mentions that the exit velocity for the test tree was 37.1 meters/second … which was less than nature’s fastest.  That high speed mark belongs to Hura creptitans, aka Sandbox tree or Dynamite tree, which launched its seeds at 70m/s (157 miles/hour). 

This tree, Hura creptitans, may well be your “dangerous tree.” (FWIW, The sap is also poisonous.)

Googling simply: 

     [“Sandbox tree” danger] 

turned up a host of articles and videos. Among the best is this article from a gardening blog, Sandbox Tree Facts.   

“Considered one of the most dangerous plants in the world, the sandbox tree isn’t suitable for home landscapes, or any landscape actually. … Sandbox tree fruit looks like little pumpkins, but once they dry into seed capsules, they become ticking time bombs. When fully mature, they explode with a loud bang and fling their hard, flattened seeds at speeds of up to 150 miles per hour and distances of over 60 feet. The shrapnel can seriously injure any person or animal in its path.”

I found two videos (although none show the H. crepitans seeds exploding on their own without a tap to get them going).  

This is a nice video of Hura crepitans (Sandbox tree), showing its formidable spines:   (https://www.youtube.com/watch?v=AKEgrmfHWX0)

and a Smithsonian Channel video of several exploding-seed plants including the remarkable exploding cucumber, worth watching on its own (as it's an example of explosive seed dispersal that uses fluid pressure, not dehiscense to eject its seeds). Unfortunately, there's no Sandbox tree in this video.  It's still worth watching: https://www.youtube.com/watch?v=NsIojj4PzAo 

The “Going Ballistic” article also succinctly described the ballistichory mechanism: “All of these plants rely on the drying of the fruit wall to generate tension. The wall of a ballistic fruit has at least two layers in which the woody fibers are oriented in different directions, usually at right angles. As the woody fibers dry, the layers pull against each other. When at last the fruit fractures along a predetermined seam or weak spot, the walls curl, throwing the seeds a considerable distance. … It is the drying of the fruit that supplies the tension.”

So my answers to your questions would be:

1) Several trees do eject their seeds with an explosive speed of 30-70 meters per second that can send them nearly 200 feet away. One could imagine that it might be hazardous to stand very close to one of the seed pods at the time of its ballistichoric dehiscense. Especially those of the Sandbox/Dynamite Tree, Hura creptitans.   

2) Yes, quite a few plants eject their seeds with explosive force. The mechanism (described in more detail above) involves increasing tension within a seed pod as it dries, and explosive ejection of the seeds when the pod eventually ruptures.

Finally, after finding all this, I did not look further to identify the grass that I’d had in my backyard.  

_____________________________

AlmadenMike has it right. The magical words to know here are dehiscense and ballistichoric. Once you start running into technical terms in the middle of your search, its time to start paying attention--especially once you look them up and learn that these concepts are central to what you seek.  

Similar topic search:  Mike started his search by looking for explosive dispersal of seeds, and then learned the word "ballistichory," which then led him to the Bauhinia plant, which led him to the Sandbox Tree, Hura creptitans.  

I followed a similar path, but started with the query: 

     [ explosive seeds Hawaii ] 

which got me to Hura creptitans fairly quickly.  

Once I knew the Latin name, a YouTube search found me a video of the fruit exploding (after being hit with a piece of wood).  https://www.youtube.com/watch?v=lNlk2V9yFhM 

Look twenty seconds into this video for the impressive explosion, which would account for the sounds I heard in the arboretum.  

And, just to verify that this was the tree that I'd walked near, I did this search: 

     [ Hura creptitans Waimea ] 

I will admit that I ended up having to go to Google Images as a way to ensure that there IS a Hura creptitans at the Waimea arboretum.  (Like AlmadenMike, I wasn't able to find a plant list for the arboretum.  I'm sure they have one, but not online.)  

In any case, my Google Image search led me to a Pictaram image collection of Hura creptitans (who knew such a thing would exist?), and in that collection, there are a couple images of the Sandbox tree with the hashtags #arboretum and #WaimeaValley.  That convinces me that there really is at least one Sandbox tree in the Waimea Arboretum.  

P/C Ronald Casallas

AlmadenMike started his search by looking for a rapidly ejecting grass seeds.  Luckily, I remembered seeing such a thing in my own yard, and was able to find out what causes it.  (And, double lucky, AlmadenMike also live in the Silicon Valley.)  

I tracked my "exploding grass seeds" to the Yellow Woodsorrel (Oxalis stricta).  Wikipedia tells us that: "The mature seed capsules open explosively when disturbed and can disperse seeds up to 4 meters (about 13 feet) away." There's a lovely video of these seeds ejecting when touched by a human... https://www.youtube.com/watch?v=RhGib39KfSk 

I will tell you from personal experience that when the conditions are right, touching just one seed pod can cause it to fling seeds every which way, causing a kind of mass seed ejection chain reaction, when thousands of seeds from neighboring seed pods are sent flying after being hit by an errant seed.  

Search Lessons 

1.  Search for a parallel that you know about.  I really liked AlmadenMike's strategy of searching for something he already knew about (the exploding grass seeds), and then learning what terms he should use in later searches. From an article about exploding grass seeds he picked up the word "ballistichory," and was able to use that term to focus in on ballistichoric tree pods and seeds as well.  

2. Learn to notice special technical terms.  Before starting this search, I'd never heard of dehscience, OR ballistchory.  While they probably won't be part of my everyday speech, they're exactly the right words to use in this bit of research.  By using specialty terms, your chance of finding exactly the right concept is improved.  (But be sure to get the right definitions... you don't want to use the wrong technical term!)  

3.  Sometimes Images are where you'll find the connection.  Honestly, I was expecting the Arboretum to have a plant list, or at least an online page highlighting some of their more spectacular plants.  But I wasn't able to find that.  However, by using Image search I was able to discover at least one person who knew that there is a Sandbox Tree at the Waimea Arboretum.  

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FLASH UPDATE!  

As I was writing this blog post, I got an email from Regular Reader Ramón who took the initiative to write to the Director of the Waimea Arboretum to ask about explosive plants.  

He wrote: 

"[I'm searching in the Waimea Arboretum for] .. a tree that has ballistic seed dispersal and we trying to find more information about it. [Dr. Russell] will give an answer next week. But, the intention is to find the information before searching online. 

Do you have more information about what tree is this in the valley? Maybe is not a tree but a plant."

And the Director wrote back! 

"What Dr. Russell mentioned could be these trees: The rubber tree Hevea brasilliensis or the Sandbox tree – Hura crepitans.  There may be others but these are what came to my mind.  Thanks, Josie."

This makes it pretty clear that it could be one of these two plants.  Both have explosive seed dispersal mechanisms.  

This leads to a 4th Search Lesson: 

4.  Ask questions of people who know.  Ramón's method of simply writing to someone who knows can be a real life-saver when dealing with complex research questions.  Google is great, but so are people--especially experts who are right there and can check the ground truth for you.    

After all this, my bet is on the Sandbox tree as the source of the overhead crack, whiz, and zing.  

Why?  

I forgot to mention that I also remember standing near a large, very dangerous-looking spiny tree when the seed pod flew overhead.  It's possible that I was looking at the Sandbox tree while the rubber plant seed exploded behind me, but it seems unlikely.  

Of course, maybe I'll have to return to the North Shore of Oahu to find out... 

Search on! 

SearchResearch Challenge (4/5/17): You mean.. they explode?

Crack.... Zing!

I'd been walking through a quiet and peaceful botanical garden when it sounded like something blew up not far from me.   What's going on?? 

A millisecond later I heard something whizzing overhead--an angry bee sound of something passing overhead at high speed.  

It seemed unlikely that anyone was shooting at me--this was the Waimea Arboretum after all--but I couldn't just ignore this high velocity drama overhead. 

Waimea Arboretum Pond

I DO remember seeing a sign about a "dangerous tree" on the garden pathway, but I'd just assumed it might fall down onto the path, not that it might fire high velocity projectiles in my general direction.  I thought it would be a peaceful stroll, not the wild west!  

Still, I should have suspected something like this.  Just a week before I'd been looking at the seed pod of a clover-like weed in my front garden.  To my surprise, when I touched the long, oblong seed pod, lots of tiny seeds zipped past my poking fingers and pattered on the nearby foliage.  Luckily, these seeds were about the size of poppy seeds, so there was no possible harm.  

I never did figure out what that high-velocity plant particle was in Waimea.  More generally, are there other plants like that?  Are there other plants capable of suddenly spewing out parts of themselves at high speed?  

The Challenges today:  

1.  Are there, in fact, dangerous trees that can somehow eject sharp bits of themselves, potentially hurting a human being?  (If so... HOW would it do this?  So far as I know, few plants - venus fly traps aside - are capable of much movement.)   

2.  More generally, are there other plants that can hurl seeds?  You can imagine this might be a handy evolutionary mechanism to have--but again, how would that seed-hurling mechanism actually work?  Do they have little plant muscles??   

Let us know what you discover.  It seems improbable, but I'll be searching with you this week, trying to see what we can discover about potentially dangerous plants!  

Search on! 



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P.S.  BTW .... There was a bug in last week's Challenge.  When I wrote the Challenge, I know there was EXIF metadata on the last image--but something obviously changed.  I'm in the process of debugging it right now.  I'll let you know what I find out in an upcoming post.