Posts Tagged plant structure

the beauty of tiny things Alison Campbell Dec 05

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I loved playing with kaleideoscopes when I was (much) younger, but the images they produce have nothing on what Victorian microscopists achieved using diatoms.

Diatoms are single-celled photosynthetic organisms, and one of the things that really makes them stand out it the variety & beauty of their cell walls, which contain a very high proportion of silica: as the Tree of Life site says, they basically live in glass boxes. Collectively the diatoms make up one of the largest taxa on earth, one with considerable ecological significance: at about 40% of marine primary production, they produce >20% of our oxygen.

But back to their cell walls. Apparently, Victorian scientists were big on arranging these little organisms in complex patterns that derived much of their beauty from the cell walls found in different species. While the actual details of what they did weren’t recorded, Neatorama describes the work of Klaus Kemp, who has rediscovered their art & generated some stunning images of his own.

Images like this:

(Image credit: Klaus Kemp)

And watch the video here. This is wonderfully skilful work, & so beautiful, and I’ll share it with my students in next year’s classes.

most excellent epiphytes Alison Campbell Mar 28

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A couple of years ago I spent a lovely afternoon in the huge domed glasshouses of Singapore's "Gardens on the Bay". The 'cloud forest' was my favourite – both for the concept & for the wonderful range of epiphytes on show there.

Singapore cloud forest mountain.jpg

So you'll understand that I enjoyed reading about it again on this blog, written for the New Zealand Epiphyte Network. Anyone with even a passing interest in New Zealand's native plants should drop by the site. And maybe sign up to be part of their citizen science project while you're there?

Go on, you know you want to :)

teaching plant life cycles – trying a different approach Alison Campbell Mar 12

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For whatever reason, I find that many students seem to struggle when it comes to learning about plant life cycles. The whole sporophyte/gametophyte, meiosis/mitosis thing really gets them – & that’s even before we start looking at how the life cycle is modified in different groups of plants. Yes, the textbook has lots of diagrams & yes, I’ve always started simple & worked on from there, with opportunity for plenty of questions, but still there are those for whom the topic fails to click. (Not to mention the lecturers in third-year classes, asking whether we really teach this stuff in first-year.) This year the issue’s become even more of a challenge, given that about 2/3 of my large-ish (N>200) didn’t study plants in year 12 at school.

So this year I wondered if it would help if I drew a really basic cycle on the board, as preparation for a more detailed session in the next lecture. I do this in tuts anyway, but not everyone comes to those… And because I use panopto for recording lectures, I needed to think about the best way to do it, because while there are whiteboards in the lecture room they are non-interactive, & the camera doesn’t do a good job of picking up things on a ‘normal’ board. And this is where having a tablet (not an iPad this time; it’s too frustrating when mine won’t communicate properly with the lecture theatre software) comes into it.

This is because, once the tablet’s hooked up to the lecture room system, then anything I might write on its screen (with my spiffy little stylus) is recorded via panopto. And so I left blank slides in my presentation, & drew all over them when we got to that stage, cute little frogs & everything :) (Why frogs? Because we started off with drawing an outline of an animal life cycle, slotting in meiosis & fertilisation, haploid & diploid – with the opportunity to expand on what those terms might mean – before going on to drawing alternation of generations in a very general sense.

Which sounds fine in practice, doesn’t it? Unfortunately, now that I’ve gone & checked the recording, I see that the material on my tablet DIDN’T make it across to panopto, which is downright annoying & obviously I’ve stuffed up somewhere. OK, everyone in the lecture theatre got the benefit of that experience, but those who weren’t, didn’t :( And part of the reason for doing the recordings, is that those who’ve got lecture clashes can catch up later. Mutter mutter mutter.

However, all is not lost. I’m staying later at work for an evening event, so I’ll do a re-record once I can get into a free lecture theatre.

All part of the learning curve – as is the anonymised ‘feedback’ thread I’ve set up on our Moodle page. If the technique helped most students understand the concept of alternation of generations, then I’ll work on doing it better. If it didn’t, well, I guess I need to go back to the drawing board.

an entertaining take on plants & plant cells Alison Campbell Mar 02

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The new semester kicks off tomorrow & right now I'm adding resources to my first-year bio moodle page & running through the powerpoints for the week's lectures. After a couple of introductory sessions we're diving into the section of the class that focuses on plants, and I'm giving some serious thought to how I present that material given that it looks like more than half the class didn't study the relevant year 12 Achievement Standard. 

So among other things I've looked around for some engaging short videos on plant biology, and I found this one (part of what looks like a great sequence, which I've bookmarked for future use): 

OK, I know the humour might not appeal to everyone, & he does speak rather fast at times, but the presenter's engaging, the graphics are good & the key points are emphasised and repeated – a nice little primer for my class to watch for homework as preparation for making sense of plants.

presenting on plants at WCeLfest Alison Campbell Feb 16

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For the last few years our Centre for e-Learning has run WCeLfest – a day of presentations & discussion around using various technology tools to enhance teaching & learning. I always find these sessions very valuable as there are a lot of people doing some really interesting things in their classrooms, & there’s always something new to learn & try out myself. I offered to run a session myself this year, which is what I’m going to talk about here, but I was also asked to be on the panel for a discussion around what universities might look like in the future, and that was heaps of fun too.

My WCeLfest session was billed as a workshop, so to kick things off I explained that the attendees were going to experience being in what is effectively a ‘flipped’ class, getting the students’ perspective, and why I’d developed the class in the way that I had. (I added that feedback on that experience was welcome!) I think there was one biologist in the room, so for most of those present the things they’d be doing would be just as novel as they will be for many of my students.

First, my ‘class’ got some extra background information. If previous years are anything to go by, then about a third of the students in my first-year biology class won’t have studied the year 12 Achievement Standards related to plants1. This always poses something of a challenge as we run the ‘plants’ part of the paper first, flowers & fruit being readily available in late summer (& I doubt things would be different if we taught it later in the paper). So I’m always thinking about improved ways to bridge students into the subject without boring those who have a reasonable background in things botanical.

The first lecture looks at what plants are & why they’re important, both ecologically & in terms of human history. For the last 2-3 years I’ve used an active learning exercise, putting up a graph on changes in atmospheric oxygen over the 4.5 billion years of Earth’s existence and asking the students to interpret and discuss the information it shows. But, using the same graph with a different group of learners, I realised that some of my students might not even know what photosynthesis entails, which would rather destroy the purpose of that part of the class.

So this year, they’re getting homework for the night before: this video. And at WCeLfest, we watched it together.

As you’ll have seen, there are a few, very basic, questions at the end of the video, but we stopped the video before reaching the quiz & instead briefly discussed and answered each question in groups, plus there were some additional queries, which was great. The original set of questions reinforce the basic concepts & give those students who were unfamiliar with them a bit of confidence that they’re prepared for the next step.

Now, for my ‘real’ class I’ll be showing an additional, more complex video, but for this shorter session we just moved on to the data interpretation.

Again, I explained the rationale behind this part of the session. I’d decided to do this exercise with my first-year students for a couple of reasons: firstly, to break up the class and get them actively engaged in the learning process; and secondly, to give practice in the process skills needed to interpret information provided in graphical form. The question they needed to address, using their knowledge from the video and the data in the graph, was: without plants, life as we know it wouldn’t have evolved in the first place. Why not?

O2 concn over time.png

As I do in my normal classes, while the class split into groups to come up with an answer, I circulated between those groups2 in order to hear what was going on & field any additional questions. “What was the atmosphere made of before photosynthesis began?” was one, which led to a brief consideration of how the Earth formed. And I needed to explain oxidised/oxidation, as well. This was a really valuable process for me as it’s highlighted a couple of areas where I need to do a little more background work with my first-years.

A quick summary of the class discussion: the ‘oxidation’ part is important because that’s how we know when oxygen generation began – iron-rich rocks began to rust. It wasn’t until the exposed rocks had been oxidised and the ocean had become saturated with oxygen, that oxygen began to be released into the atmosphere, as evidenced by more oxidised rock. As O2 accumulated in the atmosphere, the ozone layer formed, offering protection from the sun’s UV radiation & allowing living things to move onto the land.

And we finished with a quick look at the ‘design-an-organism’ class that I’ve previously blogged about.

The feedback was very positive, with several people saying that they could see how they might use the flipped classroom technique in their own teaching. It was also lovely to hear someone say that they’d got a bit worried when they realised we’d be talking science, but that they’d really enjoyed the experience and learned some new things along the way. And I’d learned ways to improve the exercise, so the enjoyment & learning were mutual


1 These are AS91155 Demonstrate understanding of adaptation of plants or animals to their way of life, and AS91156 Demonstrate understanding of life processes at the cellular level. You’ll find them here on the NZQA website.

2 In my ideal class3 there’d be an ‘aisle’ between every 2 rows of seating, to allow teachers/facilitators to move more freely among the students.

3 I can dream, can’t I?



"the only memory of the bee is a painting by a dying flower" Alison Campbell Sep 09

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The image below is of the bee orchid, Ophrys apifera. I know I’m ‘seeing’ something – the ‘face’ – that isn’t really there (an example of pareidolia), but still, that’s one happy-looking flower!

File:Ophrys apifera (flower).jpg

Image courtesy of Hans Hillewaert, from wikimedia.

Actually, the flower looks quite a bit like a bee sitting on on a blossom. This suggests that the plant is pollinated by at least one species of bee, with male bees attempting to copulate with something that looks to them like a potential mate. This is well-known in orchids, and indeed some species also produce pheromones mimicking those of a female wasp.

However, it turns out that over much of the range of O.apifera there is no longer any pollinator. Instead, in many regions the orchid self-pollinates, relying on the wind to blow the flowers dangling pollen sacs (‘pollinia’) against its sticky stigma, which seems a little hit-&-miss.

While one pollinator does still exist in one part of the orchid’s range, this cartoon from xkcd is nonetheless rather poignant:

Bee Orchid



moss s*x and springtails Alison Campbell Jul 22

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Sexual reproduction in flowering plants is often mediated by the birds & the bees (& other animal agents), but up until now the life cycle has appeared much simpler in plants like the mosses. Until fairly recently it was generally accepted that moss sex was a case of ‘just add water’: this released sperm from the male plants which could then swim in the film of water to where the female plants held their eggs. Of necessity this would mean that sperm dispersal could be only over quite short distances, of a few centimetres at most.

However, Todd Rosensteil and his colleagues (2012) decided to confirm the hypothesis that arthropods known as springtails could be involved in transferring sperm between male and female mosses. (Springtails and mosses evolved at the same time, during the Ordovician period.) They posed a number of questions: were springtails really acting as go-betweens in moss sex? If the answer was ‘yes’, how did the moss plants attract their little helpers? And, were the springtails important only if there was not much water around?

Using a common – & cosmopolitan – moss called Ceratodon purpureus, Rosenstiel and his colleagues first determined that female C.purpureus plants emit a significantly greater number of volatile organic chemicals (VOCs), which could act as signals to springtails, than male mosses do. They then carried out a number of experiments.

First of all, they gave springtails a choice between male and female moss plants – the tiny arthropods were much more likely to go for the female plants. (However, it’s not yet clear why the springtails respond positively to this signal: do they get some sort of a food reward?) The same was true when the springtails were given no visual cues & were simply offered a choice between male and female moss VOC samples.

Then, they set up a series of ‘microcosms’ – miniature ecosystems containing moss plants, and where the presence of water and springtails could be manipulated. This time the research team used both C.purpureus and another moss species, Bryum argenteum, in which earlier work had shown that springtails were implicated in spreading sperm around. Some of their microcosms had only the mosses. Others were sprayed with water but had no springtails, or had springtails but no water spray. And some had both springtails and water. The results were fascinating.

When a female moss plant’s egg is fertilised, the resultant zygote grows into a thin brown stalk with a capsule of spores on top: this structure is called a sporophyte. Unsurprisingly, mosses in the absence of both water and springtails produced very few sporophytes indeed. Both the ‘springtail treatment’ and spraying the mosses with water caused a marked increase in fertilisation, as measured by the number of sporophytes produced. But combining springtails and the water treatment saw the number of sporophytes more than double, compared to each treatment on its own. The researchers commented that

[t]hese results highlight the substantial role of microarthropods in facilitating fertilisation in mosses, presumably through enhanced sperm transport.

So maybe we really are looking at something akin to the relationship between flowering plants and their pollinators. And, given the potential antiquity of this arrangement,

it is important to consider the potential role that a plant-pollinator-like relationship may have had in shaping the evolutionary ecology of moss mating systems.

I will definitely be changing the ‘additional reading’ list for my first-years!


T.N.Rosenstiel, E.E.Shortlidge, A.N.Melnychenko, J.F.Pankow & S.M. Eppley (2012) Sex-specific volatile compounts influence microarthropod-mediated fertilisation of moss. Nature published on-line 18 July 2012, doi: 10.1038/nature11330

first supertrees – now super domes Alison Campbell Jul 19


singapore conservatory dome.jpgAfter goggling (a mixture of gobsmacked & ogling) the supertrees, our little party of escapees from the day’s official IBO program made our way into the Flower Dome, the first of the two great conservatories in Singapore’s Gardens in the Bay. Cue more ‘oh, wow!’ moments as the scale of the building became apparent – this is what it looks like once you’re through the doors (& into the wondrous coolness of the huge space):

singapore - entrance to flower dome.jpg

This dome contains gardens, or garden collections, from around the world, including the displays of flowers that give it its name. I was fascinated by the visual juxtaposition of the gardens with the almost futuristic cityscape beyond the conservatory walls.

singapore - flower dome & cityscape.jpg

singapore - flower dome hibiscus.jpg

From some perspectives the dome’s interior gives the impression of being heavily forested, & it’s at this point I had to keep reminding myself that none of this was here even 4 years ago: all the mature trees were brought onto the site from elsewhere…

singapore - flower dome forest look.jpg

… including a 1000-year-old olive tree. We could only guess at the huge amount of work (by goodness knows how many gardeners) to get all these plants established.

singapore - flower dome with olive tree.jpg

There’s also a wonderful collection of xerophytes: plants adapted to life in a dry environment. The plants in the following photo show a range of interesting adaptations related to this lifestyle.

singapore - xerophytes.jpgAnd scattered through the dome is a range of artwork, including this lovely botanically-based eagle, developed from the roots of a tree. (I am always amazed at how some people are able to ‘see’ the form within something, and work to bring it forth.)

singapore - flower dome eagle.jpg


in the lecture theatre – but definitely not giving a lecture! Alison Campbell Apr 02


This is a post I first wrote for Talking Teaching – but hey! it’s about teaching science!

Today’s class was a real experiment for me, & although I try lots of different things in my classes, it was also a step outside my normal comfort zone. (But hey! life would be a bit boring if we always stayed safely inside that zone!) Why? Because I put into practice an idea I stole from my friend & colleague Kevin Gould (who also very kindly let me use the resources he’d developed): today was “design-a-plant” day, & probably to anyone looking into the lecture theatre during the first 30 minutes or so it would have looked as if chaos definitely ruled.

Last Friday I gave everyone an information sheet: descriptions of the features of leaf, stem & root that you might see in plants adapted to different environments. Today I trotted off to the lecture room with a box full of overhead transparency sheets, overhead pens, & printed scenarios (descriptions of a particular environment). The lecture theatre was already full — everyone had come ahead of time! This definitely wasn’t usual (it’s not that they normally trickle in late, but we’re talking seriouslyearly); obviously they were expecting something special. Gulp.

So I put up these slides:

then once they’d sorted out their groups I dished out pens, transparencies, scenario sheets (& copies of the info sheet for those who’d forgotten them), & away we went on a mutual journey of discovery. After all, this wasn’t myidea & I had no idea how it would really work out.

Well! The class erupted into happy, productive noise. I know it was productive because while they talked, argued, explained & persuaded, I circulated, listened in, & answered the occasional question. Those with computers had them open – looking up information related to their scenario. (Next time someone asks a question that I can’t answer on the spot, I’m jolly well going to get someone else to google it for me!) They drew, & altered their drawings, & drew some more. The original 20 minutes stretched towards 30, & still they were focused on what they were doing. I was almost sorry to interrupt :-)

Then, I called for volunteers. A hand went up almost immediately, & its owner came down to the overhead projector, not looking too nervous. She picked up the microphone, described her group’s scenario, & showed – & explained – their response. The next speakers followed just as quickly, and each speaker received a round of applause as they finished.

But the proof’s in the pudding – just what sort of plant had they designed? Well, they didn’t necessarily look like plants that my botanical colleagues could have put a name to, but nonetheless, the explanations each group gave for their particular design were sound, & science-based. They’d obviously taken on board not only the info on that fact sheet, but also the material we’d been looking at in lectures & that they’d found on line. And they’d had fun doing it. (I particularly liked the Nepalese Death Vine – the eerie noise of the wind passing through its herbivore-deterring spines apparently puts the locals off harvesting it, lol – and the Serengeti “cactus” that traps water in basin-like leaves, but when there’s a fire the plant’s transpirative water loss is such that its tissues become flaccid and it wilts, spilling that water onto the ground where the dampness keeps the worst of the fire at bay.) Plus – so far, the feedback for this exercise on our Moodle page is all positive: students felt it definitely helped their learning about plants.

Thanks, Kevin — your design-a-plant lesson got an A+ from all of us today!

skulls & braaiiinz – what’s not to like? (also, plants) Alison Campbell Jan 03

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The intrepid reporters from Number 8 Network e-mailed the other day. “What are you reading?” they asked; “after all, it’s the holidays & you must have heaps of time to put your nose in a book.” Which is sort of right, it is the Christmas/New Year break, but the days just seem to fly by when you’re doing not very much at all.

However, as it happens I’m working my way through several books at the moment, so I was able to oblige.

First up is Skulls, by Simon Winchester. Strictly speaking it’s not actually a book but an interactive iPad app, based on the enormous personal collection of Alan Dudley. I bought it because I find skulls fascinating (though not so obsessively fascinating as I think they must be for a collector of same) & the blurb at the app store offered me the ability to zoom in, out & around a whole bunch of bony brain protectors. This, I figured, would be quite fun & could also be a useful teaching tool (I’m looking forward to showing it to a colleague who teaches 3rd-year zoology).

And the ability to examine skulls in such detail really is great, although – a minor quibble! – I would have liked to be able to look at them from beneath & above as well as from all sides. You lose some definition at high levels of zoom but apart from that, wow! I would otherwise not have known that the Atlantic wolffish has quite so many teeth (shades of an aquatic Red Riding Hood villain) & such a wonderfully architectural skull. Or that a rabbit could somehow have lived long enough for its incisors to grow backwards & inwards in curves reminiscent of reversed (& miniature) elephant tusks.

The chapters comprising the ‘book’ struck me as a bit of an eclectic mix: we’ve got an interview with the collector himself, followed by an essay on the nature of collecting. Then, after learning about what a skull actually is & the bones that make it up, we find out about the dodo, or the pseudoscience relating to skulls – wherein we can learn about Piltdown man & phrenology but not, to my surprise, the various claims about ‘alien skulls’ from South America. Or the iconography of skulls, or skulls in art & in Mexico, & so on. One of the nice things about apps like this is that – even less than with a ‘real’ book – you don’t have to follow a linear progression through the text but can dip in & out, & that there are nice little visual cues to guide you in your choice of where to go next.

Not a lot in the text that was completely new to me, but well worth the price (at $17.99 this is one of the more expensive iPad apps) for the sheer enjoyment to be gained from viewing the images.

As for the brains – I’m also working my way through a Kindle edition of Carl Zimmer’s Brain Cuttings. Zimmer is one of my favourite science writers & this collection of essays (mostly written originally for Discover magazine) hasn’t disappointed me. The first essay’s title is from a question asked by Charles Darwin of one of his many correspondents. Wondering whether people around the world expressed emotions in the same way, Darwin asked, “Does shame excite a blush?” From this starting point, Zimmer takes us through scientists’ current understanding of the evolution of the face, a feature that began to form around half a billion years ago with the appearance of the earliest fishes. He asks why primates, in particular, have such complex, expressive faces – something that has to do with the complex social behaviour of this group of mammals. It turns out that facial mimicry is part of that social behaviour – and apparently the ability to mimic someone else’s facial expression, however briefly, may well be important in allowing us to understand how that person is feeling. An interesting experiment certainly suggests this:

[Researchers] had volunteers bite down on a pen and then look at a series of faces. They had to pick the emotion they thought the faces were expressing. The volunteers could recognise sad faces and angry ones with teh same accuracy as test subjects who did not have pens in their mouths. But they did a worse job of recognising happy faces.

Biting a pen, it just so happens, requires you to use the same muscles you use to smile. Because the smiling muscles were active throughout the experiment, [the research] subjects apparently couldn’t reel themselves start to mimic happy faces. Without that feedback, they had a more difficult time recognising when people were happy.

And that’s just the first chapter! The second essay, “The googled mind”, is an exploration of just where the mind stops. As Zimmer remarks,

[we] tend to think of the mind as separated from the world. We imagine information trickling into our senses and reaching our isolated minds, which then turn that information into a detailed picture of reality… In fact, teh mind appears to be adapted for reaching out from our heads and making the world, including our machines, an extension of itself.

In other words, it looks like the ‘mind’ is more of a complex system that comprises both the brain and various bits of its environment – books, for example, or computers, iPads – and even the tools we use.

This book’s both entertaining & informative & I’m enjoying reading it, one chapter at a time.

Third on my list is an actual, print-on-paper, hardcopy book: Fifty plants that changed the course of history, by Bill Laws. I bought this on a colleague’s recommendation, because of all the topics I teach at first-year level, botany seems to be the one that students are least engaged with, & I was hoping for some nice new examples to add my list of ‘cool stuff about plants & how they changed our world’.

My impression of this book is that it’s a bit like the curate’s egg: good in parts. My copy is a beautifully presented hard-cover edition, with lovely illustrations & some fascinating snippets of information (for example, that pineapples were grown in England over pits full of fresh dung! (This generated heat as it rotted, & augmented the warmth from stoves.) And the idea of a bamboo bicycle is an intriguing one. I’m enjoying dipping into it, a couple of plants an evening.

But unfortunately that enjoyment is tempered by moments of irritation. OK, I know I’m simply being greedy in wanting to know more about some topics than can be fitted into the 2 or 3 pages accorded them here. That’s a minor one. But saying that plants “absorb carbon dioxide and exhale oxygen” glosses over the fact that plants need that oxygen for cellular respiration as much as we do. (All too many of my first-years share this particular misconception.) And what am I to make of the following statement ?

The oldest names for the coconut are in Sanskrit, pointing to India as the source [of this plant]. However, the discovery of the fossilised remains of a tiny proto-coconut on New Zealand’s North Island suggests it might have been first taken into service here 5,000 years ago.

Five thousand years ago, there weren’t any people in New Zealand; hence no-one to take anything ‘into service’… (Interestingly, Sir Charles Fleming notes that a fossil coconut dating to the middle-late Miocene was discovered in Hawkes Bay; this would give an age of around 5-10 million years.)

So, I’m accumulating some new stories to tell in class, and I am enjoying the read, but – unlike Skulls and Brain Cuttings – I probably won’t be recommending Laws’ book to students looking for a bit of extra reading. At least, not until I’ve finished it & identified any other potential pitfalls. Although… I guess the error I’ve picked up on here would be a useful jumping-off point for a discussion of New Zealand’s botanical history.

B.Laws (2010) Fifty plants that changed the course of history. Firefly Books. ISBN: 978-1-742372-18-1

S. Winchester (2011) Skulls. Touch Press.

C.Zimmer (2010) Brain Cuttings: fifteen journeys through the mind. Scott & Nix Inc. NY ISBN (Kindle): 978-1-935622-16-1

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