botanizing

Learning museum display design

The students in my museum course worked last week with Kathleen Ryan, a faculty member in the Department of Interior Design at our university.  Kathleen worked as a museum exhibit designer before taking a faculty position at the university.  In one class last week, she showed students examples of exhibits she had designed and talked about design concerns for exhibits.  In the second class, she had the students in a studio to practice an exercise in display design.

In the studio, the students were given photographs of displays from the Conner Museum and tracing paper.  Kathleen asked the students to trace one or more the elements of the current displays as the basis for a redesigned displayed.   Kathleen wanted the students to understand how to tell a story with a few objects and minimal text.   The students pondered for a few minutes the themes for their display designs.  They outlined possible ideas, considering display titles, subheadings and the kinds of descriptive text that might be used.  Then they jumped into what Kathleen really wanted, which was simply to sketch a composition that included objects and text blocks while considering how a visitor would interact with the display.  At the end of the exercise, Kathleen had the students talk to each other about their display designs.

As part of the course expectations, the students will now begin a display design project. I’ve told them the size of the wall space or case that the display needs to fit and given a few other basic instructions.  Over the next few weeks, each student will design a display with a theme and objects of his/her choice. They will sketch a design that incorporates objects and text for a hypothetical display.  In early March, we will discuss the designs they have made.

I’ve been thinking about a display I may design.  Several years ago, I wrote here about a museum I imagined that would be devoted to rivers.  I envisioned this museum holding collections of rivers in Mason jars.  And now I’m thinking of designing my first display for that imagined museum.  I need to find some Mason jars to sketch.

Syllabus progress

Rather slowly and gradually, I have been assembling the syllabus for my spring course on museums.  Through the fall and early winter, I read essays and books about museums to search for material to use in the course.  The readings are now mostly selected, but I debate with myself about the choices.  Some readings, such as the choice of an article from The New York Times on the conservation of Spiral Jetty, which I will use to begin the course, make me very happy.  I like the quirkiness of beginning a course on museums with an article about art made from stones that lies in a lake (albeit an receding lake).  The short, simple article raises questions about what constitutes a museum, the roles of curators, choices of conservation, and the significance of objects (especially how museums create significance) that will be an excellent way to introduce important ideas for the course. 

We’ll also be reading chapters from Susan Pearce’s Museums, Objects and Collections, which I find clear and interesting.  I like Pearce’s logic and organization, but I’m concerned the students will not be engaged by her.  A dilemma debated in my head is whether I should use articles that are logical, well organized, and informative (and likely not to engage the students) or those that are more pointed, outlandish, and less informative (but more likely to rouse and hold the students’ interest).  I am opting mostly for the informative, which is a weakness of mine.  I will need to bring examples and thoughts into the discussions to keep them lively.

Among the most engaging of readings for the course is a long selection from Edward Linenthal’s Preserving Memory, which is about the development of America’s Holocaust Museum.  His discussion of the development of the exhibits, how the architecture of the building shaped exhibit decision-making, how stories were to be told using materials, and especially how exhibit design emerged from both creativity and compromise, is marvelous as well as poignant.  Linenthal’s book provides one of the best examples of how museums operate to tell stories, create perspective, and maintain memory.

Among the lighter pieces in our readings will be a chapter from William King’s Collections of Nothing—the story of one man’s obsessive collecting that raises good points about how much of the material in museums was originally assembled.  There are also essays on museum architecture, virtual collections, and the Parthenon Marbles that I think will be good reading for grand discussions.

This afternoon my work on the syllabus turned to expectations for the course.  This is always difficult.  What must students do and what must they achieve to get grades, especially good grades in a course.  Unlike my classes on plant science, I will not give exams in this course.  I will have the students write and create.

The plan—at least at the time I left my office at 5.30—was to have the students write 12 brief essays of 300-500 words that address ideas, the readings, and the museum visits in the course.  I plan to have the students construct weblogs, on which they will post their essays.  I like this approach because I think it helps students recognize that they are writing not just for me but also for a broader audience.  I will expect the students to comment on each other’s essays.

There will also be two projects in the course.  In the first half of the course, the students will design museum displays, and they will present their designs at the last class before the midterm break.  In the second half of the course they will have a larger project that I will expect each student to design in consultation with me.  For these larger projects, I anticipate encouraging gallery redesigns, developing exhibits, developing virtual displays, creating educational programs, formulating fund-raising or marketing strategies, or other projects that are centered in campus museums to give students practical experiences.

At least that’s what I was thinking today.

A new course

Last week I watched student registration numbers for spring semester.  I wondered whether anyone would sign-up for my course.  My course for spring semester is new, and I had advertised it fairly little, posting large fliers near museums on campus and having the flier sent to departmental advising contacts.  As I checked online, I saw the first student and then a few more register for the course.  A minimum enrollment threshold must be met for an undergraduate course to be taught—I’m unsure of the exact threshold number, perhaps ten or 12—and I wondered whether the new course would reach the minimum.  

I’m teaching the new course as an overload—it’s work I’ve volunteered to do over and beyond my standard teaching load.  Volunteering for extra teaching is not the wisest choice in a research university, where administrators clearly value faculty more for the money they bring to campus in research grants than for teaching.  I chose to teach the new course as part of my role as interim director of the university’s Conner Museum of Natural History.  I have long been director of the university’s Ownbey Herbarium, which functions as a research museum, but the new role, leading the Conner Museum, includes responsibility for a public exhibit and broadens my outreach work.  I see the new course as part of my outreach effort.  

The new course, called simply Museums, will allow me to introduce students to the world of museums.  Despite the demands and extra workload of a new course, I enjoy creating them.  Creating a new course is a little like preparing to write a book or designing a large research project.  It has many dimensions, and one must decide where to focus.  The title—Museums—gives the course its theme, but it will be shaped by two questions:  How do we explain museums?  &  How do we explore museums?  When teaching, I want to cultivate in students senses for explanation and exploration.  The later especially is important for students need to gain the expertise to explore effectively on their own.  Exploring is something different here than wandering the galleries of a museum, although that wandering will certainly be part of the exploration.  To explore, one must know how to examine while applying perspective to interpret and think creatively.  While using perspective, exploration is a process that also enhances, broadening and sharpening, one’s perspective.

The new course will examine what has been called ‘museum studies’ or ‘museology,’ an awkwardly musical term that seems initially to be a little frightening.  When I first started to think about the course several months ago, I downloaded syllabi for museum studies courses that had been posted on the Web.  I was curious to see how others had constructed courses on museums, what topics they included, what readings were assigned, and what projects the students conducted.  Next I ordered a large pile of books and checked-out others from the library to begin my background reading, expanding my knowledge beyond the practical experience I’ve gained from directing university museums and hanging-out in others.  Slowly, I have been reading the books and essays on museums, making notes, and gathering syllabus ideas.  I’ve also been acquiring new ideas that I want to put into practice in the museums that I direct.

I had not wanted to invest too much time in the possible new course until I knew that the enrollment number met the minimum threshold.  This past week I began to draft a syllabus for the course, selecting readings and designing student projects, when the registration for the course had reached 15 students.

Midterm exam

On Monday of this week I gave the first midterm of the semester for my introduction to botany course.  Midterm time is always a bit tense.  In the last half of last week, I was searching for time to write the exam amid many other commitments.  The exams in this introductory course, in which there are nearly 100 students, use multiple-choice questions, which are time-consuming to create.  I knew I was short of time when I started the exam, and this led me to do something I have not done in the past.

I have always in the past started to write my exams with a fresh sheet of paper.  For each lecture, I would write roughly the same number of questions, and I have always written entirely original questions my exams.  Last week, I took an exam from the last time that I taught the class, and simply rewrote most of the old questions.  This rewriting was extensive—I restructured the point of the question and wrote entirely different answers for the multiple choices, but this approach meant I didn’t spend time thinking about question topics.  Of course, the main topics of the lectures remain the same from year to year despite the bits of new information and different ways of explaining material that are added each year.

By last Sunday morning, I had finished writing the exam and made two forms of it.  The forms have the same questions but in different orders to limit opportunities for students to copy from neighbors in the tightly packed classroom.  I photocopied one form on pink paper and the other on blue.

After I photocopied the exams, I went off to a review session that I had scheduled for the students on Sunday afternoon.  There were about 15 students at the review, and I spent an hour and a half answering their questions.  This small group of students seemed relatively ready for the exam.

The exam went smoothly on Monday morning, although I noticed that students who had blue exams tended to finish more quickly than students who had pink exams.  This had to be one of those odd, random events because the two exams forms were identical except for the order of questions.  But it was odd.  And then, when the scores for the exam were returned from the processing facility (the Deus ex Machina of grades), the mean on the pink exam was three points lower than the mean on the blue exam.  I checked for errors on my key but couldn’t find any.  And I began to think that my pink exam was prone to quirkiness.

The mean on the exam was 68 points out of 100 possible.  The mean was respectable, and I felt it was a successful test, covering broadly the content of the material we had studied and providing student scores that ranged from the low 30s to 94 points.  [O.k., I admit that I am always discouraged that all of my students don’t do exceptionally well on exams.  I really want to believe the lectures are excellent, and that the students are fully engaged and wanting to learn. In the real classroom, both lectures and students are compromises.] When I discussed the exam with the students in lecture on Wednesday, there were a few grimaces and a few hard stares, but otherwise everyone seemed to be relatively content with the test and scores.  One student did suggest that one of my questions was vague.  Surely not, I was thinking . . . and thinking also that they were concerned only [ONLY!] about one question.

Now we move forward with more material—new labs this week and new lecture material.  And my diligent students, who are thirsty for knowledge. . . half of them skipped class yesterday, a lovely Friday.

*  *  *

Here are ten questions from the exam for your test-taking pleasure:

1. The formation of haploid cells from a diploid cell results from:

A.  Recombination.
B.  Meiosis.
C.  Syngamy.
D.  Spores.


2. In autumn, the abscission process that separates leaves from the main part of the plant body involves:

A.  Perforation of cell walls.
B.  Formation of secondary cell walls that seal the leaf from the movement of nutrients.
C.  Breakage of cellulose microfibrils.
D.  Breakdown of pectin in middle lamella.


3. Which of the following is true of plant sporophytes?

A.  The sporophyte makes sporocytes that undergo meiosis to make spores for dispersal.
B.  The sporophyte phase is limited only to the diploid zygote, which undergoes meiosis.
C.  The sporophyte makes gametangia in which gametes are formed after cells undergo meiosis.
D.  The sporophyte is a result of asexual reproduction that involves fragmentation of the plant body.


4. The main constituent of primary cell walls of plants is:

A.  Cellulose.
B.  Lignin.
C.  Pectin.
D.  Protein.


5. Where would you expect to find cells that have secondary cell walls?

A.  Around the photosynthetic cells of leaves.
B.  In the abscission zones of leaves.
C.  In cells that function in providing rigid support, such as those of tree trunks.
D.  In all eukaryotic cells but not in prokaryotic cells.


6. In the life cycle of plants, zygotes result from:

A.  Plasmolysis of gametes.
B.  Syngamy of gametes.
C.  Daughter cells of mitotic cell divisions.
D.  Daughter cells of meiotic cell divisions.
 

7. In autumn, leaves change color in some trees from green to yellow or orange because:

A.  Chlorophyll degrades to reveal anthocyanin pigments in cell vacuoles.
B.  Chlorophyll degrades to reveal carotenoid pigments in chloroplasts.
C.  Chloroplasts begin to form carotenoids rather than chlorophyll.
D.  Nitrogenous compounds in leaves begin to glow red when they are absorbed back into the plant body from the dying leaves.


8.  The energy that drives the light reactions of photosynthesis is obtained from:

A.  Electrons.
B.  Sunlight.
C.  ATP.
D.  Sugar molecules.


9.  Plant cells are turgid when:

A.  Cellulose microfibrils in the cell wall are locked in place by keytanes.
B.  An equilibrium of water movement into and out of a cell is achieved.
C.  Secondary cell wall formation prevents cell expansion.
D.  Osmosis causes the entry of water into the cell and the protoplast pushes outward against the cell wall.


10. The volume of mature plant cells consists largely of which of the following?

A.  Vacuole.
B.  Nucleus.

C.  Chloroplast.

D.  Cell wall.

*  *  *

The answers are: 1B, 2D, 3A, 4A, 5C, 6B, 7B, 8B, 9D, 10A.

Missteps to End the University?

On the Op-Ed page of The New York Times, Mark C. Taylor, has called for the end of the university as we know it largely because he is displeased with PhD programs.  He claims that the “dirty secret of higher education is that without underpaid graduate students to help in laboratories and teaching, universities couldn’t conduct research or even instruct their growing undergraduate populations.”

In serving my department on the committee to select prospective graduate students, we certainly recognize that students are accepted in part to help teach courses.  State research universities, as they are currently configured, could not enroll the high numbers of undergraduates they have without the assistance of either graduate students or instructors in teaching, given the expectation of a high level of faculty research productivity and fund-raising for research.  In addition to innovative research, state research universities provide relatively inexpensive education as well as broad opportunities for undergraduates.  These universities serve their states well in educating the population and, as state populations grow and more diverse facets of the population seek the opportunities of education, pressures to enroll high numbers of students are likely to continue.

While Professor Taylor calls for an end to the university as we know it, he fails to provide a new model to address how enrollment pressures will be handled.  Do we abandon the large, research university model and leave thousands of students without educational opportunities?  Do we tell these abandoned students to go to smaller private schools where they will be paying 20 to 30 times as much for their education?

Taylor claims that we encourage students to enroll in doctoral programs under “the illusory promise of faculty appointments.”  In my time as a university faculty member and a mentor for doctoral students, I don’t recall ever promising any student that a faculty position would be waiting when he or she completed a Ph.D.; indeed, I have discussed with doctoral students the difficulties of finding and the stresses of having university faculty positions.  Many students may apply to PhD programs because they are enamored with an image of academic ‘life.’  Most applicants to PhD programs may want to be professors and many want especially to teach in a college (because they don’t want to teach in the horrors of our K-12 education), but they also tend to be students who are very curious and are drawn to the opportunity to explore.  Despite Professor Taylor’s claim that faculty appointments are illusory, most of the students who finish PhDs in our biology program succeed in landing faculty jobs in colleges or universities.

The illusions may belong to Professor Taylor, who seems to believe that a PhD is a means to a faculty position and nothing else. In training PhD students, I have never thought the objective was to provide them with faculty jobs in universities.  The objectives are to develop their investigative, reasoning, and reporting skills.  I like to think that a student takes the skills that he or she develops as a graduate student to apply them in creative, interesting ways in life and society.  Those opportunities might lie in a university but they could also lie in some other venue.

What is meant by Professor Taylor’s call for universities to “expand the range of professional opportunities for graduate students”?  Professional opportunities lie not narrowly in universities but broadly in society. A PhD in the sciences can offer many job opportunities, although if breadth of opportunities is the goal, then I would never encourage anyone to seek a PhD. There are not vast numbers of jobs outside of academia that require a PhD, but getting the degree may enhance skills that can be applied exceptionally well in various jobs.  Doctoral programs develop skills that are applied in journalism, industrial research, biotechnology, and in resource management.

Let me suggest to Dr. Taylor that students choose to work toward a PhD because they want the degree and the research/scholarship experience, not because they were seduced by illusions of a professorship.  We can, however, learn from Professor Taylor’s critique and suggest that universities emphasize to prospective PhD students that doctoral study is a means to develop skills and not automatically the final step into the professorate.

Another of the changes requested by Professor Taylor is the transformation of the traditional dissertation. His concerns apply especially to graduate programs in the arts and humanities, in which dissertations are ‘books.’  In the sciences, the tradition of the dissertation has changed over time.  Dissertations in the biological sciences, for example, consist of studies that are prepared for publication in scientific journals.  Each of the studies of a dissertation addresses specific questions and consists of distinctive sets of experiments, with details of design, hypotheses, results, and discussion.  Dissertations in the biological sciences are largely ready for dissemination to the scientific community (and to any others who wish to read research journals) when a student finishes his or her doctoral study.

We should be cautious, I think, about accepting Professor Taylor’s assertion that a “traditional dissertation” exists.  Dissertations differ among scholarly disciplines, and they have been changing over time.  Calling for the transformation of the dissertation, as Taylor has done, leaves much to be addressed.  We need to ask what will replace the dissertation and how universities will determine whether the ‘new dissertation’ meets criteria for scholarship and demonstration of intellectual accomplishment. 

Professor Taylor wants to dissolve tenure and turn academic appointments into seven year terms.  He offers these proposals as means to reward those who continue “to evolve and remain productive while also making room for young people with new ideas and skills.”  Tenure has been a means of distributing power and allowing many voices to be heard in universities (and society).  Abolishing tenure will shift more power into the hands of a few administrators, such as department chairs like Professor Taylor.  It will also serve to silence dissenting voices—those who might have the most creative ideas and those who might disrupt the gross group-think of administrators and politicians.

Although a few tenured faculty become ‘nonproductive,’ I suspect this is uncommon.  Most of the senior faculty I’ve known at research universities have been productive throughout their careers.  Indeed, a majority may continue to produce new research into the early years of retirement.  An advantage of tenure is that it allows a faculty member to attempt less secure avenues of research.  When the security of one’s job does not depend on every study producing positive results and easy publications, a researcher can explore less conventional ideas and design more difficult projects.  These may be exactly the kinds of projects that we want to have centered in universities because they will be unlikely in industrial settings.


Faculty at Professor Taylor’s model university would not be centered in departments; instead, they would be part of “constantly evolving programs.”  It’s unclear who would choose these programs and what selective forces would cause their evolution.  In the absence of tenure, we can assume that the faculty would be beholden to department chairs and deans, and it is likely to be a small set of these kinds of administrators who would select the programs and force their evolution.  One can easily envision Professor Taylor’s university in the control of an elite few, whose favoritism would be curried.

As an example, an administrator at our university recently told my department we didn’t bring in sufficient funds from our research grants.  Although we have more grants than comparable departments within our university, our grants are worth less.  Our administrator suggested that we should consider making future hires in disciplines that provided more lucrative grants, such as those from the National Institutes of Health.  Here was a clear case of an administrator trying to evolve our program toward greater fund raising, which would increase the overhead dollars available to manage the college and the university, but it would mean shifting the focus of our biology department away from the disciplines of ecology and evolutionary biology in which we have strengths.  The research in our department on invasive species, crashing amphibian populations, effects of climate change, genetic diversity of rare organisms, and many other areas may be quite important to provide the knowledge necessary to manage resources and conserve the Earth, but it does not result in the large federal research grants that provide the overhead funds that university administrators want for their programs.  In the absence of tenure, administrators will be able to “evolve” programs to maximize funding objectives, but those administrators might not have broad enough vision to design programs or retain faculty that help us to manage resources and conserve humanity.

While Professor Taylor’s call to end the university as we know it is provocative, it is not clear that his model will create either a better educational environment or result in better research to address social and environmental problems.  The six major steps that he proposes in his Op-Ed essay could be dangerous missteps.

Course planning

At 4.30 this morning, I woke sharply and tensely.  The needs of my fall semester course reeled through my mind.  Classes start in a month.

I’ll teach this fall introduction to botany.  It’s a course that serves our general education curriculum, which means that it can be taken by anyone, regardless of his or her science coursework background, to fulfill university science requirements.  About half of the students who enroll have never had a biology course, and many these students are apprehensive, if not fearful, about science.  It’s an opportunity to talk genially about material I thoroughly enjoy and to indulge in metaphors and stories to teach a few basic ideas about plants.

I plan to revise completely my lectures and with a colleague, with whom I alternate teaching the course every other year, I am revising the laboratories.  The old laboratory manual hasn’t been working well for the students.   We will create new laboratory exercises that emphasize investigation and experimentation.  And I will prepare new lectures centered on about dozen concepts, and, of course, I’ll prepare the lectures in Powerpoint. 

A year ago, I revised my plant diversity course to apply Powerpoint.  Each of the 75-minute lectures for that course took about 18 hours to prepare.  My three lectures per week this coming fall semester will each be 50 minutes, requiring, I expect, about 12 hours of preparation per lecture.  That 12 hours of preparation, although difficult to think about in the middle of the summer, has been typical for all of the new lectures I’ve prepared for courses over the years.

With tea and toasted bagel at hand this morning at 5.00 a.m., I was drafting notes for laboratories.  For a couple of laboratories, I wrote first the concepts to address and then sketched out possible exercises and materials we could use.

I walked to campus about 8.00 and pulled-out my lectures and syllabus from the last time I taught the course.  Although I’m scheduled to teach this course every other year, because of the timing of my recent sabbatical leave, I last taught it four years ago.  As I sorted through the old lectures, I wondered what could be scavenged to fit the new objectives and format for the course.  I wondered also how to sequence of course concepts and how they would fit with the laboratories.

I turned-on my computer, opened Word, and listed my lecture dates.  I blocked-out the concepts, largely giving one concept to each of the fifteen weeks of the semester, and tried to fit laboratory topics as closely as possible to the lecture material.  It’s all so simple, so natural.  Then I revised everything, adjusting the sequence, dividing a few themes, and I added some material on plant conservation and flora of the Pacific Northwest that I haven’t used before.  I began to admire the schedule and held it at arm’s reach to get a good look – that’s when I recognized that no exams had been scheduled.  I added the tests.

At the end of the afternoon, I typed ‘Syllabus’ in bold at the head of the lecture schedule.  All I need to do now is write the lectures and laboratories.

A final lecture

It was twenty years ago that I wrote my first university course.  I’ve created several courses since then, but I don’t remember any that were as all-consuming as the revision of my plant diversity course has been this semester.  For the lecture I gave this morning, I began writing over the weekend.  It was a largely easy lecture to compose on the structure and diversity of flowers, a topic that I know well since it has been a major theme in my research.  In a couple of stretches on Saturday and Sunday, I composed the text for the Powerpoint slides.  It was on Monday morning that I began scavenging images from the Web and sorting through books and papers for additional images that I wanted to scan, but this work was tucked around several meetings and visits by students during the day.  When I looked out to the dark and snow at 4.30 in the afternoon, the lecture was far from completed and various materials still needed to be scanned.  I stuffed the papers to scan and my laptop in my bag to head for home, where a scanner was more convenient. I scanned at home, ran images through Photoshop, while also continuing to search the Web for things to use, and then pieced these pictures into the story on the Powerpoint slides.  By 10.00 p.m., I was worn for the day and went to bed without a finished lecture.  Fortunately, with only another couple of hours of work this morning, everything was in place for the lecture before class.

Tomorrow morning I’ll start the lecture for Thursday’s class.  It’s my final lecture for the semester.  The pleasure of completing that final lecture is going to be wonderful!

*   *   *
The photograph above was taken on campus several weeks ago--it looks far different from the snow-covered, all-white version of campus today.

Where the Moonworts Lie

Ferns are foreign.  I feel always at some distance from them.  To help prepare my lectures on ferns this week, I went to the library for F. O. Bower’s multivolume monograph The Ferns, which dates from the 1920s.  While some of the ideas in The Ferns may be dated, Bower wrote well, and he was sharply insightful.  I like also the simple line drawings that illustrate the volumes, and I scanned several to use in my lectures. The tone of the fern story is improved, I think, by discussing the most recent phylogenetic trees, which use DNA sequence data to reconstruct relationships among ferns, in the context of slightly yellowed, but simple and clear drawings from Bower’s books.

Since Bower’s time, the idea of a fern has decayed.  The old assemblage of ferns consisted of those plants that had fronds—mostly leaves that were lobed or divided like a feather, a form described as pinnate—and had sporangia on the lower surface of the leaves, although the moonwort ferns were always an oddity when it came to their sporangia.  In the old assemblage of ferns, there were those recognized to have delicate sporangia, which were poised on thin stalks and had a thin wall to surround the spores, and others characterized by relatively massive sporangia.  Those with delicate sporangia were sometimes called the ‘true ferns’ in contrast to those that had ‘indelicate’ sporangia, the moonworts and marattiid ferns

Over the past decade, a group of fern biologists, led by Kathleen Pryer, has produced a series of fascinating phylogenetic studies of ferns.  Their results have shown that the ‘true ferns’ are not the closest relatives of either the moonworts or the marattiid ferns.  The moonworts and marattiid ferns have fallen away from the ‘true ferns’ to lie among the plants once called fern allies.  Pryer and her co-workers have found that the closest living relatives of the marattiid ferns may be horsetails, and the moonworts find their closest relatives to be the oddities sometime known as whisk ferns, the genera Psilotum and Tmesipteris.

Fossil relicts tied to the true ferns, horsetails and marattiid ferns suggest that these were already independent evolutionary lineages over 340 million years ago in the time we call now the Upper Devonian.  Missing from the assemblage of fossils that reach deep into the history of land plants are the whisk ferns and moonworts.  The extant whisk fern Psilotum has a form marvelously similar to those found generally among the earliest vascular plants of the Devonian, but Psilotum has no known fossil record of its own.  The moonworts, the sister lineage of the whisk ferns, have only a relatively shallow fossil record—one composed largely of forms present still today.  Where are those fossils of moonworts and whisk ferns?

Pryer and her colleagues have used DNA sequence differences to estimate that moonworts and whisk ferns shared a common ancestor as recently as 310 million years ago, a date somewhat later than the evolutionary divergences that have given us ferns, horsetails, and marattiid ferns.  Did that common ancestral lineage of the moonworts and whisk ferns have such a generalized form, so lacking in distinctive attributes, that we can’t see its links to those relatives that are alive today?

*  *  *
Among the publications by Kathleen Pryer and her colleagues, I’ve used especially the following two recent papers for background:

Pryer, K.M., A.R. Smith and J.E. Skog. 1995. Phylogenetic relationships of extant ferns based on evidence from morphology and rbcL sequences. American Fern Journal 85 (Special Issue): 205-282.

Pryer, K.M., E. Schuettpelz, P.G. Wolf, H. Schneider, A.R. Smith, R. Cranfill. 2004. Phylogeny and evolution of ferns (monilophytes) with a focus on the early leptosporangiate divergences. American Journal of Botany 91: 1582-1598.

The guttating horsetail

This was a lecture writing day.  At 9.00 this morning, I put a fresh cup of tea on my desk, pulled out relevant papers, Stewart and Rothwell’s paleobotany text, and Gifford and Foster’s morphology text, as well as my old notes to begin constructing tomorrow’s lecture on horsetails.  I looked first at the old notes, and, tentatively, made a couple of Powerpoint slides, which was followed by indecision.  I don’t like indecision when I start writing a lecture so I sat back and drank some tea.  I began again.  Horsetails—the genus Equisetum—fascinate me mostly because they were much more diverse in terms of numbers of species, varieties of forms, and importance in communities a couple of hundred million years ago than they are today.  Horsetails have diminished from trees to spindly stalks.  Something more than a dozen species remain, and they are common in moist environments—creek margins and roadside ditches—in much of the world.  They just aren’t the trees they were 250 million years ago. 

I began the lecture by placing Equisetum in the evolutionary tree of plant diversity, which is the way I set-up our exploration of each plant group discussed in the course.   I wrote about the ecology, form, and reproduction of our extant horsetails.  Then I looked back to ask about the earliest ancestors of this lineage that had horsetail-like traits.  Those earliest relatives of the horsetail lineage are fossils known as Ibyka that date from the Devonian. Ibyka stood at a time when land plants consisted of little more than bifurcating stems, a time before leaves, when there was an evolutionary radiation of the simplest forms.

The fortunate early horsetails were well adapted for so-called coal swamps, the tropical wetland environment that may have been the most productive of its day.  The coal swamp communities appear to have been relatively diverse, and, fortunately, it was an environment that fostered fossilization.  From the coal swamps we have not only compression fossils that show shapes and surface details but also permineralized fossils in which three-dimensional forms and the internal structures have been retained, allowing intricate details of development and anatomy to be examined.  Those coal swamps had tree-like relatives of Equisetum.  I’ve seen some of the largest horsetails that are alive today—they are the species Equisetum giganteum.  You can find them in northern Chile where the plain of the Atacama desert is broken by steep river valleys.  The giant horsetails grow in the tangle of vegetation that holds tight to the riparian margin.  Those giant horsetails are hardly thicker than a finger but are 12 to 15 feet tall.  They seem slightly absurd—wobbly and too tall—and compared to the thick stumps of Carboniferous Calamites, the fossil tree-like horsetail of coal swamps, they seem to have taken a wrong turn.

Perhaps not, however.  The huge arborescent Calamites are gone, now extinct for millions of years, but the thin, teetering contemporary horsetail remains.  Indeed, while not rich in numbers of species, the extant horsetail seems to do well and can spread itself so well that it presents problems for farmers who work moist lowland fields where horsetails can be weedy.

I made Powerpoint slides over the course of the day.  Typing text on slides and then scavenging the Internet and my slide collection for images that would help to demonstrate the ideas more fully.  I took a break at lunch for salad and soup and read the food section of today’s New York Times, then returned to work on the lecture.  The lecture, except for text on the last couple of slides, was finished by 5.00, when I wanted to walk home in the warm light and make a trip to the grocery store before dinner.

There was one image that I couldn’t fit into the lecture.  I posted it above. In the photograph, there are tiny ball-like drops of water at the tips of the horsetail’s branches.  The horsetail is guttating. Guttation is a water transport phenomenon in plants that happens usually on cool, moist days when evaporation from the plant surface is very limited.  On those occasions water diffuses from the soil into the roots, where it enters the water conducting cells. Water pressure, on those cool, moist days, builds-up in the roots, forcing the water upward through the plant body—the effect of which is that water droplets are pushed outward through openings at the surfaces of leaves.  Those emerging droplets are called guttation.  Those moist, creek-side environments where we commonly find horsetails are good places for guttation.

The first exam

It’s only the beginning of the fourth week of classes, but I had scheduled an exam for today.  My advanced undergraduate/graduate plant diversity course consists mostly this year of undergraduates rather than graduate students, and this led me to change the course considerably.  One of those changes was to add an exam near the beginning of the course.  I begin this course with a set of lectures on a few basic concepts (phylogeny reconstruction, homology, novelty, inferences of evolutionary time, and historical biogeography [because I am running behind in my lectures as usual the latter topic will need to wait until the next, post-exam, lecture]) that we will use throughout the semester to comprehend the diversity of plants.  The first exam was scheduled to coincide with the end of the basic concepts lectures and to serve as a punctuation point before we begin to explore various lineages of plants.

I began to write the exam last Friday and finished it yesterday afternoon. There were exams, especially for introductory biology courses that I taught earlier in my career, that I might have spent four days writing—those were the challenging multiple-choice exams in which students would need to work to select among the alternatives.  My first exam for this fall’s plant diversity course took a few hours to write; it’s not too long—only six questions.  I had intended to have only five questions but a couple of them seemed too simple.  And, I suppose, the questions aren’t really questions.  I have been using for this course statements from the botanical literature—snatched from context—and have been asking the students to evaluate them using what they’ve learned in the course.  The quotations I use come sometimes from quirky or esoteric pieces that have been published in recent years but most are from older literature published in the first half of the 20th century, when our knowledge of biological diversity was much skimpier than now.  I enjoy reading through old botanical texts and monographs to find the snippets to use for exams—they are oddly contemporary in the dilemmas the authors present.

As a test I ask the students to evaluate and interpret the quoted statements on the exam in a thoughtful and cogent fashion using the materials from my lectures.  I ask them to compose well-written answers and emphasize that clarity and sense are important aspects of grading. I always look forward to reading the students’ responses on these exams to see how each thought about the issues posed by the snippets I’ve extracted from the literature as well as to see how each has understood the lectures and reconstructed them to respond to the issues of the test.

I distributed the exam in class this morning.  A student suggested that a week would be a reasonable amount of time to complete it, and the other students seemed to agree.  I encouraged them to discuss with each other the quotations on the exam, their meaning and interpretation, and how they related to the content of course; in those discussions, I hope, will be the next phase of learning.  There is learning also, I hope, when the individual students begin to structure and formalize responses for the exam.