botanizing

Collecting the new Mentzelia

I stay close behind Melissa.  She walks up the desert wash in Chaco sandals and a skirt.  Her steps are swift and balanced.  It is difficult for me to match her pace. She walks through the creek.  I plant one huge hiking boot at the creek’s edge and look for a stepping stone at midstream—which I don’t see—then stretch my stride to reach as far across the creek as possible.  Melissa, who works for the National Park Service on vegetation management, found last fall a new population of our likely new species of Mentzelia.  Today, she’s taking us to the population.  Melissa had been working with her vegetation survey crew to gather data on the effects of tamarisk removal.  We arrived as she and her crew were finishing lunch.  Melissa put down her lunch box to lead Wendy, Max, Heidi, and I the half mile or so up the side canyon to the location where she found the new population of the new Mentzelia. 

Seeing the population will provide me with important details about the kinds of environments used by this unusual subshrubby lineage of mentzelias.  I want also to collect some additional individuals so that we can understand better the variation characteristic of this new species.

“It’s along here,” Melissa says and slows to look at the gravelly hump along the spine of the creek’s channel  “There it is,” she says a moment later and points to the plant.  The Mentzelia is growing in compacted gravel and sand in a shallow bank along the creek.  It’s an odd place for a Mentzelia of this sort—we usually find relatives of this species growing on steep slopes of loose rocks or on knolls that have gypsum crusts.  “There’s another one along here,” Melissa says.  I look up the creek and then see the other, smaller plant a few feet from the first one.  

Wendy, Max, and Heidi arrive, and we all admire the new mentzelias.  “We should expect them on these slopes,” I say, and we disperse to climb the loose, mud-colored stone of Muav limestone.  Wendy is above me on a steep slope when I begin to find additional plants.  She climbs to one of the plants that is growing on a stack-like outcrop of stone, and here she finds a single open flower.  We had not expected open flowers in this population, which we expect to flower later in the summer like other closely related subshrubby mentzelias.

As I walk along the slope above the creek, I find more individuals of the Mentzelia.  They appear to be most frequent in the angles where stone outcrops meet the talus slope, which probably offers some advantage in increasing the amount of water available.

Wendy sits in the wash to press our collections of the Mentzelia.  We talk about the oddness of finding the plants growing in the unstable wash, which has the advantage of offering more water than the steep, talus slopes but would be prone to scouring floods that could wash the plants away.  As we talk about the possibilities of the plant’s seeds to germinate and establish themselves in the wash, I look down and see five young seedlings of the Mentzelia.  These are young plants that probably germinated earlier in the spring.

Finding the Mentzelia population has given me a huge energy boost—which I need because we are soon expected at the rafts to continue our trip downriver this afternoon.  I fill my hat with water and put it on my head.  We begin swiftly to walk down the wash.

[this essay dates to 4 May]

The mow of flowers

We occupy a mow, once part of a cotton mill, in Durham, North Carolina, and the back wall, beside a tall window, consists mostly of a large door, sealed now by fresh, white paint, where cotton bales may have passed.   The mow is now a conference room, and we fill the space of a long table.  I sit for the week near the back, by the tall window of 24 panes, and I turn periodically to watch the light change, the rain fall, and the branches of a tree, sometimes steady and sometimes wavering in the wind.  The mow, table, window, and the ideas we discuss are part of the National Evolutionary Synthesis Center (NESCent).

NESCent is funded by the National Science Foundation to advance synthetic research on basic questions in evolutionary biology.  I am part of a working group that is funded by the center to explore the evolution of flowers.  Our working group, which consists of plant biologists from various universities and botanical gardens in North America, Mexico, and Europe, including well established scientists as well as some who are early in their careers, begins with a morning and more in which each of us gives a brief talk about the issues and questions that drive our research.  Show no more than five slides and talk for no more than ten minutes, we have been told, and we each condense our work, sometimes from decades, into haiku, a few bright lines that evoke the scene of our ideas and the seasons of our outlooks on the evolutionary landscape.

Here is what I say:   Patterns of plant diversity in nature drive my curiosity and research questions.  I try to understand diversity by first building evolutionary trees, so-called phylogenies, that show relationships among lineages of plants.  Using phylogenies, I characterize diversity patterns we see among the forms of plants, and I ask about evolutionary processes that may have created those patterns.  My research also uses phylogenies to revise classifications of plants.  For example, I like to model existing or previous classifications as phylogenies to test whether they are robust to the evolutionary signals we find DNA sequence data.  For the past few years in my lab, we have also been asking questions about geographical patterns of diversity.  This research uses the distribution of genetic diversity in populations and species of plants to reconstruct migration patterns and evolutionary processes, and I have been especially directed this work toward understanding the history of plants in the American West.

The brief talks serve as introductions, although we are each largely familiar with the interests and publications of the others in the room.  The talks serve also to place perspectives on the table so that we can see the positions and experiences that will come to play over the week.

We finish the first day by discussing what we want to achieve and some preliminary analyses that the organizers have conducted to stimulate conversation.  One of the issues that we wish to explore is whether certain sets of floral attributes have evolved to co-occur independently many times in different groups of plants.  Such independent origins of co-occurring traits are often seen as a signature of evolutionary adaptation but one in which diversity, shaped by natural selection in similar environments, converges on a few handfuls of common forms.  In flowers, these are forms like petal tubes that have few stamens, which have been repeatedly selected by pollinators such as moths and butterflies that have long mouth parts and hummingbirds that have long, narrow beaks.  A second issue that we wish to address is more general, and that is how the grand diversity of flowers has been assembled through evolutionary time.  This question is one that many of us have investigated and written about repeatedly for many decades; it is a question that concerned biologists and natural historians well before any of us in the NESCent mow began our work on flowers.

The synthesis we wish to achieve will need to come from fresh analyses but not from fresh data.  We will borrow data from the scientific literature, but we will build a new framework to analyze those data.  The discussions of our working group target that framework.  Where will we get the phylogeny that will serve as the basis for our analysis?  How many plant groups must we sample and how will we sample those groups?  What attributes of flowers do we wish to include in the study and how do we characterize those attributes?  Once we have the selected the plant groups, reconstructed the phylogeny, and have our data on the characters of flowers, how will we conduct the analyses?  These are the questions we discuss on Wednesday, Thursday, and Friday.

We meet each morning at 8.00 to take a van to the old mill, where we grind ideas in the mow until 7.00 p.m., when we break to have dinner together.  The days are mentally exhausting, but I am also physically tired each evening.  Synthesis is hard work, and I fall asleep early and quickly each night.

Friday work

I pushed the power button on my laptop at 9.00 this morning and walked out to fill the tea kettle with water.  I swished a bit of water around my deeply stained teacup and rubbed my thumb about its rim.  From there, I headed across the street for a muffin and a copy of The New York Times.  Back at my desk, my e-mail had a second request from a professional journal for a manuscript review (I like to let these requests age a little before I respond).  I sent a reply, agreeing to write the review but noted that it would take a few weeks because already two grant proposals and a manuscript from another journal make a small pile on my desk.  After scanning the rest of my e-mail, I deleted most it.

On Fridays, I meet individually with each of my graduate students.  This is a routine that I very much like.  No matter how many times I may chat with my students during the week or look at their data or answer questions, I like the ritual of a regular Friday meeting devoted to each student.  We review results and problems and plan for the next steps of research.  There are times when students will come in with a plan to distract me from the needs at hand and at other times one will dash in to say he/she is at work in the lab and has nothing other to say than he/she is returning that moment to the lab.  A meeting need not last long to have value.

I still hadn’t poured my tea water when B arrived for his meeting at 9.30.  I ran out to pour tea and let it steep while B explained results of his phylogenetic studies after adding new data.  His study of hybridization and polyploidy in phylogenetic diversification involves unruly data that he works hard to understand.  As we talked, he held a sheet of paper, on which was printed a preliminary phylogenetic tree.  Like a real tree, this phylogenetic tree had many branches and crowded at their tips like leaves were the tiny names of the many plants B had sampled.  I put on my glasses and squinted over my teacup to see the evolutionary relationships as he talked.

After that first meeting, I went in search of my student J.  She and I had worked this week to prepare a prospectus of her MS research to give to her thesis committee at a meeting scheduled for this afternoon.  We reviewed my few final suggestions for the document and talked more about work that she might do for her thesis.  J and I had talked in the prep room of the herbarium, where we sat at a large work table.  When we finished I went back to my office, which is in the herbarium’s complex of rooms on the ground floor of our building.

My next meeting was with S, who is gathering the last data for his dissertation and writing papers based on data collected earlier.  He has also just submitted his first job application.  We talked about job applications and letters of recommendation as well as about data and the papers we are writing.  When J left, I heard him call to my other graduate student, N.

N came in with a stack of papers and her laptop.  N started PhD studies this semester, and we are designing her dissertation project.  This is one of my favorite parts of training graduate students.  She told me about the articles she had read during the past week and handed me copies of those that were especially relevant to her research.  On a high pile of papers that persists on my desk, N set-up her laptop to show me data that she had amassed from the literature.  There were patterns and questions in those data that may be the beginnings of new research.

It was nearly noon when the meetings with my graduate students were finished.  I checked my e-mail, where there was a request for my signature.  I went up to the departmental office, where I signed a form to pay for recent research charges in my lab.

There was a time when I would dash up to the student union for a freshly made stir-fry or a salad for lunch while having a quick look at the Times.  Those good lunches took about 30 minutes.  A couple of years ago the student union was closed for remodelling and when it re-opened this fall the only food available was fast food.  Now the student union has a lovely interior with plenty of computer games and video screens, but there is no fresh food and little that is green and vegetable.  I’ve been walking home for lunch when possible over the past couple of years.  It’s a 12 minute walk and delightful in this season, although not always so pleasant in the winter snow or spring rain.  Today I nudged a few fallen leaves as I walked.  I had a small turkey sandwich, two slices of melon, radishes, grapes, a pickle and was back in my office about 1.00.

For an hour, I worked on a letter of recommendation and then went to J’s committee meeting.  She did a great job of telling us about her plans, and her committee members asked questions.  The discussion helped to refine some of the research plans.  We finished about 3.00, and J and I walked back to the herbarium. 

J mentioned to me that one of my colleagues has lab meeting from 3.00 to 5.30 on Friday afternoons, and I asked her whether we should switch to that format.  (My lab meetings, where we discuss current research literature, are on Tuesdays after lunch)  We talked about lab meeting formats with a couple of my other grad students for a few minutes, and then I headed back to my office.  It was time to return to that letter of recommendation that I had started earlier.  I typed for the rest of the afternoon, then closed-up my laptop and put it in my backpack for weekend work about a quarter until 5.00.

Many Times Repeated

Leaf after leaf.  A series of opportunities.  I have been thinking about evolutionary opportunities.  Charles Darwin saw a source of evolutionary opportunity in bodies in which parts were “many times repeated.”  He wrote in the first edition of Origin of Species that:

“We have formerly seen that parts many times repeated are eminently liable to vary in number and structure; consequently it is quite probable that natural selection, during a long-continued course of modification, should have seized on a certain number of the primordially similar elements, many times repeated, and have adapted them to the most diverse purposes.”  (p. 418)

In the spiral stairs of leaves around the artichoke, we see an example of Darwin’s “parts many times repeated.”   These leaves of the artichoke, however, are all alike—little evolutionary opportunity has been taken on the artichoke’s leafy head.  In contrast, flowers demonstrate well the sense of Darwin’s idea.  Orchid flowers often have one petal, the lip, that is highly modified relative to the other petals.  We might even think about the transition in structure from petals to stamens, as in the photograph below of a nasturtium, as an example of modification among ‘parts many times repeated’ in flowers.

These evolutionary opportunities presented when parts are ‘many times repeated’ in the body of plants interest me.   How does evolution go from simple repetition of parts, as we see among the leaves of an artichoke, to the variation and specialization we find along the short length of a flower?

Hydrangea 2007

Hydrangea 2007, an international conference (http://www.hydrangea2007.be/en.php) devoted to hydrangeas for enthusiasts and gardeners, is approaching, and I’m speaking.   The conference, which will be held at the Ghent University Botanical Garden in Belgium, begins on 16 August.  And on Friday, I began work on my talk.  This involved perhaps an hour of pacing, and then I fixed tea, and then I made a trip to a vending machine for some chips.  With tea and chips, I settled into writing.

I typed my title—‘Becoming Hydrangea’—and went on to the senses that I want the audience to take from it. The first is an evolutionary sense—I want to convey the changes that occurred in Hydrangeaceae, the hydrangea family, to give rise to the plants that we recognize as hydrangeas. The hydrangea family includes several genera in addition to Hydrangea, and many of these would not be popularly recognized as cousins of Hydrangea.  The second sense of ‘becoming Hydrangea’ is taxonomic. Our studies to reconstruct the evolutionary history of the hydrangea family have shown that Hydrangea in an evolutionary sense is broader than what Hydrangea has been in recent taxonomies.  If we are to understand the diversity of hydrangeas, we need to change our taxonomy to reflect better our understanding of evolution in the Hydrangea lineage.

On Friday, I wrote those introductory ideas, explaining our knowledge of the evolutionary history of the family, how it is most closely related to Loasaceae, another family of research emphasis in my lab, and more deeply related to dogwoods, tupelo, and the dovetree.  I sketched notes on the timing of the evolutionary split between Loasaceae and the hydrangea family and described the geographic radiation that occurred within Hydrangeaceae.

After cleaning the bathroom, getting groceries, and starting a load of laundry, I went today to the writing table in the basement as the afternoon heat began to rise in my house.  There I wrote about the ecological and morphological changes that mark the lineage that would become Hydrangea and also began to write about the broadened sense that we need for the genus. 

Finally, the lineages of Hydrangea came up; I began to think about the important points that I would like to make about the diversity we find in Hydrangea.  And I began wonder where I’ve stored all of the images I’ve used over the last decade in talks about the evolution of hydrangeas.  This is a topic I haven’t addressed in detail for a few years, and I hesitate to think about the out-of-date storage devices on which all of my electronic files have been stored. 

Tomorrow morning, first thing, I must look for the cache of electronic images as well as the hoard of negatives and slides that I will need to make new images for the talk.

Composing

For the past several days I’ve been composing a research talk.  I’ll leave this weekend for a trip to Saskatoon for Plant Canada 2007, a meeting of various Canadian plant science organizations at which I’ve been invited to speak. 

On a cool day nearly two weeks ago, I started a fire in my fireplace and sat in my rocking chair with a yellow pad to sketch the arc of my talk.  Earlier in the spring I had submitted a title and abstract, which set the themes to address.  I outlined the set of data, how they would be ordered, and the basic conclusions, but other aspects of the talk’s arc occupied much of the thinking time in front of the fire.  History and ideas add significant depth to talks and can serve as the plot lines to propel the arc of the story.  It’s those elements that take quiet thought in the rocking chair as well as several cups of tea and trips into my library (even trips into my office).

From the sketch, I composed a rough script of the first third of the talk, a point where I was undecided about the best way to proceed.  That catch led me to begin making the visual presentation.  These talks are strongly visual and working on the Powerpoint slides can sometimes offer insights on how best to structure the information.

Another of the critical questions these talks raise is how to convey ideas with pictures. I’ve been asking myself idea by idea, bits of data by bits of data, slide by slide how to compose.  This is the consuming part of the process.  I worked steadily on slides for several days, thinking about their aesthetic appeal and focal points as well as the clarity of the ideas.  The slides need to hold audience attention, convey swiftly the ideas, and also give me a set of clues about what to say (because I won’t be using either script or notes).

I’ve scavenged slides from an old talk, but the ideas of the new talk are sufficiently different that most of the slides will be new for the Saskatoon talk.  Most slides will have one or more photographs; indeed, one slide has 13 photographs and a diagram.  My photographs of research materials have been captured largely on film, requiring me scan Kodachrome slides to acquire digital images to import into Powerpoint.  I’ve been scanning in the late afternoons after spending the day laying-out slides and writing text.  My mornings often have begun by cropping and adjusting the lighting of the digital images.  These images were then imported to fit around text and/or diagrams.  Many of these slides, which may be on the screen for no more than a minute, often take several hours to make.  This week there have been several ‘single slide days.’

I finished the slides of the Powerpoint presentation late on Thursday night and drafted the last few notes this morning.  I’ve printed the notes to use as I practice the talk to check how the information flows, to make sure the descriptions work, and to know precisely what points to make with each slide.  And I need to know that the talk will fit the time that I’ve been allotted. 

This evening I began to pack clothes, apples, oranges, and tea.  I’ve set my thermos on the counter to fill tomorrow morning with hot water.  My binoculars and bird book are with my camera.  First thing tomorrow morning, I’ll start driving north.

*  *  *
The photograph is Mentzelia multiflora and is one of the images I'll use in my talk on evolutionary innovation in flowers.