Many Eyes Make Light Work: ROM Field Botany

Posted: August 22, 2012 - 16:35 , by Tim Dickinson

Submitted by David Baxter

As student staff in the ROM Botany Section, my summer work has mostly involved sitting in a basement office updating the plant specimen database, and occasionally working with the herbarium specimens themselves. This last week, however, I’ve been in Montana and Washington searching for Crataegus (hawthorn) trees. Quite a change of pace!

I’m traveling with Tim Dickinson, Senior Curator of the ROM’s Green Plant Herbarium, and we are searching for the very same trees from which people from Tim’s lab (Jen Coughlan, M.Sc. student; Mehdi Zarrei, post-doc; and Cass Shaw, field assistant) collected samples from last spring. Why do we need more samples from the same trees? Did last year’s field crew not collect enough material? Not the case at all! Tim’s lab studies the breeding systems and phylogenetic relationships of the plant genus Crataegus, which has a complicated family history. These trees are able to self-pollinate, hybridize between species, and even produce viable offspring that have a different number of chromosomes from their parents. In order to help sort out these relationships in this genus (and to identify at least the parental species), it is helpful to examine both the flowers and fruits from the same individual. Tim’s students collected the flowering material from these trees last spring, and we’re back here now to collect herbarium specimens with fruit.

A field technician walking along a road to a parked car, with leafy twigs in both hands

The old adage is “Many hands make light work”, but in this case, the hardest work is done with your eyes. We have road atlases and digital maps, a GPS unit and GPS coordinates for each tree we want to sample. This gets us to the site no problem, but once we get there, there’s often several hawthorns, or one big hawthorn thicket, and the only way to know for certain that you’re sampling the same tree is to find the little aluminum tag that the field crew tied to the branch when they sampled the tree last year.

A thick tangle of leaves, branches and small red fruit.

Can you see a little aluminum tag? The prince in "Sleeping Beauty" had it easy.

Finding the little tag is the trickiest part of the job. It is often wrapped around a little branch near the main trunk, so it won’t be noticed by curious onlookers. Sometimes I would be searching a tree for quite some time and Tim would stroll by and see the tag right away, and sometimes it would be the other way around. Once that’s done, we snip off a couple small branches which have leaves, fruit, and thorns (all which are important for identifying the species of a Crataegus), and squish it in our handy herbarium press.

A man tightenings the straps on a bundle of foam sheets and corrugated cardboard with slatted wood on either side

The plant specimens are pressed between blotting paper and cardboard to dry. This 300 year old technology is still the botanical standard today.

The trip hasn’t been without its snags, the most exciting one being when we were driving down the highway along the shore of Flathead Lake and BANG! my passenger-side window is smashed into a thousand pieces. It turns out we were driving past a guy doing some landscaping work and his weedwhacker launched a rock at our car. Luckily, no one was hurt, but we did lose at least a full day out of our seven field days waiting for the window to get fixed in Polson, Montana. In the end, we weren’t able to get to all the field sites we wanted to, but the folks at the cherry orchard where our window broke, the guy at the auto glass place where we got the window fixed, and in fact, everyone we encountered in Montana, were all helpful and friendly.

Now we are nearing the end of our trip, in a motel in Polson finishing processing our specimens in preparation for customs. Although the fieldwork mostly consisted of driving between field sites and looking for little hidden tags, the landscapes of Montana, Idaho, and Washington are breathtaking, and besides, it’s good to get out of the basement once in a while.

A forested mountain range in the background, which a roadside and thicket in the foreground.

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