Organising a herbarium

Today was day one of curation experience. We effectively became volunteers, helping out with tasks to get an idea of what the job is like. I was in the flowering and seed plant division of botany today. After a brief tour, I spent the morning sorting out herbarium sheets a bit like these:

Source: https://commons.wikimedia.org/wiki/File:Joseph_Banks%E2%80%99_herbarium_sheet,_Treasures_Exhibition,_Natural_History_Museum_08.jpg

Each specimen should be representative of the plant. Very small plants can be pressed whole, but for anything bigger than a miniature daffodil it's usual practice to just sample a twig or branch, incorporating a leaf, stem section and reproductive parts. Often, any flowers are pressed on the sheet and fruits and seeds are stored loose, either in a little envelope stuck to the sheet or in a separate box for the big ones. One of the biggest seeds in their collection is the scandalous Lodoicea maldivica (worthy of an image search); that clearly wouldn't dry flat. The NHM has certainly hundreds of thousands of the sheets, probably more, with some dating back to about 1700. But these aren't the oldest: those sheets are stored in another part of the building, in the historical collection, and they date from more like 1550. Fortunately, the sheets I was manhandling were only on the order of decades old(!).

The herbarium had been housed in the Waterhouse building until 2008, the building you probably think of when you imagine the NHM, then moved to the Darwin Centre. Rather than just move the collection across, the curators decided it would be a good opportunity to update their classification system. It's primarily based on taxonomy, which for many organisms underwent massive changes when molecular phylogenetics came on the scene. Flowering plants were no exception. There are still specimens that have yet to be put away in the correct cupboards, though whether most of them are left over from the move or just new specimens coming in I'm not sure. So, our job was to look up the family and genus of these lost souls in the museum's shiny mostly-taxonomically-correct-for-the-time-being index and write, in very careful handwriting, an index number on each that designated which cupboard it belonged in. Handwriting really was crucial: just reading the information labels is a skill in itself, especially with elaborate old-timey cursive.

After lunch, we did another curator a big favour by sticking hand-sized blocks of foam in the backs of cupboards. Unfortunately, these (many many many) cupboards were the wrong size. As you removed stacks of herbarium sheets in their paper folders from the cupboard shelves, the corners could very easily catch on the metal rim of the door, causing a surprising amount of damage. After much deliberation, they decided that the most reasonable solution was to stick these foam blocks behind where the folders sit, shoving them forwards by a centimetre or so, so they don't slip behind the metal rim. But this wouldn't work for the top, bottom or very middle shelves because the sticking-out folders would then stop the door from closing. To make matters worse, the cupboards are stacked, so each line contains two rows. The top row needs a stepladder to get to. Because the folders require very careful handling, a lone curator would need to climb the ladder, take out one shelf's worth of folders (with ten shelves per cupboard), climb down the ladder, put down the folders, climb back up the ladder with the foam, stick the foam in the back, climb back down the ladder, pick up the folders, then climb back up, put the folders away and start again. Because there were six of us we could do this in pairs, the extra hands making a real difference. It was actually great fun.

Finally, we watched a demonstration of the exciting upside-down herbarium scanner, used in their massive digitising project. The NHM is home to a huge number of type specimens, the individual organisms that represent their species. Researchers from all over the world can ask to see the type specimens, usually to help with identifying their own specimens and seeing whether things might be new species. Digitising makes high-quality images of specimens available over the Internet, so researchers don't need to fly across the world to see them. There's been an ongoing project to digitise all of the botanical type specimens for several years.

You can get high-quality scanners easily. The problem with herbarium sheets is that the plants often aren't attached to the paper very well, so turning them upside down is the stuff of botanical nightmares. Someone at Kew solved this problem by building a rig where the sheet sits on a foam platform that can be raised up towards an inverted scanner. They patented it, sold it at very high prices and are apparently now very rich indeed. Unfortunately, to be contrary, the NHM uses a slightly bigger sized herbarium sheet than Kew (and indeed, the rest of the world), so sometimes you need to scan the same specimen twice to get both the top and bottom. At the time of writing, 136,775 NHM specimens have been digitised and uploaded to the JSTOR library (http://plants.jstor.org).

Tomorrow I'll be in palaeontology. They have recommended we wear clothes that can get dirty. Should be fun!