The 'Christmassy' killer raspberry
Since this will be my last blog for 2012, here comes a heartfelt ‘Merry Christmas’ to everyone, with a festive photograph of a fruit that looks like a raspberry. It actually shows a close relative of the raspberry (Rubus idaeus and hybrids thereof) called Japanese wineberry (Rubus phoenicolasius).
Japanese wineberry (Rubus phoenicolasius). [Image from ‘FRUIT – Edible, Inedible, Incredible’ by Wolfgang Stuppy & Rob Kesseler; Copyright Papadakis Publisher, Newbury, UK]
A flesh-eating killer raspberry
Edible and tasty, although not as delicious as a real raspberry, this native of northern China, Korea and Japan is sold by nurseries in the UK and grown by some people in their gardens. Unlike a regular raspberry, the calyx surrounding the fruit of a Japanese wineberry, is covered in sticky glandular hairs, similar to those found in carnivorous plants such as sundews (Drosera spp.). This has led some people to assume that Rubus phoenicolasius might actually be a carnivorous raspberry. A flesh-eating killer-raspberry? Sensational!
The calyx that surrounds a Japanese wineberry (left) is covered in glandular hairs which are very similar to those of carnivorous sundews, Drosera capensis (right). (Photos: Wolfgang Stuppy)
Well, not quite. A thorough scientific investigation in 2009 (pdf) has busted this myth. Although the glandular hairs of a Japanese wineberry contain tannins that help ward off herbivores, the mucilage they secrete does not contain any digestive enzymes and neither are the hairs capable of taking up any potential solutes. The sticky hairs on the calyx are mainly there to protect the bud from insect predation but not to kill and devour any creatures - although very small insects may become trapped and die.
The making of ...
Returning to the actual picture of the fruit shown at the beginning, you will have noticed that this is not a straight ‘shot’ with a regular camera. In fact, the image is taken with a Scanning Electron Microscope (SEM), a very expensive device that uses an electron beam instead of light to scan and visualise objects.
One of Kew’s Scanning Electron Microscopes at the Jodrell Laboratory (photo: Wolfgang Stuppy)
The advantage of an electron beam is that it has a much shorter wavelength than light. As a consequence, the resulting image has much greater depth of field and resolution, giving it a hyper-realistic look. The only disadvantage is that an electron beam has no ‘colour’ and so the resulting image comes in black-and-white only. To ‘spice-up’ the very ‘sciency’ monochromatic appearance of SEM pictures, I have teamed up with artist Rob Kesseler. Our fruitful (excuse the pun) collaboration started in 2005 and since then we’ve done quite a few crazy things in the lab which no respectable scientist would ever do. One was shuffling a whole Japanese wineberry into the vacuum chamber of a Scanning Electron Microscope.
Our specimen of a Japanese wineberry covered in a fine layer of platinum as a preparation for observation in the Scanning Electron Microscope (photo: Wolfgang Stuppy)
A microscope, not a macroscope!
As its name implies, a Scanning Electron Microscope is an instrument with which to magnify very small things to make them visible. At a diameter of about 2 cm, a Japanese wineberry isn’t exactly something you need a microscope to look at. So when we decided that an SEM ‘photograph’ of this fruit would look very ‘cool’, it was no surprise to discover that it was far too big to fit into the SEM’s field of view. Determined to succeed, we were forced to take 56 individual images which Rob then had to painstakingly stitch together into one. The rest is history.
The beginning of the jigsaw-reconstruction of the Japanese wineberry from 56 individual SEM photographs (image: Wolfgang Stuppy & Rob Kesseler)
Many thanks to everyone who has followed my blog so far and for the encouraging feedback. I know now that although I am probably the only Seed Morphologist in the village, I am surely not the only person who believes that seeds are amazing!
The seed of Floscopa glomerata, a member of the spiderwort family (Commelinaceae) from Mali, dressed up as Santa Claus. [Seed image from ‘SEEDS – Time Capsules of Life’ by Rob Kesseler & Wolfgang Stuppy; Copyright Papadakis Publisher, Newbury, UK; Santa hat design: Gemma Toothill]
- Wolfgang -