UPDATE - October 2013: We no longer have stocks of wild oats. Instead, we recommend using erodium guinum seeds instead, available from Plant World Seeds.
This enjoyable practical encourages students to think about the adaptations that make the Wild Oat such an invasive weed, well adapted to competition in wheat fields. The experiment needs only simple equipment to and demonstrates a variety of physical adaptations to compete in a crowded field. It makes a great activity for a STEM science club or an school open evening.
The Wild Oats awn (hair) is hygroscopic and moves rapidly (within a minute) in response to small changes in humidity. The Student Sheet shows one way of anchoring the seed and exposing it to different conditions so that movements of the awn can be observed and measured.
There are good opportunities here for investigations. Careful control of independent variables such as temperature as well as humidity will be needed, and there is great scope for identifying and measuring the dependent variable e.g. with a protractor and a stop watch.
Once they have carried out steps 1 to 6, students could be encouraged to study the behaviour of the seeds when they are not anchored in blutack and to,try and relate this to the question of why the awn behaves as it does. Careful study of the seeds will reveal that the twisting and untwisting of the awn, combined with the spirally arranged, barb-like hairs at the other end of the seed provide a mechanism which will disperse the seeds and/or bury them in crevices.
Please dispose of the seed used very carefully because wild oat is a virulent weed.