Vehicles have been identified as a mode of seed transportation. As the impact of non-indigenous and noxious plant populations becomes a more pressing issue, it is important to know how and what species of plant seeds are being transported by vehicles. Current methods of determining what kinds of seeds are spread by vehicles involve an aggressive wash of the underside of the vehicle. The washwater is then collected and the seeds are sieved off and inspected. The seeds are then sprouted in order to more precisely identify the species of plant. This process, however, damages fragile seeds, limiting the ability to identify what was transported by the vehicle. Fixtures designed to replicate the shape and size of nooks and niches on the underside of a vehicle to catch soil and seeds, and engineered to attach and detach from the vehicle with simple hand tools or quick release mechanism hardware, can then be subjected to a gentler wash and rinse so that damage to seeds is minimized.