The UW Libraries catalog points to numerous books, government documents, media (mostly DVD's) etc. relevant to Plant Sciences. These can provide extensive background information on subjects of interest. You can enter a search using the QuickSearch box. Starting with a keyword search often works best. If you find something that's exactly what you want, look at the Subject(s) shown on the detailed display. You can click on any of those that look helpful, and often this will turn up additional relevant sources.
The buttons on the left show available access options. If an item is not at UW you can often get it via Prospector (except articles--see Getting Full Text on the Articles tab); if not in Prospector, use Request It.