Written and pictorial descriptions of plants are very useful when identifying plants. These can be compared with your unknown specimen to aid in its identification.
Good descriptions direct you to crucial diagnostic features for the relevant taxon, explain the range variability found and point out botanical and ecological characteristics of importance. This website is a good source of information about native plants especially the flora search engine.
Please note—to use an identification guide properly, you need to know enough of the vocabulary to understand the choices presented to you. All good identification guides provide a glossary and a list of abbreviations to help with this.