The range or distribution maps on eFieldGuide.com are based on two different sets of data. An example map is shown below. The areas that are light green in color are based on data from the USDA PLANTS Database. Most of this data is from historical sources, like literature references and herbarium specimens. This data is not up-to-date, and may not always represent the current range of the species. The darker green areas are based on data from the eFieldGuide.com Data Group. This data is 100% up-to-date, and is provided by the members of the Data Group. If a species is growing in your area, but you don’t see it highlighted in dark green on the map, that means the Data Group needs your help! You can join the Data Group and submit the data, to help increase our understanding of the current range of each species. The maps are updated regularly as new information is reported from the Data Group. This helps to make the maps on eFieldGuide.com some of the most current found anywhere on the web!