Plants are all around us, but we often take them for granted or pass the mover in favor of life-forms more similar to ourselves. We pay the most attention to them when they flower or provide some specific resource we need (timber, spices, food, etc). The vast majority of plants in the world are unused or infrequently used by us, but that does not lessen their importance and the roles they each play in maintaining a healthy ecosystem.
This page has a slowly growing set of plant-based resources: ID sources, geospatial, and at least one temporal resource.
Please feel free to suggest additional ones.
Adventures in Field Botany/Illustrated Glossary
A nice illustrated collection of field botany terms and plant characteristics.
Huge amount of free agriculturally focused ecology, species, and physical features data in map and GIS form provided by both the USDA and a variety of Russian organizations.
Biota of North America Program
Phytogeographic and Botanical databases for vascular plats all through the US with many incredible maps. Especially the species Density Gradient maps indicating relative plant diversity across the US.
Botanical Society of America Image Collection
Searchable image archive of plants, pollen, fungi, lichens, plant geography, and more.
Flora of Italy
Searchable image archive of plants for Italy, includes scientific name search, region search, botany cards, and a checklist. Site is in Italian.
Forest Service (USDA) Fire Effects Information Home Page
This is an excellent and tremendously underutilized database of detailed plant and animal information provided by the USDA Forest Service. The ostensible purpose is to provide fire ecology information, but the level of detail and information, especially for economically important species, goes far beyond the fire focus. The database is both searchable and browsable.
Internet Directory for Botany
Alphabetical list of online botanical resources. A fantastic resource if you’re looking for country or region specific information. The search function does not seem to work, so it’s slow going searching through for organizations.
Animated maps of species specific vegetation changes over the last 21,000 years in North America, courtesy of NOAA
Tropical Native Species Reforestation Information Clearinghouse (TRIC)
A database of information and resources geared toward reforestation of tropical regions. Searchable by geographic region, resource types, countries, ecosystems, subjects, and more. Great literature list with an easily searchable free literature section as well.