About.com: Poisonous Plants for Cats, Dogs, Humans
Article listing a number of poisonous plants, with links to further information about those plants.
http://landscaping.about.com/od/poisonouslandscapeplants/
All Things Plants
Gardening community centered around a jointly edited database of plant species and varieties, with forums and blogs.
http://allthingsplants.com/
BBC: Plant Finder
Plant database with a photo and horticultural description for each entry. Searchable by botanical and common names, as well as other characteristics
http://www.bbc.co.uk/gardening/plants/plant_finder/
BackyardGardener.com: Garden Guides on Plants
Starting point for information on (types of) plants, with summary information for many species and varieties.
http://www.backyardgardener.com/plants/
Cal's Plant of the Week
Features a new plant every week, with photo, description, and cultural information. Previously featured plants can be selected by botanical or common name. Focus is on plants for greenhouse culture.
http://www.plantoftheweek.org/
Chicago Botanic Garden: Ornamental Plant Development
Provides access to plant evaluation reports from the Botanic Garden's plant trials. Each report, in PDF format, provides several pages of description and photos.
http://www.chicagobotanic.org/research/plant_evaluation/
Dave's Garden: PlantFiles
Database with over 80,000 plants with cultivation information and pictures supplied by member gardeners.
http://davesgarden.com/guides/pf/
Desert-Tropicals.com
Features searchable database of thousands of plants, with basic information and often photos. Includes many succulents, herbs, and tropical fruit trees.
http://www.desert-tropicals.com/
Dinosaur Garden Plants
Describes plants that lived during the age of the dinosaurs, with brief information, lists, and links to other resources for plants of the mesozoic era.
http://www.dinosaurgardenplants.com/
Findmeplants.co.uk
Garden plant finder. Searchable by garden conditions and design requirements such as flower color, size and growth habit. Search results include plant photo and summary information.
http://www.findmeplants.co.uk/
Floridata
Features hundreds of plant portraits, each illustrated with several photos, documenting the garden uses and cultural requirements of each species or cultivar.
http://www.floridata.com/
Flower Finder
Search a database of live and cut flowers according to color, usage, and other criteria. Includes photo and summary information for each plant.
http://www.myflowerfinder.com/
Flowers of India
Collection of hundreds of plant photos with brief descriptions. Each of the plants grows in India, but both natives and non-natives are featured.
http://www.flowersofindia.net/
Fruits and Vegetables
Includes set of fact sheets and links from the University of Florida.
http://edis.ifas.ufl.edu/TOPIC_Fruits_and_Vegetables
GardenAway
Plant database with search engine to find plant ideas according to location, design and lifestyle. Free membership gives access to online journal with folders, to-do's and notes.
http://gardenaway.com/
Gardenweb: Name That Plant
Forum that allows users to upload images of plants that they are trying to identify.
http://forums2.gardenweb.com/forums/namegal/
Garten.cz
Features a searchable, multilingual garden plant encyclopedia, with a summary of cultural and botanical information and in many cases photos.
http://www.garten.cz/
GreenerThumb.com
Provides articles on selection, culture, and propagation of several popularly grown perennials and bulbs.
http://www.greenerthumb.com/
Illinois' Best Plants
Chicago Botanic Garden provides a database of recommended plants for Illinois gardens, from perennials to trees, with photos and information on their culture and use.
http://www.bestplants.org/
Jesse Saylor's Plants
Plant information database, including photographs, Latin name pronunciations. Searchable by botanical and common names, and plant characteristics.
http://saylorplants.com/
Mister Smarty Plants
Plant and flower identification: users upload pictures of unknown plants. Site members identify them and score points for correct answers.
http://www.mistersmartyplants.com/
New Jersey Weed Gallery
Database of weeds, accessible by common and botanical names and by a thumbnail gallery. Summary information and photos are provided for each weed.
http://njaes.rutgers.edu/weeds/
Pacific Northwest Plants
Database on plant identification, culture and usage for the U.S. Northwest, including native and introduced species and their major varieties and cultivars.
http://pnwplants.wsu.edu/
PlantBuzz
Gardener Mark McDonough presents horticultural musings and illustrated plant studies, with particular emphasis on alliums and other bulbs for rock gardens.
http://www.plantbuzz.com/
PlantZAfrica
Includes information about plants native to southern Africa, including hundreds of alphabetically arranged plant portraits, by the National Botanical Institute of South Africa.
http://www.plantzafrica.com/
Plants For A Future
Resource centre for rare and unusual plants, particularly those which have edible, medicinal or other uses. Offers a plant database, and various articles on gardening, perennials, and habitats.
http://www.pfaf.org/
Plants National Database
Online USDA database of botanical information, images, and links on plants in the USA, including crops and invasives. Search by name, geographic distribution, or other characteristics.
http://www.plants.usda.gov/
Rob's Plants: PlantLinks
Directory of web pages about plants, selected for their interest to gardeners. Primarily organized by botanical classification.
http://www.robsplants.com/plantlinks/
SunnyGardens.com
Plant encyclopedia featuring photos and short descriptions of annuals, perennials, shrubs, and trees.
http://www.sunnygardens.com/
The Families of Flowering Plants
Offers descriptions, illustrations, and identification retrieval.
http://delta-intkey.com/angio/
The Garden of Paghat the Ratgirl
Pacific Northwest gardener presents essays for hundreds of species growing in her garden, with personal notes, history, cultural information, and photos for each.
http://www.paghat.com/
Translat
Translation program for botanical Latin.
http://members.ozemail.com.au/~pbostock/
WeedAlert.com
Offers a weed listing for the United States regions, primarily weeds occurring in lawns.
http://www.weedalert.com/
