Some help identifying plants on very useful sites
The countries and/or regions are in alphabetical order by English names.
General
http://www.farmalierganes.com/Flora/Angiospermae/Orobanchaceae/Host_Orobanchaceae_Checklist.htm (English)
Orobanchaceae and their host plants
Distribution/occurrences
https://www.gbif.org/species/search Worldwide
http://ww2.bgbm.org/europlusmed/query.asp Euro-Mediteranean
http://siflore.fcbn.fr/?cd_ref=&r=metro France
http://www.anthos.es/ Spain
http://www.floraweb.de Germany
https://www.brc.ac.uk/plantatlas/ Great Britain and Ireland, BSBI
Names/synonyms/taxonomy
http://www.plantsoftheworldonline.org/ Plants of the World Online (POWO)
www.theplantlist.org/ the Plant List (TPL; not updated anymore)
http://ww2.bgbm.org/EuroPlusMed/query.asp Euro+Med plant database
http://www.tropicos.org/NameSearch.aspx Tropicos (Missouri Botanical Garden database)
http://www.ville-ge.ch/musinfo/bd/cjb/africa/recherche.php African Plant database (Jardin Botanique de Genève)
https://www.nederlandsesoorten.nl/linnaeus_ng/app/views/search/nsr_search_extended.php?group_id=118264&presenceStatusList=&dna-options=&group_id=&sort=name-valid&just_species=0&group=Tracheophyta Nederlands Soortenregister (Naturalis)
EUROPE
General
http://www.guenther-blaich.de/pflla.php?lan=E&wid=1293 Photos of European Plants according to Scientific Names
Austria
http://flora.nhm-wien.ac.at/Seiten-Allgemein/Pflanzengattungen.html (German) Good pictures, but incomplete
http://blumeninschwaben.de/ (German) Good keys, complete, good pictures
Czech republic
https://www.biolib.cz/en/gallery/dir23/http://blumeninschwaben.de/ (German) Good keys, complete, good pictures
Finland
http://www.luontoportti.com/suomi/en/kasvit/ NatureGate (7 languages)
France
http://www.florealpes.com/ (French) photographs of very high quality, with some useful tricks how to distinguish between 2 species ('lancer comparaison')
http://canope.ac-besancon.fr/flore/ (French)good descriptions and differences with similar plants
http://www.tela-botanica.org/ (French) – pictures (not always correct!), areas and descriptions (not complete)
http://www.jeantosti.com/Fleurs.html (French) the Roussillon area (Pyrenées orientales)
https://www.cbn-alpin.fr/Atlas/AtlasFlore/CartesEspeces/MenuAtlas.htm (French) French alps
http://www.fauneflore-massifcentral.fr/botanique/ (French) Central France
Georgia
http://biodiversity-georgia.net/ (English)
http://apa.gov.ge/en/biomravalferovneba/mtiralas-erovnuli-parkis-biomravalferovneba (English)
http://www.unifr.ch/ecology/groupmueller/research/current-projects/invasive-plants-georgia (English)
http://gov.ge/files/50911_50911_140443_413-1.pdf (English)
https://ekonferans.artvin.edu.tr/index.php/ICFS/ICFS/paper/viewFile/200/213 (English)
Germany
http://blumeninschwaben.de/ (German) Good keys, complete, good pictures
http://worldplants.webarchiv.kit.edu/D/index.php Flora von Deutschland - Eine Bilder-Datenbank (German)
http://www.floraweb.de/pflanzenarten/pflanzenarten.html (German)
Great Britain and Ireland (English)
http://bsbi.org/identification PlantCrib, advanced botany for Great Britain/details appear in PDF docs
http://www.botanicalkeys.co.uk/flora/ Identification keys for British and Irish plants
https://www.brc.ac.uk/plantatlas/ Ecology, maps, pictures
http://www.aphotoflora.com/ SW England
http://www.botanicalkeys.co.uk/northumbria/ NW England
Greece (English)
http://portal.cybertaxonomy.org/flora-greece/intro Pictures, distribution
http://www.west-crete.com/flowers-crete.htm Crete and Greece
http://www.cretanflora.com/ Crete
http://www.tilo-botanica.eu/index.html the isle of TILO
http://wildflowersofskopelos.org.uk/Blog.html the isle of Skopelos
http://worldplants.webarchiv.kit.edu/rhodos/index.php
Iceland (English)
http://www.iceland-nh.net/plants/ (Dutch, English)
Ireland (English)
http://www.wildflowersofireland.net/http://www.habitas.org.uk/flora/splist.asp?Sort=latin&Family=&PlantGroup
Italy (Italian)
http://luirig.altervista.org/flora/taxa/floraindice.php per region, good pictures but no identification keys
http://www.actaplantarum.org/ excellent site
Malta (English)
http://www.maltawildplants.com/wildplants_index.php Description and pictures
Club Med (English)
http://www.florasilvestre.es/mediterranea/ (Spanish) Western Mediterranean area
http://www.mittelmeerflora.de/ (German) Identification keys and pictures for Mediterranean Europe
Netherlands/Low countries
http://www.soortenbank.nl/hoofdgroepen.php?groep=Planten&selectie=2&hoofdgroepen_pad=%2C2 (Dutch) Soortenbank, keys. Not updated anymore
https://www.verspreidingsatlas.nl/planten (Dutch) Verspreidingsatlas.nl; Actual distribution, descriptions, some pictures.
https://www.floron.nl/ (Dutch) FLORON, Floristic research
http://alienplantsbelgium.be/ (English) Manual of the Alien Plants of Belgium
http://natuurtijdschriften.nl/search?portal=natuur;smode=simple-modify (Dutch, English) Repository of journal articles
http://natuurtijdschriften.nl/search?sort=releasesort&portal=natuur&browse-journal=yes&f1-journal=Gorteria (Dutch, English) Gorteria-Dutch Botanical Archives
Norway (Norwegian)
https://www.artsdatabanken.no/ where to find species
https://www.artsobservasjoner.no/http://www.naturfakta.no/planter/?navn=etterfarge.htm search by colours
http://www.kristvi.com/testdb/alfabetisk.php?sort1=latin&test=1 good pictures
NW-Europe
http://blumeninschwaben.de/bestimmungsschluessel.htm (German) Identification keys and pictures for North-western Europe
Portugal, Madeira, Azores
http://www.flora-on.pt/ (Portuguese) good pictures, not complete (yet), link to Flora Iberica
http://siaram.azores.gov.pt/flora/flora-vascular/_intro.html (Portuguese)
Pyrenees
http://atlasflorapyrenaea.org/florapyrenaea/index.jsp (Spanish, Portuguese, French) Atlas of flora of the Spanish and French Pyrenees
http://www.lafloredespyrenees.fr/ (French) only pictures
http://azunpeche.free.fr/flore.htm (French) mainly the Val d’Azun
Russia (Russian, Cyrillic)
http://www.plantarium.ru/page/taxonomy/taxon/42054.html (Russian), but using right-clic "translate", you could use it.
http://www.efloras.org/flora_page.aspx?flora_id=2 (English)e-Flora of China. Complete flora of China (including Taiwan) with keys and some good drawings
Scandinavian countries general (Swedish)
http://linnaeus.nrm.se/flora/ good pictures + maps
www.artportalen.se where to find species
Spain (Spanish)
http://www.floraiberica.es/PHP/generos_lista.php Flora Iberica, very good identification keys with drawings; on pdf, but not complete yet
http://www.bioveg.uma.es/varios/florandor/florandor.html downloads for pdf of Flora of Eastern Andalusia (Oriental) and Western Andalusia (Occidental), very good floras but it takes long to download
https://www.floravascular.com/ Western Andalucia
http://www.almerinatura.com/joyas/ around Almeria
http://flora-aragon.blogspot.fr/ Aragon
http://www.florssilvestresdecatalunya.com/indice_latin_flors_silvestres_de_catalunya.php Catalunya
http://www.apatita.com/herbario/indice/ecologia/arenales.html Alicante region
Switzerland
http://www.wsl.ch/land/products/webflora/floramodul1-en.html Distribution maps of Swiss flora; horrible pictures but a good checklist
https://www.infoflora.ch/en/ (English) good descriptions, pictures, no keys; based on the Flora Helvetica
http://blumeninschwaben.de/ (German) Good keys, complete, good pictures. Probably does not cover all swiss endemics?
AFRICA
Botswana
https://www.botswanaflora.com/index.php (English) Flora of Botswana, excellent quality of pictures and descriptions, no keys
Caprivi strip
https://www.capriviflora.com/index.php (English) Flora of the Caprivi Strip (Namibia), excellent quality of pictures and descriptions, no keys
Egypt
http://westerndesertflora.geolab.cz/index.php (English) Common Plants of the Western Desert of Egypt
Gabon
http://portal.cybertaxonomy.org/flore-gabon/cdm_dataportal/taxon/e1a39297-c0e1-40d6-98b8-05ddd9c8a9ea/synonymy (French) Flore du Gabon, excellent flora, but only the old text are included
Malawi
http://www.malawiflora.com/ (English) Flora of Malawi, excellent quality of pictures and descriptions, no keys
Morocco
http://www.floramaroccana.fr/la-flore.html (French)
https://www.teline.fr/en (French and English)
http://www.florasilvestre.es/mediterranea/index_maroc.htm (Spanish)
Mozambique
https://www.mozambiqueflora.com/speciesdata/index.php (English) Flora of Mozambique: excellent quality of pictures and descriptions, no keys.
Zambia
https://www.zambiaflora.com/ (English) Flora of Zambia: excellent quality of pictures and descriptions, no keys
Zimbabwe
https://www.zimbabweflora.co.zw/ (English) Flora of Zimbabwe: excellent quality of pictures and descriptions, no keys.
West Tropical Africa
https://ia802304.us.archive.org/24/items/FloraOfWestTropi00hutc/FloraOfWestTropicalAfrica-JohnHutchinson.pdf (English) download link of Flora West Tropical Africa, an excellent standard work, with annotations
http://www.westafricanplants.senckenberg.de/root/index.php (English) West African Plants-A photo Guide. Incomplete and with some errors still valuable
Central Africa (Congo-Kinshasa, Burundi, Rwanda)
http://www.plantentuinmeise.be/RESEARCH/DATABASES/FOCA/index.php (French) Flore d'Afrique centrale. Excellent quality, but no pictures/photographs
http://www.centralafricanplants.senckenberg.de/root/index.php (English) Central African Plants-A photo Guide. Incomplete and with some errors still valuable
East Africa (Congo-Kinshasa, Burundi, Rwanda)
http://www.eastafricanplants.senckenberg.de/root/index.php (English) East African Plants-A photo Guide. Incomplete and with some errors still valuable
ASIA
General
https://rbg-web2.rbge.org.uk/thaiferns/ (English) Ferns of Thailand, Laos and Cambodja
http://portal.cybertaxonomy.org/flora-malesiana/node/38 (English) Flora Malesiana (Indonesia, Malaysia, Singapore, Brunei Darussalam, the Philippines, and Papua New Guinea)
China
http://www.efloras.org/flora_page.aspx?flora_id=2 (English) e-Flora of China. Complete flora of China (including Taiwan) with keys and some good drawings
India
https://sites.google.com/site/efloraofindia/species (English) efloraofindia
Mongolia
https://floragreif.uni-greifswald.de/ (English) Virtual Guide to the Flora of Mongolia.
Nepal
http://www.efloras.org/flora_page.aspx?flora_id=110 (English) Annotated Checklist of the Flowering Plants of Nepal
Russia (Russian, Cyrillic)
http://www.plantarium.ru/page/taxonomy/taxon/42054.html (Russian), but using right-clic "translate", you could use it.
http://www.efloras.org/flora_page.aspx?flora_id=2 (English)e-Flora of China. Complete flora of China (including Taiwan) with keys and some good drawings
AUSTRALIA AND NEW ZEALAND (English)
http://lepidoptera.butterflyhouse.com.au/plants/index.html Flowering Plant Families in Australia
http://www.nzflora.info/ The definitive reference to New Zealand plants
MIDDLE EAST (English)
Israel
http://www.wildflowers.co.il/english/plantsIndex.asp Flowers of Israel
http://flora.org.il/en/plants/ Flora of Israel Online
Qatar
http://www.unesco.org/new/uploads/media/Plant_Species_Checklist_of_Qatar.pdf An Illustrated Checklist of the Flora of Qatar
Saudi Arabia
http://www.plantdiversityofsaudiarabia.info/Biodiversity-Saudi-Arabia/Flora/Flora.htm Flora of Saudi Arabia
SOUTH AMERICA
Argentina
http://www.floraargentina.edu.ar/ (Spanish) Flora Argentina
Brazil
http://floradobrasil.jbrj.gov.br/reflora/PrincipalUC/PrincipalUC.do;jsessionid=F6710320FE44F0CD50C3E662C25B6E30 (Portuguese)
http://floradobrasil.jbrj.gov.br/reflora/listaBrasil/PrincipalUC/PrincipalUC.do?lingua=en#CondicaoTaxonCP (English)
Chile
http://www.efloras.org/flora_page.aspx?flora_id=60 (English) e-flora Flora of Chile
Ecuador
http://www.efloras.org/flora_page.aspx?flora_id=201 (English) e-flora Trees and shrubs of the Andes of Ecuador
Guianas (French Guiana, Suriname and Guyana) (English)
http://portal.cybertaxonomy.org/flora-guianas/
Caribbean)
Plants of the Eastern Caribbean (English) Plants of the Eastern Caribbean
NORTH AMERICA (English)
http://www.efloras.org/flora_page.aspx?flora_id=1 e-Flora of North America. Complete flora of North America with keys and some good drawings
http://www.calflora.org/ Very reliable photo database of California
http://www.americansouthwest.net/plants/wildflowers/arizona.shtml Arizona
http://worldplants.webarchiv.kit.edu/PA/index.php Pennsylvania and New Jersey
Last modified 19-03-2019. Updates by Erik Simons and Ans Gorter. layout and some additional links for Europe (Netherlands), Africa, South America and Asia and some taxonomic databases.