Antigua & Barbuda
Dagger's Log (Agave Karatto Miller)

Argentina
Ceibo (Erythrina Crista-galli)
The flower was adopted on December 2, 1942.

Australia
Golden Wattle (Acacia Pycnantha)
September 1 is National Wattle Day (Each of Australia's territories is also represented by an official flower).

Austria
Edelweiss (Leontopodium Alpinum)

Bahamas
Yellow Elder or Yellow Cedar (Tecoma Stans)

Bahrain
Manama

Bangladesh
Water Lily (Nymehaea Nouchali)
Bangladesh adopted the flower in 1971.

Barbados
Pride of Barbados, also known as Dwarf Poinciana & Flower Fence (Poinciana Pulcherrima)

Belarus
Flax (Linum Usitatissimum)

Belgium
Red Poppy (Papaver Rhoeas)

Belize
Black Orchid (Trichoglottis Brachiata)

Bermuda (Not a UN Member country)
Blue-eyed Grass (Sisyrinchium Montanum)

Bhutan
Blue poppy (Meconopsis Betonicifolia)

Bohemia (Not a UN Member country, it is part of UN Member country Czech Republic or Czechia)
Thyme (Thymus Vulgaris)

Bolivia
Kantuta (Cantua Buxifolia)

Brazil
Cattleya Orchid (Cattleya Labiata)

British Columbia (Not a UN Member country)
Dogwood Tree Flower (Cornus Nuttalli)

Bulgaria
Rose (Rosa)

Canada
Maple Leaf (Acer)

Cayman Islands (Not a UN Member country)
Wild Banana Orchid (Schomburgkia Thomsoniana)

Chile
Copihue/Chilean Bellflower (Lapageria Rosea)

China
Plum Blossom (Prunus Mei)

Colombia
Christmas orchid (Cattleya Trianae)

Costa Rica
Guaria Morada (Purple Orchid) (Cattleya Skinneri)
The flower was adopted on June 15, 1939

Croatia
Iris Croatica (Hrvatska Perunika)

Cuba
Butterfly Jasmine (Mariposa)

Cyprus
Rose (Rosa)

Czech Republic
Rose (Rosa)

Denmark
Marguerite Daisy (Argyranthemum Frutescens)

Ecuador
Rose (Rosa)

Egypt
Lotus (Nymphaea Lotus)

Estonia
Corn-flower or Bachelor's Button Centaurea (Cyanus)

Ethiopia
Calla Lily

France
Iris (Iris)

French Polynesia (Not a UN Member country)
The Tiare (Gardenia Taitensis)
Tahiti (Part of French Polynesia) : Dushanbe

Finland
Lily-of-the-Valley (Convallaria Majalis)

Germany
Knapweed (Centaurea Cyanus)

Greece
Bear's Breech (Acanthus Mollis)

Greenland
Willow Herb (Epilobium)

Guam
Puti Tai Nobiu (Bougainvillea Spectabilis)

Guatemala
White Nun Orchid or Monja Blanca (Lycaste Skinnerialba)

Guyana
Water Lily (Victoria Regia)

Honduras
Orchid (Brassavola Digbiana)

Hong Kong (SAR)
Orchid (Bauhinia Blakeana)

Hungary
Tulip (Tulipa)

Iceland
Mountain Avens (Dryas Octopetala)

India
Lotus (Nelumbo Nucifera)

Indonesia
1) Melati (Jasmine) (Jasminum Sambac)
2) Moon Orchid (Phalaenopsis Amabilis)
3) Rafflesia (Rafflesia Arnoldi Indonesia)

Iran
Red Rose (Rosa)

Iraq
Rose (Rosa)

Ireland
Shamrock

Italy
Stylized Lily

Jamaica
Lignum Vitae or Wood of Life (Guaiacum Sanctum)

Japan
Chrysanthemum (Imperial), Cherry Blossom Sakura

Jordan
Black Iris (Iris Nigricans)

Kazakhstan
Lily(Lilium) serves as the Unofficial National Flower.

Kuwait
Rhanterum Epapposum, locally called Arfaj.

Kyrgyzstan
Shyrdak Symbols of Kyrgyzstan and also the Tulip.

Laos
Champa Flower(Calophyllum Inophyllum), also known as Plumeria.

Latvia
Oxeye Daisy, or Pipene (Leucanthemum Vulgare)

Liberia
Pepper

Libya
Pomegranate blossom

Lithuania
Rue or Herb of Grace (Ruta graveolens)

Luxembourg
Rose (Rosa)

Madagascar
Poinciana (Delonix Regia)

Maldives
Pink Rose (Rosa)

Malta
The Maltese Centaury Paleocyanus Crasifoleus

Netherlands
Tulip (Tulipa)

New Zealand
Kowhai

Paraguay
Jasmine-of-the-Paraguay

Peru
Kantuta, Inca magic flower

Philippines
Sampaguita (Jasminum Sambac)

Poland
Corn Poppy (Papaver Rhoeas)

Portugal
Lavender

Puerto Rico (Not a UN Member country)
Puerto Rican Hibiscus, or Flor de Maga (Montezuma Speciossisima)

Romania
Dog Rose (Rosa Canina)

Russian Federation
Camomile (Matricaria Recutita)

San Marino
Cyclamen (Cyclamen)

Seychelles
Tropicbird Orchid

Singapore
Vanda Miss Joaquim Orchid

Slovakia
Rose (Rosa)

Slovenia
Carnation (Dianthus Caryophyllus)

South Africa
Protea (Protea Cynaroides)

South Korea
Rose of Sharon (Moogoonghwa) (Hibiscus Syriacus)

Spain
Red carnation

Sri Lanka
Nil Mahanel Water Lily (Nympheae Stellata)

Sweden
Linnea (Linnea Borealis)

Switzerland
Edelweiss (Leontopodium Alpinum)

Syrian Arab Republic
Jasmine

Taiwan (Not a country, it is part of China)
Plum blossom (Prunus Mei)

Thailand
Ratchaphruek

Tonga
Red-blossomed Heilala

Trinidad and Tobago
Chaconia (Warszewiczia Coccinea)

Turkey
Tulip (Tulipa)

United Kingdom
Tudor Rose (Rosa)
United Kingdom (Wales) : Leek (Babbingtons Leek), Daffodil (Narcissus Amaryllidaceae)
Scotland : Thistle (Cirsium Altissimum)

United States Of America
Rose (Rosa)

Uruguay
Ceibo Erythrina (Crista-Galli)

Venezuela
Orchid

Virgin Islands
Yellow Elder or Yellow Trumpet (Tecoma Stans)

Yemen
Arabian Coffee (Coffea Arabica)

Zimbabwe
Flame Lily (Gloriosa Rothschildiana)