Iris
Idesia
Inula
Iresine
Ixia
Indigo
Here are some flowers that begin with the letter G:GaillardiaGardeniaGazaniaGentianGeraldton WaxGeraniumGerberaGerbera DaisyGermander SpeedwellGermaniumGilly FlowerGladiolaGladiolusGlobeflowerGloxiniaGodetiaGoldenrodGrevilleaGumamelaGuzmaniaGypsophilaGypsophilla
Here are some flowers that begin with the letter Q:Quaker lady irisQueen Anne's LaceQuamashQueen Fabiola lily
Magnolia, marigold, morning glory and mums are flowers. They begin with the letter M.
Umbrella plant, urginea and ursinia are flowers. They begin with the letter U.
Here are some flowers that begin with the letter S:SafflowerSagittariaSaintpauliaSalixSalviaSanguinariaSansevieriaSantolinaSaponariaSarraceniaSaxifragaScabiosaScillaSea lavenderSedumShasta daisyShell flowersSnapdragonSnowballSoldasterSolidagoSolidasterSpider lilySpider mumsStachysStanhopeaStaticeStephanotisStreptocarpusSunflowerSweet peaSword fern
azalea
The venusflower
Anemone, aster.
snowball
sabatia angularis
naked ladies
violet is my only answer.