For an alphabetical listing of plants beginning with each letter of the alphabet, have a look at: http://en.wikipedia.org/wiki/List_of_garden_plants Thats one way of making wikianswers redundant.
Snapdragon, Soldaster and Sweet Pea are flowers. They begin with the letter S.
SalviaSabi StarSand_VerbenaSarraceniaSatin_PoppyScarlet_PlumeScorpion_SennaSea_LavenderShaddockShamrocksShasta_DaisySnap_DragonsSnow_DropSnow_FlowerSowbreadSpear_LilySpider_LilySpoon_LilySpurgeStar_of_the_VeldtSummer_HyacinthSunflowerSwamp_DaisySwamp_HibiscusSwamp_LilySweet_MarySweet_SultanSweet_WilliamSyringa
Sweet pea, sunflower, salvia, snowball and snapdragon are flowers. They begin with the letter S.
Scabious can be white
Salvia, snapdragon, snowball, soldaster, statice, stephanotis, sunflower and sweet pea are flowers.
Sweet Pea and Salvia are flowers. Soldaster is a flower.
Yes, the Sunflower.
snowball
sillyablesquashsweeny toddsprinkle hairspace macers
sabatia angularis
Some three letter words that start with S are: sadsagsapsatsawsaxsayseaseesetsewsexsheshysicsinsipsirsissitsixslyskisobsodsonsotsowsoyspystysubsumsunsup
Here are some flowers that begin with the letter S:SafflowerSagittariaSaintpauliaSalixSalviaSanguinariaSansevieriaSantolinaSaponariaSarraceniaSaxifragaScabiosaScillaSea lavenderSedumShasta daisyShell flowersSnapdragonSnowballSoldasterSolidagoSolidasterSpider lilySpider mumsStachysStanhopeaStaticeStephanotisStreptocarpusSunflowerSweet peaSword fern