Trout
Some words that start with the letters tr:tracetracktradetrailtraintramptraptrashtraveltraytreadmilltreattreetrendtriadtrialtribetricktricycletriptripodtrolleytrooptrophytrouserstrucetrucktruetrulytrumptrusttruth
IrisImpatiensIpomoeaIxia
If you mean "U", there are 0 flowers that start with "U".
orchid
Runuculus
Aspidistra.
rose
violet
Tagetes.
Some flowers that start with the letter "P" include peonies, pansies, poppies, and petunias.
Jasmine and Jupiter's beard are flowers.