I'm not very clued up on Welsh flower names but here are some random names. Some of them are the Welsh for English names and some are Welsh words.
Glaw -
RainAfanen - Raspberry
Plyg Hwyl - Reef
Celyn -
HollyAfon -
RiverRhosyn -
RosePaderau - Rosary
Blodeuyn - Flower
Tiwlip - Tulip
Briallen - Primrose
Croeso Haf -
HyacinthCenhinen Bedr - Daffodil
Llygad -
DaisyDisgleirio - Dazzle
Grwn - Ridge
Rhamantus - Romantic
Adda -
AdamAnghrist - Antichrist
Andreas -
AndrewBartholomeus -
BartholomewBeda - Bede
Bedwyr - Bedievre
Awstin -
AugustineBeti, Betsan, Betsi -
Betty , Betsi
Buddug - Boadicea;
VictoriaBwda - Buddha
Cadi -
Catherine ;
KateCadog, Catwg - Cadoc
Cai -
KayCaradog - Caratacos, Caractacus
Caswollon - Cassivellanus
Catrin -
CatherineCesar -
CaesarCrist - Christ
Cystennin -
ConstantineDafydd ,
Dewi -
DavidEdmwnt, Emwnt -
EdmundEfa -
EveElen -
Helen ,
EllenEleias -
Elijah ,
EliasEliseus -
Elisha , Elliseus
Emrys -
AmbroseErcwlff -
HerculesEsay, Esesia -
IsaiahEsyllt -
IseultFychan -
VaughanFysil, Fferyll -
VirgilFfowc - Foulkes
Ffraid - Bride,
BridgetGarmon - Germanus
Geraint -
GerontiusGerallt -
GeraldGlyndowr - Glendower
Gruffudd ,
Gruffydd -
GriffithGwallter -
WalterGwener -
VenusGwenffrewi, Gwenfrewi -
WinifredGwenhwyfar -
GuinevereGwilym -
WilliamGwladus -
GladysGwrtheyrn - Vortigern
Harri -
Harry ,
HenryHoras -
HoraceHors -
HorsaHu,
Huw -
HughIago -
JamesIau - Jove,
JupiterIesu Grist -
Jesus Christ
Ieuan -
EvanIoan -
JohnIorwerth -
EdwardIwan -
JohnLowri -
LauraLuc -
LukeLleucu -
LucyLlwyd -
LloydLlyr - Lear
Mabli -
MabelMair -
MaryMali -
MollyMallt -
Maud ,
MatildaMarc -
MarkMarged, Margred -
MargaretMari -
MaryMawrth - Mars/March
Mercher -
MercuryMererid -
MargaretMeurig -
MorrisMihangel -
MichaelModlen, Magdalen -
MagdaleneMyrddin -
MerlinNeifion -
NeptuneOfydd -
OvidOswallt -
OswaldOwain -
OwenPadrig -
PatrickPedr -
PeterPeredur - Perceval
Prys - Price, Preece
Puw - Pugh
Pyrs -
PierceRheinallt -
ReginaldRhisiart -
RichardRhobert -
RobertRhonwen -
RowenaRhydderch -
RoderickRhys -
Rees , Rice
Sadwrn -
SaturnSebedeus -
ZebedeeSelyf -
SolomonSian -
JaneSiarl -
CharlesSiarlymaen - Charlemagne
Sieffre -
GeoffreySiencyn - Jenkin
Sion -
JohnSioned -
JanetSior, Siors -
GeorgeSteffan -
StephanTimotheus -
TimothyTomos -
ThomasTudur - Tudor
Twm -
TomWmffre -
HumphreyHeulog - Solar
Haul - Sun
Derwen - Oak