Ocotillo, oleander, oncidium, orchid and oxalis are plants. They begin with the letter o.
orange
oak tree
I don't know that's why I am looking
Open Hearth day lily
Some words that start with the letter O are:oceanOddOdeofoffOfficeogreoldOliveOnoneOpalOppositeorOrangeorboreganoorganismorgasmorigamiotherotteroughtOxymoronoval
orange rose
Ohio
Ozymandias
okra
Some happy words that start with O include: Overjoyed Optimistic Open-hearted
Some German words that start with the letter O are Opa, Oma and oberflächlich.
Thyme and Tomato are plants. Thistle is a plant.