Idk about other maps but like everyone says, go to the swamp and bring your self a tickle chicken aka theri and if on mobile the swipe up using the finer gathering attack and it will give loads of rare flower AND plant species x
If you eat a rare flower near wild dinos, they will become aggressive towards you for a period of time, as well as anything you meet along the way. Avoid doing so unintentionally, however this can become useful if you need to grab a dinos attention for taming or to lead it somewhere.
Tame up a therizinosuar and bring it to the swamp, you’ll end up getting a great amount really fast. My rates were at 3.2 harvest damage & 5.0 Harvest amount & in mere seconds i had over 1.3K rare flowers
To the person who said “ Plz eat them near a giga or a Titananboa and they will be tamed” dude those will chase you until you die so don’t listen to that person. My brother listened to him and he died far from his base with his best tame.