Lavender is a flowering plant in the mint family. Its aroma has been shown in human studies "to slow down heart rate, slow blood pressure and put you in a parasympathetic state, which is a relaxed state," says University of Miami School of Medicine scientist Tiffany Field, who has studied the effects of lavender on relaxation and sleep.
Acacia baileyana cheers up winter. Its feathery purple and olive leaves and profuse flowers make it a really happy plant (to 7 m when mature) to have around in the middle of wintery July. Said to flower in spring, it has been flowering in July here (south) for a number of years. Even though it's a NSW native and is invasive outside of its normal range, its pleasant form makes it a good screen from neighbours.