Overheated Gaura

Stinking hot day today - so hot that even the hardy flowers of the Gaura plant refuse to fully open their petals. The flowers themselves are not actually drooping, but it seems the furtherest the petals are prepared to go in this heat is about half open.
They're native to the US (especially Southern Louisiana and Texas), and are renowned for thriving in the hot, dry conditions found in Australia - hello suburban Adelaide - even during drought. But on such a scorcher of a day, these Gaura lindheimeri are very sensibly preserving valuable moisture by keeping their petals partly furled. (Or should that be partly unfurled?)
Commonly known as Lindheimer's Beeblossom, Pink Gaura (also comes in White Gaura), Lindheimer's Clockweed and Indian Feather, their long thin stems don't grow from your conventional roots, but more from your  underground rhizome. 
Which helps explain their drought tolerance. It also helps explain why several species are classified as noxious weeds - due to their canny dual traits of invasiveness and hardiness, large clumps of them can literally shade out other species of plants.
As payback for a plant with such stunning-looking flowers being classified as a weed, there's no effective biological control method available. If they start to take over your garden - which they can easily do - you're expected to manually pull out each and every plant that's surplus to requirements. And even then, you often can't avoid leaving scraps of rhizome material in the ground, which immediately start generating more growth.
So a bit like our democratic freedoms, the price you have to pay for the Gaura's gorgeous flowers in your garden is eternal vigilance.