It’s senna time again, and our roadsides are lively with bright splashes of yellow.
These plants were in flower on the Oakey Cooyar Road last weekend.
If you drive past without looking closely, you might think you were seeing wattles. A closer look will tell you that these pretty plants have cassia-type flowers.
Despite its name, this is not just a plant of deserts, but is quite at home in the drier parts of Toowoomba region. It lives up to its name when it comes to its water needs, though. It is a very drought hardy plant, never needing watering once established
Australia has 46 of the world’s 350 Senna species. Alas we also have a few extras, including the weedy Easter cassia, Senna pendula, which is a native of tropical America. It is it has put some people off growing sennas at all, which is a pity. Our natives are very civilised plants, usually growing to not much more than waist high, and of course, by definition, local native plants can't become feral weeds!
Sennas are not long lived plants. They tend to need replacing every 5 - 10 years, which is easy enough to do as they are simple to grow from seed. Look for them in November. In nature a fire, followed by rain, results in a flush of new plants. You can imitate this by using the boiling water method to get them started. (Put them in a coffee cup. Pour boiling water on. Leave to cool overnight. Plant.)
They may also self-seed for you if you live in their home territory, as older seed can germinate without fire.
Like all Sennas, they are butterfly host plants, attracting several different species of yellow butterflies to breed.
