Cassia bicapsularis

Winter Cassia, also known as Senna (Cassia bicapsularis) is a real wonder this time of year. The rest of the year this shrub is nothing but lush green foliage but by late November it is usually dripping with brilliant yellow blooms.

Cassias are host to a variety of sulphur butterflies and we have several species in the gardens including Desert Cassia (Cassia polyphylla) , Partridge Pea (Chamaecrista fasciculata), Candlestick Cassia (Senna alata), Sicklepod Senna (Cassia obtusifolius), and Winter Cassia to help draw as many butterflies as possible.

Cassias are vigorous plants that grow rapidly and can become quite unruly, so expect a great deal of pruning if you want to keep this shrub anywhere near dainty. This particular species of cassia is native to South America, but there are plenty of Florida native species around if you prefer gardening with local plants. This variety of cassia makes an excellent host plant since its very quick growth helps it to recover rapidly from any damage feeding caterpillars may cause.

Although most sulphur caterpillars are usually green in color, when the fall and winter caterpillars of species like the Orange Barred Sulphur (Phoebis philea) pictured to the right [Photo: What's That Bug] dine upon the bright yellow cassia flowers, they also turn yellow. If the caterpillar resumes eating the green leaves of cassia, then they will turn back to green in color within a day or two.

I have noticed that larvae, when given the option, will consume the flowers and unopened flower buds before they will eat cassia leaves. I can only assume that the flowers are somehow more tasty to their delicate caterpillar pallets. At this time of year the larvae of sulphur butterflies are much easier to find as their screaming yellow color really helps my eye to pick them out on the sprawling cassia shrubs.