The first is Senna bicapsularis (syn. Cassia bicapsularis) with the common names of Christmas senna, winter cassia and fall cassia, all indicating that this is the time of year when they are at their peak of blooming. Fall cassia can be kept pruned into a tall shrub or can be let loose to form a small tree (10-12 feet). Right down the street from me on 11th Avenue in Mount Dora are a couple of fall cassias that have been planted to beautiful effect behind a white fence:
Fall cassia is a host plant for a number of sulphur butterfly caterpillars. These butterflies usually zoom through the yard without stopping, but will stop to lay eggs and perhaps stick around for a bit of nectar from one of your nectar plants. Pictured is a female sulphur laying an egg:
The second plant with great fall color is our native firebush (Hamelia patens) with its orange flowers and black berries. Firebush gets to be a tall shrub and can be grown in either full sun or partial shade. It is a favorite nectar plant of the two passionvine butterflies in our area: the gulf fritillary and the zebra longwing.