From the leaves and characteristic shape of its flowers, I think this is a Radermachera although I do not know the species identity.The second small tree or big shrub with heart-shaped leaves is the Talipariti tiliaceum (synonym: Hibiscus tiliaceus; Family: Malvaceae), which is a back mangrove Hibiscus. The flowers last for only about a day and open yellow but gradually turn orange and then red. A link on this plant is shown below:
