Simplify the following text for a Grade 5 native English-speaking person.
Original: They are slow-growing evergreen shrubs or short trees , from 2.5 t tall , with sparse branches , sometimes bearing small thorns .
Simplified: Kumquats are slow-growing , evergreen shrubs or small trees , from 2.5 â `` 4.5 m tall , with dense branches . Sometimes they have small thorns .