There are not a lot of tree species that bloom in bright purple. There are some, though, and even a few that have fuzzy leaves. They are all tropical or subtropical trees that only thrive in hot climates except one. It can be grown in cold-winter climates but it is considered an invasive species in some locations.
Grewia occidentalis L.
Grewia occidentalis L., commonly known as cross-berry, four-corner or lavender star flower, is an evergreen shrubby tree that grows to a mature height of 3 to 6 m (10 to 20 feet). It is unlikely to grow anywhere in the British Isles other than the Scilly Isles. The star-shaped flowers are lavender to purple and 2.5 to 3.1 cm (1 to 1 1/4 inches) in diameter. They are produced in clusters throughout the summer. Its deep-green leaves are oval-shaped and slightly hairy. This tree also produces 2.5 cm (1 inch) diameter fruits that are yellow-orange when they form and gradually change to purple. Lavender star flower trees prefer organically rich soil that stays consistently moist but well-drained. Plant this tree in a sunny location that receives at least six to eight hours of direct sunlight each day.
Mundulea sericea, also referred to as cork bush, silver bush and Rhodesian silver-leaf, is a deciduous shrubby tree that is hardy in all of the UK except for the Northern Isles and Central Scotland. It can grow to a mature height of 7.5 m (25 feet). The 7.5 to 10 cm (3 to 4 inch) long leaves are pale green and covered with fine silvery hairs. A spring bloomer, this tree produces large flowers that are commonly bright violet, lilac, mauve or white. The flowers are followed by 10 cm (4 inch) long fuzzy seed pods that are yellow-brown at first but mature to brown-grey. These seed pods generally linger on the tree through the winter. Cork bush thrives in sandy and gravelly soil that drains well. Plant it where it will receive at least six to eight hours of direct sunlight each day.
Paulownia tomentosa or Princess-Tree is a deciduous tree that is hardy in all parts of the British Isles. Tomentosa is derived from the word tomentosum in reference to short downy fur or hairs. It grows quickly to a mature height and canopy width of 9 to 12 m (30 to 40 feet) usually, although it can grow to 15 m (50 feet). The fragrant bell-shaped flowers are bright lavender on the outside and pale blue or lavender on the inside. They are produced on 15 to 30 cm (6 to 12 inch) long panicles or clusters. Hairy flower buds form on the tree in the autumn, remaining throughout the winter to open in the spring. The fuzzy medium-green leaves can be up to 30 cm (12 inches) long. Oval-shaped woody seed pods also form on this tree in the autumn and remain throughout the winter. Princess-Tree can be planted in a sunny or partially shady location and is not particular about soil types. This tree is classified as invasive in some areas.
Tibouchina granulosa, commonly known as purple glory tree, is difficult to grow in the UK because it needs a warmer climate. It is technically an evergreen tree but it tends to be shrubby, requiring some pruning of lower branches when young to encourage a single-trunk tree form. Its oval-shaped dark green leaves are 10 to 20 cm (4 to 8 inches) long and covered with fine fuzz, giving them a velvety texture. This tree blooms predominantly from mid-spring to midwinter but will continue to bloom less profusely during the rest of the year. The 5 cm (2 inch) diameter five-petal flowers are bright purple and form in panicles or clusters at the branch ends. This tree is not particular about soil types as long it drains well but needs at least five hours of direct sunlight each day.