Given the reference text about the genus Banksia, tell me how many species of Banksia there are and what size they can grow to.

Banksia is a genus of around 170 species in the plant family Proteaceae. These Australian wildflowers and popular garden plants are easily recognised by their characteristic flower spikes, and fruiting "cones" and heads. Banksias range in size from prostrate woody shrubs to trees up to 30 metres (100 ft) tall. They are found in a wide variety of landscapes: sclerophyll forest, (occasionally) rainforest, shrubland, and some more arid landscapes, though not in Australia's deserts.

There are around 170 species of Banksia. Banksias range in size from prostrate woody shrubs to trees up to 30 metres (100 ft) tall.