When Roots and Shoots started in 1982 there was just one white lilac on the site. That has gone I'm afraid - but as you can imagine after 30-odd years there have been many, many celebratory as well as routine bouts of planting.
The trees of Roots and Shoots that David uses regularly as structure for visits by school and other groups, featured in the 30th Anniversary Annual Review in 2012 as a double page spread and the oak is on the rear cover of the latest, 2015 Annual Review (click on images at bottom to see slide show).
The plants in the Wildlife Garden are a mixture of native and exotic: this is London and the only real requirement is that any choice for a new plant should "be good for bees". The Paradise Corner, for example, being ultra-sheltered and south facing grows pomegranates and Brazilian Pineapple Guava (Acca sellowiana or 'Feijoa'). The towering Echium pininana from the Canary Islands which is allowed to more or less rampage across the site provides 5m of bee forage (bumbles, honey and solitary bees) in each plant! The meadows, though, are almost entirely native and the pond plants entirely so.
Around the main building are the mimosa trees, the quince by the Natural Roots Building, beds with changing plantings, bulbs and other shade tolerant plants beneath the Walnut and a multitude of containers and planters.