The tropical section of the greenhouse at Cambridge Botanical gardens contains many wonders, including a phenomenal example of the Jade vine (end of March), but packing a punch at this time of year (early March), due to its brilliant colour, is a red Powder Puff tree, Calliandra haemacephala. Who could resist such colour? I am seriously tempted to try to grow one just so I can touch the flowers freely.
Online information says that the seeds germinate easily after soaking, if you keep them in moist compost at temperatures of between 20° to 25°C. It might only take a couple of weeks for the first seedlings to appear! Another plus is that the plants are easily kept to a size that most suits your space (in fact they are good bonsai material). As far as I can see the only downside is the level of humidity that needs to be maintained.
Seeds are readily available. Chiltern Seeds have them at £3 for 15 seeds and Amazon have them for slightly more (promoting their bonsai use).
I remember having seen something very similar before whilst on holiday in France a few years ago. There was an eye-catching broad avenue of glossy, pinnate-leaved trees topped in candy pink and white fluffy pompoms. Obviously it’s a bit late to check now and there are ~140 species of Calliandra, but I dug out a photo and might have been Calliandra surinamensis: