I'd go with Victorian. Not sure how in depth your assignment has to be but the Victorian Head-Gardener was also the florist of the house (though he rarely got his hands dirty). Neighbouring house's gardeners would compete with each other raising new hybrids (often naming them after the familys they worked for). The houses and dining tables were awash with flowers (and other clutter!) so pictorial evidence should be realitively easy to find and the display you make could be very lavish! Also, the Victorians were the explorers so it was during this era that we found and started to import most of our non-native plants and flowers (and fruits and...)

The era is just so rich in change that i would think it would be relatively easy to find a theme to lose yourself in.

Just my tuppence - i'm sure all the others are as good - victorian britain simply fasinates me.

Susie
p.s. I have a Victorian timeline i did (major events year by year) - if you would like a copy pm me.