Mere colour is for unsophisticated lovers. A truly harmonious Valentine gift should smell beautiful as well. Sadly, commercial varieties of cut rose lack fragrance. This is because there is a trade-off between the energy that plants spend on making the complex, volatile chemicals that attract women and insects alike, and that available for making and maintaining pretty-coloured petals. So, by artificially selecting big, long-lasting flowers, breeders have all but erased another desirable characteristic.

The author of this article does a great job of making the science accessible to the general reader.