Lactiflora Cultivars vs. Herbaceous hybrids
Historically, most varieties of peony sold were cultivars of P. lactiflora. However, these varieties often didn't have strong enough stems to hold the large blossoms upright. As a result, most of the lactiflora cultivars needed staking. In response to this, the newer herbaceous hybrid peonies were developed. These have stronger stems, so that staking isn't needed. However, herbaceous hybrids aren't floriferous; that is, they usually don't have side buds — they typically produce only one bud per stem.
Examples of Paeonia lactiflora varieties: Angel Cheeks, Ann Cousins, Attar of Roses, Big Ben, Bowl of Beauty, Bowl of Cream, Bu-te, Butter Bowl, Charlie's White, Doreen, Dr. Alexander Fleming, Duchesse de Nemours, Edulis Superba, Elsa Sass, Fairy's Petticoat, Fancy Nancy, Félix Crousse, Festiva Maxima, Gardenia, Gay Paree, Gilbert H. Wild, Hermione, Kansas, Krinkled White, Lady Alexandra Duff, Le Charme, Maestro, Miss America, Mister Ed, Monsieur Jules Elie, Mother's Choice, Mrs. Edward Harding, Mrs. Euclid Snow, Mrs. Franklin D. Roosevelt, Myrtle Gentry, Nippon Beauty, Paul M. Wild, Princess Margaret, Raspberry Sundae, Sarah Bernhardt, Sea Shell, Shirley Temple, Sword Dance, Top Brass, Tourangelle, Westerner, White Sands.
Examples of herbaceous hybrids: Athena, Blaze, Buckeye Belle, Claire de Lune, Coral Charm, Coral 'n Gold, Dandy Dan, Early Scout, Etched Salmon, Flame, Henry Bockstoce, Mahogany, Many Happy Returns, Paula Fay, Pink Hawaiian Coral, Red Charm, Red Red Rose, Roselette, Roy Pehrson's Best Yellow, Scarlett O'Hara, Showgirl, Walter Mains.
Cultivars of Paeonia lactiflora are often referred to as "Chinese peony", "garden peony", "bush peony", or "herbaceous peony" (the names are used interchangeably in catalogues). Strictly speaking, the term "herbaceous" means that the plant dies down in the fall, and new growth comes up in spring. This is true for most species of the Paeonia genus. It is NOT true, however, for the species which is normally called the Tree Peony.