These unique, double-bloomed flowers add dazzling interest to landscapes and cut-flower arrangements. Plant heights range from a low of 12" for some compact varieties up to 6' for certain towering giants. The flowers are generally large with petals that are broad, flat tipped, occasionally wavy and form no visible central disc. There are two classifications of decorative dahlias: formal and informal. Formal varieties have flat petals that are evenly and uniformly distributed throughout each bloom. The flowers produced by informal varieties have irregularly arranged petals that are mostly flat with slightly rolled tips.