Other cultivars/Species:  Many, many are in the Botanical Garden’s Dahlia Garden.
Extra notes and interesting information:  ‘Santa Claus’, originated in 1983 by the late Harold Miller, a charter member of the Puget Sound Dahlia Association.  This small, informal decorative bicolor dahlia is popular due to its unique form and color. 
Dahlia Growing Tips from http://www.dahlia.org
Dahlias can be started from dormant tuberous roots, grown from seeds, rooted from cuttings, or purchased as transplants. Because dahlias are hybrids, plants grown from seeds do not completely grow true to type.
Dividing: Dahlia tuberous roots should be divided before they are planted in the spring. The best time to divide is after the eyes have sprouted and the new growth is no more than an inch in length. Cut the clump into individual tuberous roots with a sharp knife. Each tuberous root must have at least one eye (growing point) or sprout to produce a new plant. Eyes are found where the tuberous root and the stalk of last season's plant join.
Planting: Dahlias are very sensitive to freezing temperatures. Large tuberous roots may be planted about 2 weeks before the last spring frost date. Small tuberous roots and transplants should not be planted until all danger from frost has passed.
When plants are about a foot tall and display 3 to 4 pairs of leaves, pinch out the terminal shoot to encourage branching.  Flower size can be increased by removing lateral flower buds (referred to as disbudding). When the three buds that form at the end of each branch reach the size of small peas, remove the two side buds. Small-flowering types should not be disbudded.