The mistletoe, held sacred in Druid cultures, state flower of Oklahoma, beneath whose branches lovers kiss—a parasite, but an ingenious one: its life cycle closely attuned to the life of its host tree and various bird species, its seeds are glued to the host branch by some, ingested but not digested by others, broadcast and then pruned, while the host tree lures the vine with its sap, then produces tannin to kill or stunt the vine’s growth. The program also shows the extraordinary adaptation of an underground parasitic orchid, whose corolla is flush with the ground, and the strangler fig, which doesn’t feed on the sap of the host but uses it as a support until the host has been choked to death. (28 minutes)