Hesperaloe (false yucca) is a genus of flowering plants in the family Asparagaceae, subfamily Agavoideae.
 It contains perennial yucca-like plants with long, narrow leaves produced in a basal rosette and flowers borne on long panicles or racemes.
 The species are native to the arid parts of Texas in the United States and Mexico and are sometimes cultivated as xerophytic ornamental plants.
The ancient Greek drama was a theatrical culture that flourished in ancient Greece from c. 700 BC.
 The city-state of Athens, which became a significant cultural, political, and military power during this period, was its center, where it was institutionalised as part of a festival called the Dionysia, which honoured the god Dionysus.
 Tragedy (late 500 BC), comedy (490 BC), and the satyr play were the three dramatic genres to emerge there.
 Athens exported the festival to its numerous colonies and allies in order to promote a common cultural identity.
Helen (Ancient Greek: Ἑλένη , "Helenē") is a drama by Euripides about Helen, first produced in 412 BC for the Dionysia in a trilogy that also contained Euripides' lost "Andromeda".
 The play has much in common with "Iphigenia in Tauris", one of the playwright's later works.
Dionysia is a genus containing 49 species of flowering plants in the family Primulaceae.
 They are small, cushion-forming alpines native to mountains in central Asia.
 They are usually evergreen perennials with felted leaves, covered with bright yellow or pink, five-petalled flowers in spring.
 They are often difficult to cultivate if the correct conditions are not provided.

Question: What do Dionysia and Hesperaloe have in common?
Answer: flowering plants