Peraphyllum is a monotypic genus of flowering plants in the rose family, containing the single species Peraphyllum ramosissimum, commonly known as the squaw apple or wild crab apple.
Alkanna is a genus of herbaceous plants including about 60 species of the family Boraginaceae.
Pentaglottis sempervirens, the green alkanet, evergreen bugloss or alkanet, is a bristly, perennial plant native to Western Europe.
 It grows to approximately 60 cm (24") to 90 cm (36"), usually in damp or shaded places and often close to buildings.
 It has brilliant blue flowers, and retains its green leaves through the winter.
 The plant has difficulty growing in acidic soil (it is calcicolous).
 The name "alkanet" is also used for dyer's bugloss ("Alkanna tinctoria") and common bugloss ("Anchusa officinalis").
 Green Alkanet is an introduced species in the British Isles, meaning it is not native.

Question: What do both Peraphyllum and Alkanna have in common?
Answer: plants