Article from Bean's Trees and Shrubs Hardy in the British Isles
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'Pentactina' from the website Trees and Shrubs Online (treesandshrubsonline.
The species described below is the only member of this genus, which is allied to Spiraea but differs from it in its linear petals and its carpels with only two ovules. The inflorescence resembles that of Stephanandra, which genus differs in having stipules.