Stock, Hussey, and Beckstrom, Cactus and Succulent Journal (U.S.) 86(2): 35, 2014
What is Opuntia diploursina?
O. diploursina grows to about 45 cm tall with upright branches of 1-4(6) cladodes. However, O. diploursina is often 20 cm tall. Cladodes are narrowly obovate to elloptic, 9-14 cm long, and 6-9 cm wide. As in O. polyacantha erinaceae and O. trichophora, the areoles are many and close together. Often there is one major spine per areole, especially in the second year. Spines are straw-colored or yellow-tan and flexible, 2-10 cm long. There are many minor spines appressed to the cladode surface and crossing over other areoles.
The yellow flowers are 6-7 cm long, but they can have a peach-colored cast to them due to a pinkish blush on many tepals. The style is white and the stigma is green. Filaments are white. Fruit is dry. There may be about 15 spines in each fruit areole–10 mm long or longer. The fruit is many seeded with propagules 9-10 mm in diameter with pronounced rims.
A major and important difference between O. polyacantha erinaceae and O. diplourisna is polidy. The former is tetraploid whereas the latter is diploid as is O. trichophora.
O. diplourina is related to O. trichophora. O. diplourisna differs from O. trichophora in being more upright, the presence of more minor spines that are more closely appressed to the cladode surface, and more and more flexible spines on the fruit.
The original authors proposed that O. diploursina represents an ancient diploid ancestor of O. polyacantha erinacea but did not elaborate. Hybrids between this Opuntia and O. basilaris and have been reported. Read the original description. O. diplourisna is diploid.
Permission to reproduce the original description was provided by the Cactus and Succulent Society Journal.