Puna bonnieae is native to Argentina Northwest where the plant grows on rocky soil in the puna community vegetation and can spread up to 3300 m of altitude.
Puna bonnieae is an uncommon succulent belonging to the Cactaceae botanical family. The cactus is sometimes classified in Opuntia genus although it doesn’t resemble an Opuntia. The plant is a small geophytic cactus which grows in dense clumps and it hides underground during drought periods. The stem is greyish-green, thin, ball-shaped and emerge from the ground for few centimetres and can form large tufts with more than 100 heads. The stem if exposed to the direct sun can change color and can take on deep purple color. The roots are tuberous and deep, specialized to withstand to the drought. The leaves are very small and fall off early. The areoles are closely set and bear the glochids in the lower part and spines in the upper part of the stem. The glochids are short spines, barbered at the tip, extremely hurtful and a characteristic, only of the subfamily, Opuntioideae, of the family Cactaceae. The 9-20 radial spines are short, reddish to brown, flat, radiating and bent over the stem. Blooming occurs during the summer and the blossoms are borne at the apex of the plant. The flowers are small, light pink with yellow central stamens, 2-3 cm in diameter, very showy. The flowering is diurnal and last few days. Although the plant is slow growing it tends to proliferate more than the type species both in habitat and culture.
The plant has a slow growth rate but it is easy to cultivate. The plant needs a full light sun exposure but is recommended to avoid direct sun-light during the summer. Long exposure to direct sun-light can cause burns and burnt spots. The maximum resistance to cold is 5 °C so it is recommended not to expose the plant to lower temperatures. Too low temperatures can cause the stem or leaves to break due to water freezing inside the tissues. Temperatures between 10 and 15 °C allow the plants to enter vegetative rest which is essential for the flowering of the following year. Plants should not be placed inside the house where average temperatures of 20 degrees prevent vegetative rest. The soil should be a well-draining and porous soil, so you can use a standard cactus soil or a mix of fertile soil and sand. The pumice should always be placed on the bottom of the pot. Remember to use a perforating pot to drain excess water. Watering can be done regularly during the vegetative period. During the vegetative period you can water the plant every 5 days with half a glass of water, checking that the soil is completely dry before watering again; in winter you should stop the watering to allow the plant to enter dormancy. Decrease the amount of water if the plant is kept indoors or if the pot is smaller than 12 cm. The plant is used to growing in poor soils, for this reason it does not need abundant fertilization, it is sufficient to fertilize once in spring and once in summer. If the pot starts to be too small for the plant you can repot the plant in a pot 2 cm wider. Repotting should be done early in the growing season with fresh new potting soil; it is usually done every 3-4 years. Be careful to red spiders and mealy bugs.
Propagation can be done by cutting or by grafting. By cutting you can make the cut during the spring and then let the cutting dry; after a few days the cut surface will dry and a callus will form, then place the cutting in a mixture of sand, soil and pumice. To increase the success of propagation you can make two or more cuttings at the same time. It is advisable to use rooting hormone at the base of the cut to energize root development. For cuttings it is recommended temperatures around 20 °C. By grafting make the cut as close to the growing tip as possible, then chose a stock with a diameter similar to that of the scion. After the cut, wash away the latex until it no longer remains. Bring the scion closer to the stock and held together with elastic bands. The plants should be left in an airy and shady place for 7-10 days before the bands are removed.
It takes its name from a plateau located between Argentina and Bolivia, the place of origin of this species.
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