Opuntia

Opuntia is the largest group of Cacti with over 360 species ranging from Canada to Chile and Argentina. This group also includes several edible kinds. These plants are commonly known as Bunny Ears, Cholla, Prickly Pear, Barbary Fig, Tuna and Indian Fig. Opuntia is usually separated into two groups. The first group is Platyopuntia; those belonging to this group have round flattened joints, called pads. They are commonly known as Prickly Pears because they produce the spiny, usually edible, fruits. Some are grown for their edible pads called nopales or nopalitos. The spines of these pads must be singed off before they can be prepared for eating. The second group is Cylindropuntia; those belonging to this group have long, cylindrical joints and are commonly called Chollas. The sizes of Opuntias vary. They can be just a few inches and spreading, or grow 100 feet high and tree-like. Most kinds of these plants are covered with sharp, barbed spines that are difficult to remove without lacerating the skin. An interesting characteristic of these plants is the glochids. These are small, barbed spines produced at the base of the large spines. They can be very irritating if not handled carefully. The flowers, which are borne from spring to fall, are shaped like cups or saucers. They are produced singly on the upper parts of the joints. They have many petals and they average 3 inches in diameter. They are usually yellow but can come in purple, orange or red. O. lindheimeri is a pretty variety that grows up to 4 feet high with a spread of up to 10 feet. This spreading plant grows only two or three pads high. The pads are covered with cushions of golden brown glochids. In the summer, bright orange or dark red flowers are produced at the edges of the pads; these are followed by purple fruits. O. tunicata is an interesting plant that grows up to 3 feet high with a spread of 6 feet. Young plants have few spines, but older plants are densely covered in barbed spines that have a silvery radiance in bright light. In the summer, gold to pink flowers and greenish-yellow fruits decorate this plant. O. microdasys is a spineless variety, though it is covered with tufts of irritating, barbed glochids. The flowers of this plant and its varieties are ordinarily yellow.

Pot Cultivation

These plants require a minimum temperature of 50� F. When growing these plants indoors, they should have a soil mixture of two parts of sandy loam, one part of broken brick and one part of sand. Repotting doesn't need to be done every year; in fact, they can remain in the same pots for several years. Only if the soil is worn out or the plants stop growing well does it become necessary to repot in March or April. Remove the crocks and loose soil from the roots and plant them in slightly larger pots if their roots are healthy and abundant; if they have a small root system, then pot them in pots just large enough to hold them without crowding. The soil shouldn't be watered until it becomes dry, then soak it and wait for it to dry again before watering. Repeat this until the pots fill up with roots and then just keep the soil moist throughout the summer. During the winter, the soil is only soaked once in a while, just enough to keep the stems from shriveling. Plants growing in a home rather than a cool greenhouse may need a little more water since the temperature is a little warmer. Shading isn't required but good ventilation at all times is. In the summer, Opuntias growing in pots can be set outside. In mild, semi-desert or desert regions, Opuntias grow wild easily and unless they're controlled, can become serious pests. Some of these plants spread quickly, a tiny piece of stem that comes into contact with soil will take root and their seeds, which are spread by birds, germinate rapidly. In some countries where they have been introduced, such as Australia, they have covered large areas and become a pain to farmers who find it difficult to get rid of them. In the northern United States, O. compressa may be grown outside in well-drained soil especially when it's sandy soil near the sea. Other hardy varieties can be grown in a well-prepared bed that has excellent drainage against a south-facing wall. It's good to have the bed raised a few inches above the surrounding ground. In the winter, it would be beneficial to protect them by covering them with glass, cold-frame sash, or some similar device. The fruits of the Prickly Pears usually turn dark red when they are ready to be harvested. They are sweet and juicy when ready. If there is threat of frost, pick fruits a bit early and ripen indoors. Pads can be singed, then sliced and steamed at any stage of growth. Wear gloves to handle the pads or prickly pears and use tongs while singeing or brushing to remove the prickles. Although small and innocent looking, glochids (prickly bristles) can penetrate the skin and cause considerable pain.

Propagation

Pieces of the stem of any size can be detached and laid aside for a few hours to allow a protective "skin" to form over the cut. They can then be planted in pots of sand or very sandy soil. Place them in a spot where they'll receive full sun and do not water until the soil becomes pretty dry. After a while the soil can be moistened regularly but never kept constantly saturated. In mild climates, cuttings will root if planted directly in soil outside. Seeds can be sown in the spring or summer in well-drained pots of sandy soil that are half-filled with crocks that are covered with rough siftings from the compost. Make sure the surface is smooth and even and sow the seeds thinly on top. Cover them with a bit of fine soil. Moisten and lay a piece of glass across the top. The pots should be set in a warm greenhouse or sunny window until they start to sprout after which the glass should be removed so they can receive full light and air. It isn't good to keep the glass over the seedlings, so if some of them are up before others, they may be pricked out and placed in another pot. The transplanted seedlings should not be disturbed until they are well rooted after which they can be planted separately in small pots.

O. polyacantha

VARIETIES

• O. compressa;
• O. arenaria;
• O. fragilis;
• O. imbricata;
• O. phaeacantha;
• O. polyacantha;
• O. fulgida & var. fulgida;
• O. invicta;
• O. lindheimeri;
• O. microdasys & var. alba, monstrosus;
• O. tunicata;
• O. vestita;
• O. aurantiaca;
• O. basilaris;
• O. cylindrica;
• O. dillenii;
• O. ficus-indica;
• O. leucotricha;
• O. pentlandii (boliviana);
• O. pottsii (filipendula);
• O. spinosissima;
• O. whipplei;
• O. neoargentina (Tree Opuntia);
• O. paraguayensis (Riverina Pear).