Tills dark green, desert type, columnar cactus, known as Peruvian apple cactus, comes from Brazil to Argentina. It has 5—9 thick ribs and few branches. The ribs are rounded, with 8—9 stout yellow or reddish- brown spines growing from brown areoles. Nocturnal, funnel-shaped white flowers are produced in summer, which are up to 6 in. (15 cm) long. Outer petals may be tipped green-brown or red.

Size: Height up to 15 ft. (5 m).

Light: Direct sunlight.

Temperature: Normal room; winter minimum 50°F (10°C).

Moisture: Keep moist (but never wet) from spring to fall; in winter apply only enough water to prevent the soil drying out.

Feeding: Use half-strength liquid tomato fertilizer once a month in spring and summer.

Propagation: Sow seed in spring; take cuttings of young branches in late spring or early summer.

Special needs: Give the plant as much direct sun as possible throughout the year to encourage flowering.

The parodias are mainly small, globe shaped or elongated desert-type cacti, with colorful or intricately decorative spines bearing crowns of brightly colored flowers. P. chrysacanthion from Argentina is covered in spirally arranged tubercles, each topped with an areole bearing 30—40 straight, pale-yellow spines, ½ in. (1 cm) long, and 3—5 golden-yellow spines, up to 1 in. (2.5 cm) long.

The very apex of the plant is wooly and tufted with erect spines. The yellow flowers appear in spring and are up to 1 in. (2.5 cm) across. P. nivosa is a globe- shaped desert cactus from Brazil, grown for its attractive spines and its display of bright red flowers. It has many low ribs, set with areoles bearing hair like spines.

The apex of the plant has a white, wooly crown and bears funnel-shaped flowers, 2 in. (5 cm) long arid across, which appear around this indentation, each lasting for several days. P. crassigibba (for­merly Notocactus crassigibbus) is a flattened dome-shaped plant of up to 7 in. (17 cm) in diameter.

It is shiny dark green, with 10-16 low, rounded ribs dotted with chin like tubercles. The 1 in. (2.5 cm) long spines are off- white to gray or light brown in color. White, yellow, or red-purple flowers are produced in spring and summer.

Size: Height to 6 in. (15 cm), spread 4 in. (10 cm).

Light: Direct sunlight.

Temperature: Normal room; winter minimum 50°F (10°C).

Moisture: Keep the soil moist (but never wet) from spring to fall. In win­ter, apply only enough water to pre­vent the soil drying out.

Feeding: Give liquid tomato fertilizer once a month in spring and summer.

Propagation: Remove offsets during summer. Allow to dry for up to three days, then pot into cactus soil mix. If no offsets form, raise from seed.

Special needs: Give the plant as much direct sun as possible all year to help it to keep a good shape and encourage flowering. If the roots show signs of rotting when the plant is being repotted, cut damaged tissue back to healthy growth, then repot.

This small, but quick-growing, genus of desert cacti from Argentina easily produces offsets from the base, and flowers while still young. The indi­vidual stems are globe-shaped and are covered in tubercles arranged in ridges with bristly, thin, white spines, ¹/₈ in. (2—3 mm) long, in clusters of around 20.

Pale red flowers appear in late spring around the base of the stems, giving the plant its common name, red crown cactus. They are borne over several weeks and each lasts 2—3 days. R. chrysacantha is similar to R. krainziana, which has spines in a spiral, and R. miniscula, which has shorter brown spines and masses of flowers.

Size: Spread 6 in. (15 cm) in about four years.

Light: Direct sunlight, except at noon in summer.

Temperature: Normal room; winter minimum 40°F (5°C).

Moisture: Keep the soil moist (but never wet) from spring to fall. In win­ter, apply only enough water to pre­vent the soil drying out.

Feeding: Give liquid tomato fertilizer once a month in spring and summer.

Propagation: Offsets can be cut or gently pulled off to ensure the con­tinuation of a particular plant, but rebutias grow readily from seed, often flowering at the end of their first growing season and giving a wide range of flower colors.

Special needs: This plant can literally flower itself to death within 5—6 years, so it is wise to propagate a par­ticular favorite from offsets before this happens.

There are over 200 named cultivars of the rain-forest type Christmas cactus, all of which flower during winter. They have flowers in shades of pur­ple, pink, white, red, orange, or yel­low. The arching stems consist of oblong, flattened segments, the edges of which are scalloped or toothed, with tiny areoles set in the notches along the edges and at the ends of each segment.

The tip areoles are slightly elongated and it is from these that the flowers develop, singly or in pairs. Christmas cactus is of garden origin, although its parents are natives of Brazil. S. truncata (syn. Zygocactus truncata), the crab or lobster cactus, bears deep pink, red, orange, or white flowers during fall and winter.

Size: Spread 12—18 in. (50—45 cm) across in 10 years.

Light: Indirect sunlight.

Temperature: Normal room.

Moisture: Apart from a 3—4 week rest period after flowering (when the soil should only be given enough water to prevent it drying out) keep the soil moist at all times.

Feeding: Apply standard liquid tomato fertilizer every two weeks, from the appearance of flower buds until the last bud has opened. Stop feeding during the rest period, then apply standard liquid fertilizer once a month during the rest of the year.

Propagation: Carefully break at least two segments from the parent plant. Push into a small pot of potting soil, deep enough so that the cutting can stand upright. Water gently. Several cuttings can be inserted into a larger pot for an immediate effect.

Special needs: The buds are likely to drop off if the plant is moved, sub­jected to a sudden change in temper­ature, or over- or under watered once they have started to form. During summer, it may be placed in a shady spot outdoors, but it must be back inside before there is a risk of frost.

In its natural desert habitat in south­west USA and northeast Mexico, Echinocactus, also known as barrel cactus, can live for over 100 years, eventually forming a mound about 6½ ft. (2 m) across. Its shape is like a slightly flattened ball. E. grusonii, the golden barrel cactus, has a green stem of 50 ribs and buff-colored spines. The wider crown stems bear straw- colored flowers in summer.

Size: Height 5—8 in. (12—20 cm), spread 1 ft. (50 cm).

Light: Direct sunlight.

Temperature: Normal warm room temperature from spring to fall. During the winter rest period 50°F (10°C). No lower than 40°F (5°C).

Moisture: Keep soil moist from spring to fall, in winter apply just enough water to prevent it drying out.

Feeding: Use standard liquid tomato fertilizer once a month in spring and summer.

Propagation: Sow seed.

Special needs: Pot or repot in spring.

This desert type is the largest genus of the cactus family, comprising over 300 species. It is different from other cacti in that the species do not have ribs and have spirally arranged tuber­cles, each with an areole at the tip bearing clusters of spines.

M. zeil­manniana, or rose pincushion, from central Mexico, has clusters of four red-brown main spines surrounded by 15—18 bristly, white radial spines. Initially a solitary plant, it grows to form a cluster of glossy green, globe- shaped stems. The violet-pink or pur­ple flowers are produced in spring in a ring around the top of the plant.

Size: Spread 4 in. (10 cm) in four years.

Light: Direct sunlight.

Temperature: Normal warm room from spring to fall. During winter rest period 50°F (10°C). No lower than 40°F (5°C).

Moisture: Keep moist from spring to fall; in winter apply enough water to prevent the soil drying out.

Feeding: Use liquid tomato fertilizer once a month in spring and summer.

Propagation: Sow seed – allow the pulp from the berries to dry, then pick out the seeds — or take offsets by cut­ting or pulling them away from the parent plant, drying them for 24 hours, then planting.

Special needs: Flowers are produced from part of the stem which grew last year, so a poor growth season means less chance of a good display of flow­ers the following spring.

The flowers of this rain-forest species, known as Easter cactus, are intense red, and are produced either singly or in groups of 2-5, from a cluster of long, brown bristles at the end of new stem segments, over a period of several weeks in spring. Each individual flower may only last two or three days.

The segments are thin, flattened, and up to 1 ¼ in. (5 cm) long, forming stems that are upright at first, drooping down as they get longer. This plant comes from eastern Brazil. It is ideal for a hanging basket.

Size: Spread 12—16 in. (30—40 cm).

Light: Indirect sunlight.

Temperature: Normal room.

Moisture: Keep moist at all times, apart from a 3—4 week rest period after flowering when the soil should only be given enough water to pre­vent it drying out.

Feeding: Use standard liquid tomato fertilizer every two weeks in spring, from the appearance of the flower buds until the last bud has opened. Stop feeding luring the rest period, then apply standard liquid fertilizer once a month for the rest of the year.

Propagation: Take at least two seg­ments by breaking them carefully from the parent plant. Push deeply enough into a small pot of soil mix to stand upright, then water gently to settle the soil. Several cuttings can be inserted into a larger pot for an immediate effect.

Special needs: Repot after the rest period in spring.

This desert type, Mexican Opuntia, takes its common name, prickly pear, from its spiny, pear-shaped fruit, and naturally forms shrubby thickets 16—24 in. (40—60 cm) in height. Indoors, however, it tends to remain much more compact. It does not have ridges, but velvety-looking stem segments, reaching 2½—6 in. (6—15 cm) long.

These are covered by areoles packed with tiny golden or white, hooked bristles (glochids). It is grown for its shape and appearance, rather than its yellow flowers, which may not appear on indoor specimens. O. brasiliensis, from South America ultimately becomes treelike in the wild, growing to 30 ft. (9 m) or more, but it is unlikely to achieve this in the home.

It has a cylindrical trunk, which branches as it grows to produce flattened, oval, leaf like segments and pale yellow flowers.

Size: Height and spread 1 ft. (30 cm) in 10 years.

Light: Direct sunlight.

Temperature: Normal room; winter minimum 50°F (10°C).

Moisture: Keep soil moist (but never wet) from spring to fall. In winter apply only enough water to stop the soil drying out.

Feeding: Apply tomato fertilizer every two weeks in spring and summer.

Propagation: Detach segments by cutting or pulling from the parent plant in spring or summer, allow to dry for up to three days, then plant into small pots of cactus soil mix.

Special needs: The glochids are easily detached, even by the most gentle touch, and quickly penetrate the skin. They are highly irritant if left and should be removed as quickly as possible using adhesive tape.

The cactus family have adapted to the con­ditions in which they grow by reducing their surface area to a moisture-conserving minimum. They are all succulents in that they store moisture within the main part of the plant itself, but the two types of cactus — desert and rain forest — have differing adaptations.

To cope with hot weather and long periods of drought, desert- type cacti have a waxy outer covering (cuticle) and ridges on their stems, and their leaves have become spines or hairs. These spines grow from cushion­ shaped, modified side shoots (areoles), sometimes on wart-like swellings (tubercles). The areoles are the points at which flowers and offsets arise.

Rain-forest cacti establish in places where debris has accumulated, such as on tree branches. Despite the generally humid rain forest atmosphere, these pockets dry out quickly, so moisture needs to be stored within the plant. They do not grow in the upright, cylindrical shape common to many desert cacti, but tend to have long, trailing, modified stems consisting of numerous, leaf like segments.