Growth habit: Cylindrical shaped, solitary stem
Mature Size: 10 in. tall, 8 in. wide
Special features: Oversized flower, squatty stem
Echinocereus rigidissimus requires porous soil as it is sensitive to overwatering. It prefers a soil with plenty of stones with little organic material to ensure that it dries as quickly as possible. Echinocereus rigidissimus requires full sun to part shade during its active growing season from spring through to early autumn, as well as adequate air circulation to reduce the chance of rotting.
The natural habitat of Echinocereus rigidissimus is distributed abundantly throughout Chihuahua and Sonora in Mexico, as well as in the United States in Arizona. It grows at elevation from 1200 to 2000 metres above sea level. This cactus prefers south facing slopes and is rarely seen on flat ground. It prefers the 1500 meter elevation. Plants are resistant to small grass fires, but cannot tolerate hotter fires. With perfect habitat, these plants have been seen growing up to 45 centimeters in height. A 2018 measurement of one plant in the Santa Catalina mountains showed a record height of 48 centimeters.
Flowering occurs from late April to early June depending on the elevation and spring heat. These plants will not flower when stressed, but lack of flowering is rare. Their habitat has been negatively affected by cattle, cactus collectors and off road vehicles. These plants are becoming less common in southern Arizona.
The flowers of the rainbow hedgehog cactus produce trumpet-shaped blooms in shades of bright pink at the top of the cactus during the late spring and summer months. They are usually about 2–3 inches in diameter and attract pollinators such as bees and butterflies.
Growth habit: Columnar
Mature Size: Up to 20 ft. tall
Special features: Easy to maintain
Echinopsis pachanoi is native to Ecuador, Peru and Colombia. Its stems are light to dark green, sometimes glaucous, with a diameter of 6–15 cm (2.4–5.9 in) and usually 6–8 ribs. The whitish areoles may produce up to seven yellow to brown spines, each up to 2 cm (0.8 in) long although typically shorter in cultivated varieties, sometimes being mostly spineless. It is normally 3–6 m (10–20 ft) tall and has multiple branches, usually extending from the base but will emerge around broken branches. The tallest recorded specimen was 12.2 metres (40 ft) tall.
It thrives in hardiness zones 8b to 10. The range of minimum temperatures in which it is known to grow is between -9.4 °C and 10 °C. Because it grows naturally in the Andes at high altitude and with high rainfall, it can withstand temperatures far below that of many other cacti. It requires fertile, free-draining soil.
When the San Pedro cactus flowers bloom, they emit a sweet fragrance that attracts pollinators like bees and butterflies. The flowers are usually large and trumpet-shaped and come in various colors, including white, cream, and yellow. The petals have a delicate texture and often have a waxy appearance. The fragrant flowers usually open during the day and close at night. They have a short blooming period, typically lasting for a day or two.
In winter, plants will etiolate, or become thin, due to lower levels of light. This may be problematic if the etiolated zone is not sufficiently strong to support future growth as the cactus may break in strong winds.
Growth habit: Columnar
Mature Size: 12 ft. tall, 4 ft. wide
Special features: Easy to grow
Pilosocereus azureus is a blue cactus native to the semi-tropical areas of Brazil. The blue gets bluer as the cactus ages. It is a tall pillar type cactus with downy fur along the ribs and beautiful golden spines. At night, it blooms white flowers that are pollinated by bats and sphinx moths.
It grows quickly, up to 12’, but will stay windowsill size for several years. It needs full sun and almost no water. The brighter the sunlight, the bluer it gets.
It thrives in hardiness zones 9b-11b. The blue-green color of the Pilosocereus azureus Brazilian blue cactus is due to a waxy coating on the stem that helps to protect it from the sun. Its stem is no ordinary stem either; it’s adorned with ridges and covered in areoles along the edges. As this remarkable plant matures, those golden spines turn white and create a striking contrast against its vibrant hues.
Growth habit: Columnar
Mature Size: 60 ft. tall
Special features: Up to 200 years long lifespan
The saguaro is a columnar cactus that grows notable branches, usually referred to as arms. Over 50 arms may grow on one plant, with one specimen having 78 arms. Saguaros grow from 3–16 m (10–52 ft) tall, and up to 75 cm (30 in) in diameter. They are slow growing, and routinely live 150 to 200 years. They are the largest cactus in the United States.
Saguaros have a relatively long lifespan, often exceeding 150 years. They may grow their first side arm around 75–100 years of age, but some never grow any arms. Arms are developed to increase the plant’s reproductive capacity, as more apices lead to more flowers and fruit. A saguaro can absorb and store considerable amounts of rainwater, visibly expanding in the process, while slowly using the stored water as needed. This characteristic enables the saguaro to survive during periods of drought. It is a keystone species, and provides food and habitat to a large number of species.
Saguaros have been a source of food and shelter for humans for thousands of years. Their sweet red fleshed fruits are turned into syrup by native peoples, such as the Tohono Oʼodham and Pima. Their ribs are used as building materials in the wood-poor deserts. The saguaro cactus is a common image in Mexican and Arizonan culture, and American Southwest films.
Growth habit: Columnar
Mature Size: Up to 3-4 feet
Special features: Has thorns, spines, prickles, teeth
Bergerocactus emoryi is a relatively small cactus, but it can form dense thickets or colonies, with the dense yellow spines giving off a velvety appearance when backlit by the sun. From April to May, yellow, green-tinged flowers emerge, which transform into reddish, globular fruit. This species is native to the California Floristic Province, and is found in northwestern Baja California and a small part of California, in San Diego County and on the southern Channel Islands. Where the Mediterranean climate of the California Floristic Province collides with the subtropical Sonoran Desert near El Rosario, hybrids with two other species of cacti are found.
This species is a shrub-like cactus, forming thickets of columnar to prostrate stems. The colonies have a velvety appearance when backlit by the sun. The stems are usually less than 2 metres (6.6 ft) long, covered in numerous, interlaced, yellow and needle-like spines. The stems are 3–6 cm (1.2–2.4 in) in diameter, cylindrical, and with 12 to 18 ribs. There are 30 to 45 spines per areole, and most are less than 2 mm (0.079 in) in diameter. There are 1 to 3 central spines, which are curved downward, the longest less than 6 cm (2.4 in). The radial spines are straight.
The flowers emerge either laterally or at the apex of the stem, at the distal margin of the spine cluster. The flower is 3.5–5 cm (1.4–2.0 in) long, and 2.5–4 cm (0.98–1.57 in) in diameter. After blooming, a reddish, globular fruit emerges, covered in dense spines, and extruding seeds and pulp at the tip. The seeds are 3 mm (0.12 in) large, shiny and black.
Growth habit: Trailing, hanging
Mature Size: 5 ft. long
Special features: Easy to grow
Aporocactus used to be a subgenus in Disocactus, but according to molecular evidence, it should be excluded from Disocactus and form a genus on its own.
Rattail cacti are very easy to grow, being suitable for a greenhouse and container, indoors or out. These plants need a minimum temperature of 6 °C (43 °F). They should be grown in bright, indirect light, in a fairly rich potting mix. The best compost consists of four parts sandy loam, and one part of equal quantities of sand and crushed brick. They should be repotted every other year because their soil tends to sour. This does not mean, however, that they will need larger pots. Once the plants are established, the compost should be kept moist from April to October; less water is required from November until March, just enough to keep the stems from dying back. In the winter, old or discolored stems may be cut out at the base to encourage new growth.
The Latin specific epithet flagelliformis means “shaped like a whip”, in reference to the long shoots. The common name “rattail” refers to the same feature.
The rat tail cactus flowers are tubular in shape and can vary in color, ranging from shades of pink, violet-red, or purple. The blooms typically appear in late spring or early summer and last for several weeks.
Growth habit: Cylindrical
Mature Size: 1224 in.
Special features: Usually solitary
Some species of barrel cactus reach over 1 metre (3.3 ft) in height at maturity, and have been known to reach 3 metres (9.8 ft) in some regions. The ribs are numerous and pronounced, and the spines are long and can range in color from yellow to tan to red, depending on the age of the plant and the species. Flowers appear at the top of the plant only after many years. The barrel cactus can live to be over 100 years old.
Blue Barrel cactus buds typically start to bloom in April with a bright yellow or orange flower. Pink and red varieties also exist but occur less frequently. The flowers only appear on the very top of the plant. As the flowers begin to wilt in early May, they may change color. A late summer desert rainstorm can produce a late bloom, as shown in the photograph below of the orange-flowered variety (it bloomed two days after a hurricane in mid-August and continued to bloom through the end of September).
As the flowers wilt away, small pineapple-shaped greenish fruit may form. Left untouched, the fruit has been known to last a full calendar year. The fruit can be easily removed but is not usually consumed because it is fairly dry and bitter.
Growth habit: Columnar, Spiral
Mature Size: Up to 16 ft. tall, 5 in. wide
Special features: Night blooming cactus
It is endemic to the Argentine provinces of Catamarca, Chaco, Córdoba, Formosa, Jujuy, La Rioja, Salta, Santa Fe, Santiago del Estero and Tucumán, and north of the city of San Luís. In Bolivia, it is found in the departments of Chuquisaca, Santa Cruz and Tarija. It grows atop arid, windswept hills, within sparse forests, wooded plains, and also on the edges of salt flats, often an elevation of 500–2,000 m (1,600–6,600 ft).[3] Like similarly related cacti, C. forbesii has adapted to extreme temperature fluctuations, including full-sun conditions during the daytime with seasonal near-freezing temperatures at night (especially in winter). Plants growing over 2,000 m above sea level may even contend with wintertime snowfall.
The cylindrical, glaucoma shoots are initially blue-green and later turn light green, with a diameter of 5 to 8 centimeters. The columns are composed of 4-8 blunt, compressed ribs. The gray areoles are small. The (mostly singular) central spine, which occasionally forms two or three, is strong, yellowish-brown and up to 16 centimetres (6.3 inches) long. The five surrounding radial spines reach a length of up to 2 centimetres (0.79 inches).
The waxy blooms open up only at night but linger no longer than 24 hours, giving them the nickname “Night blooming cereus.” They have pinkish-white to red-colored petals.