Aporocactus, Ariocarpus and Astrophytum Cacti

Aporocactus

From the Greek aporos, impenetrable, but for no obvious reason (Cactaceae). Greenhouse plants with drooping, spine-covered stems up to 2 feet long. A. flagelliformis is the well-known ‘rat-tailed cactus’, suitable for window culture and hanging baskets.

Species cultivated

A. flagelliformis, rat-tailed cactus, slender stems with fine spines, cerise-pink flowers in spring, Peru. A. martianus, stems erect or sprawling, flowers red to scarlet with violet edge, Mexico. A. x mallisonii, hybrid between A. flagelliformis and Heliocereus speciosus, large bright red flowers.

Cultivation

A suitable growing medium is an average potting compost to which should be added a fifth part of sharp, coarse sand with broken brick included. Repot every two or three years, give light stimulants when in bud; give plenty of light at all times and sun whenever possible. These plants can take more water than many cacti but soil must be well drained. Temperature minimum 40 °F (4°C) in winter when plants must be kept dry, 70 °F (21°C) in summer. Propagation is by seeds sown in sandy soil in spring; cover them by their own depth only and keep them moist and warm. Cuttings of young shoots may also be used for propagation, dry these before placing them on sharp sand and peat in equal quantities; do not push cuttings into this or they may rot; aerial roots often form on the stems.

Ariocarpus

From aria, the name for the whitebeam, and the Greek carpos, a fruit, referring to the shape of the fruits (Cactaceae). Greenhouse cacti mainly Mexican in origin. Plants have a stout root stock, rather flat stems with no spines, the areoles are borne on tubercles. Plants have a rock-like appearance.

Species cultivated

A. fissuratus, very rock-like, tubercles greyish and flattened, flowers pink with a darker mid-rib. south-west Texas and Mexico. A. retusus, flattish growth, grey tubercles flowers pale pink. Mexico. A. trigonus, tubercles more erect than other species, the yellowish flowers appear from the woolly top of the plant, Mexico. A. kotchubeyanus, dark green tubercles with a woolly furrow, flowers pink to carmine-red, Central Mexico.

Cultivation

The compost should be very porous; regular compost, with a j part of added coarse sand and broken brick is suitable. Plants should be given a very sunny place in the greenhouse. Repot every four years as plants are very slow growing. Water sparingly from April to September, then give no water at all in winter. Maintain a temperature from March to September, of 70-75 °F (21-24°C); plants can stand a minimum of 40 °F (4°C) in winter.

Propagation is by seeds sown in spring in deep pans of a good seed compost.

Keep moist and at a temperature of 70°F (21°C) during germination. Seedlings grow very slowly; maintain warmth but give no direct sun for the first year.

Astrophytum

From the Greek aster, star, phytos. plant, referring to the shape of the plant (Cactaceae). Star cactus. Formerly included in Echinocactus, these cacti mostly have globular stems, some deeply ridged with from four to eight ribs. Flowers are produced from areoles at the top of the plant. A well-grown specimen produces flowers at each areole as formed. There are four species and many cultivars produced through crossing.

Species cultivated

A. asterias, round and almost ribless, flowers yellow, large, with red centre. A. capricorne, ribbed with strong, curved spines, flowers yellow. A. myriostigma, bishop’s cap, spineless. flowers yellow. A. ornatum, many curling spines, flowers lemon-yellow. All these are natives of Mexico. Cultivation

Astrophytums should be given a very porous soil with added lime A suitable compost consists of 2 parts of loam, 1 part of peat and 1 part of sharp, coarse sand. Add 1 ounce of ground chalk and 1/4 pound of reliable base fertilizer to each bushel. Repot only every four years except seedlings which may be repotted every year. Water from April to September, after which the soil is kept quite dry; never allow soil to remain wet for long periods or the plant will rot. Give as much sun as possible at all times; there is no limit to warmth these plants can stand in summer. The temperature in winter should not fall below 40 °F (4°C) As these plants never produce off-sets normally they must be grown from seed. The seeds are large with a hollow side like a cowrie shell. Sow them in a good seed compost, just pressing the seed in. They may germinate in 48 hours at a temperature of 70 °F (21°C). Prick out when the cotyledon (seed-leaf) has been absorbed.

10. July 2017 by Dave Pinkney
Categories: Cacti and Succulents | Tags: , , , , , | Comments Off on Aporocactus, Ariocarpus and Astrophytum Cacti

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