Arrojadoa DINAE

Arrojadoa DINAE - Dina's arrojadoa, Arrojadoa dinae, Arrojadoa MULTIFLORA.

Arrojadoa is a small genus of cacti in the cactus family (Cactaceae), comprising about five species. All of them are endemic to Brazil and grow in arid regions of the states of Bahia, Minas Gerais, and Piauí, on rocky soils among dry scrub.

The plants form shrubby clusters of slender cylindrical stems branching from the base. In various species, stems can be up to 7 cm (2.8 in) thick or noticeably thinner, reaching 180 cm (5.9 ft) in height. The ribs are low, almost entirely hidden beneath densely situated spines. In some species, including this one, underground tubers develop.

Flowers appear at the very summit of the stem in a pseudocephalium - a tuft of white wool and bristles. They are tubular, 3-4.5 cm (1.2-1.8 in) long, pink, red, purple, yellow, or white, opening during the day and lasting only one to two days, after which they turn black and drop. Birds pollinate them. The fruit is a small juicy berry of pink, violet, or red color.

Arrojadoa dinae is a species native to the Brazilian states of Minas Gerais and Bahia. Its main feature is underground tubers: aboveground stems completely dry up in winter, and in spring sprout anew from the tuber preserved in the soil.

The first pseudocephalium forms when the stem reaches about 20 cm (7.9 in) in length. The flowers are bicolored, brownish-carmine on the outside and yellowish inside. Cross-pollination of flowers from different plants is usually required for fruit set, but in this species fruits occasionally form upon self-pollination as well.

Arrojadoa seeds are small, black, shiny, ripening in juicy berry-like fruits. Usually they germinate well without any presowing treatment; scarification and stratification are not required. As a precaution before sowing, the substrate is drenched with a weak solution of potassium permanganate or biofungicide.

Consistently high germination is achieved by soaking seeds for 24 hours in a solution of gibberellic acid GA3 at a concentration of 1000 ppm, which is 1 g per 1 L of water. After such soaking, seeds are sown while still moist, not allowing them to dry out.

For sowing, a permeable mix is prepared, such as 2 parts sand and 1 part leaf soil, which is pre-sterilized. The top layer is best made of pure sand - on it, both the black seeds themselves and the sprouts will be clearly visible. Generous drainage is arranged at the bottom of the seed tray.

Seeds are spread over the surface of moistened substrate and not covered with anything, only lightly pressed in so they do not dry out. The sowing is moistened with a spray bottle using a growth stimulant solution: SUPERthrive, HB-101, Aminozol, Epin, or Zircon. The container is covered with glass or film or placed in a propagator and kept in partial shade at a temperature of 22-25 °C (72-77 °F), with slightly cooler conditions permissible at night.

Initial sprouts appear in just a few days; main germination is usually completed within one and a half to two weeks, while individual seeds may delay longer. Seedlings are very prone to rot, so sowings are ventilated regularly immediately after sprout emergence, and the top layer of substrate is allowed to dry out briefly.

After several weeks, the cover is removed entirely, gradually acclimating seedlings to dry air and direct sun. At first they are regularly watered and misted, lengthening intervals between waterings each time. Many collectors, to avoid problems, grow seedlings on rootstocks and then root or regraft them.

Special notes: Seed viability decreases only slightly after several years of dry storage.

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Arrojadoa is grown in a sunny spot with bright illumination.

Overwintering is kept dry, at a temperature of 12-15 °C (54-59 °F), with 8 °C (46 °F) being the minimum permissible. Good room ventilation is mandatory year-round.

Watering during the growth period is moderate. High moisture of the substrate and air inevitably leads to rotting, which is especially hazardous for species with tuberous roots, such as this one.

The substrate must be well-drained, such as a mixture of leaf mold and sod soil, coarse sand, and gravel or other grit in a 2:2:2:1 ratio, with acidity around pH 5.6. A generous drainage layer is placed at the bottom of the pot. Clustering species grow rapidly and require more frequent repotting.

Feeding is carried out only during active growth with a low-nitrogen cactus fertilizer. Fertilizers are not applied during dormancy.

On its own roots, arrojadoa is quite finicky, which is why many specialists recommend keeping it grafted. Harrisia (Harrisia jusbertii), Peruvian apple cactus (Cereus peruvianus), or trichocereus (Trichocereus spachianus) are used as rootstocks. Grafted plants slightly lose their typical habit, but easily tolerate excess watering and high air humidity.