Origin and Habitat: East of Mato Verde, Minas Gerais, Brazil.
Altitude range: 1067 metres.

• Arrojadoa eriocaulis var. rosenbergeriana Van Heek & W.Strecker
• Arrojadoa rosenbergeriana (Van Heek & W.Strecker) P.J.Braun, Esteves & Van Heek

• Arrojadoa dinae Buining & Bredero
• Arrojadoa beateae P.J.Braun & Esteves

• Arrojadoa dinae subs. eriocaulis (Buining & Bredero) N.P.Taylor & Zappi
• Arrojadoa eriocaulis Buining & Bredero
• Arrojadoa dinae var. nana P.J.Braun & Esteves
• Arrojadoa dinae subs. nana (P.J.Braun & Esteves) P.J.Braun & Esteves
• Arrojadoa eriocaulis var. albicoronata Van Heek, R.J.Paul, Heimen, Hovens & W.Strecker
• Arrojadoa albicoronata (Van Heek, R.J.Paul, Heimen, Hovens & W.Strecker) P.J.Braun & Esteves
• Arrojadoa eriocaulis subs. albicoronata (Van Heek) P.J.Braun & Esteves
• Arrojadoa eriocaulis var. rosenbergeriana Van Heek & W.Strecker
• Arrojadoa rosenbergeriana (Van Heek & W.Strecker) P.J.Braun, Esteves & Van Heek
• Arrojadoa multiflora F.Ritter

Description: Arrojadoa eriocaulisSN|4829]]SN|4830]] var. rosenbergeriana (ayn: Arrojadoa rosenbergerianaSN|4829]]SN|4859]]), is generally included within (as a synonym of) Arrojadoa dinae subs. eriocaulisSN|4859]]SN|4829]], suggesting that there is not really a fundamental difference between the two, and hard to name accurately without knowing where they come from. In particular the var. rosenbergeriana distinguish for the darker and stronger spines. However the distinguishing characteristics of var. rosenbergeriana, appear to fall within the natural variation of Arrojadoa dinae subs. eriocaulisSN|4830]]SN|4829]] and it should be synonymized with the latter, but it still has a value for a collector because they identify plants with particular characters.

Cultivation and Propagation: This species is not particularly difficult on own roots providing it is given a little extra heat during the winter, but this and all its relatives do best when grafted. Arrojadoas bloom on the forest floor all year-round and are accustomed to receiving lots of summer rain and winter dew, so they never dry out for long in the wild. They most definitely are not desert plants and don't survive if treated as such. In arid climates they fare best in containers, where the roots remain moist longer.
Growth rate: It is a relatively rapidly growing and easily flowering species that will make clumps given the best conditions.
Soils: It likes very porous standard cactus mix soil and can also be grown in orchid bark, or on cork sheets or a tree branch like for epiphytes.
Repotting: Use pot with good drainage.
Watering: It should be watered generously during the growing season, keep drier in winter. Water them less than average if in bigger pots.
Fertilization: Feed with a high potassium fertilizer in summer.
Hardiness: Reputedly sensitive to frost (in his biotope the temperature never drops below 15 ° C), but less so if kept on the dry side prior to, and during, cold weather. However warmth throughout the year will increase the grower's success (not less than 8-12°C during rest season).
Exposition: Outside bright, hot conditions or afternoon shade, inside it needs bright light, and some direct sun. Strong light encourages flowering and heavy wool and spine production.
Uses: It is an excellent plant for container growing. It always looks good and stays small.
Pests & diseases: It may be attractive to a variety of insects, but plants in good condition should be nearly pest-free, particularly if they are grown in a mineral potting-mix, with good exposure and ventilation. Nonetheless, there are several pests to watch for:
- Red spiders: Red spiders may be effectively rubbed up by watering the plants from above.
- Mealy bugs: Mealy bugs occasionally develop aerial into the new growth among the wool with disfiguring results, but the worst types develop underground on the roots and are invisible except by their effects.
- Scales: Scales are rarely a problem.
- Rot: Rot is only a minor problem with cacti if the plants are watered and “aired” correctly. If they are not, fungicides won't help all that much.
Propagation: The Arrojadoas are quite easy to grow from cuttings, seed or (often) graft. Seeds germinate in 7-14 days at 21-27° C in spring, remove the glass cover gradually as the plants develops and keep ventilated, no full sun for young plants! To make a cutting twist off a branch and permit it to dry out a couple of weeks, lay it on the soil and insert the stem end partially into the soil. Try to keep the cutting upright so that the roots are able to grow downward.