Origin and Habitat: Frailea perumbilicata has a relatively small range in Rio Grande do Sul (Brazil) and Concepción departments in Uruguay.
Altitude: 150-500 metres above sea level.
Habitat: In Brazil it grows on grass plains, elsewhere mostly on rocky outcrops and stony fields. Frailea perumbilicataSN|3675]]SN|3675]] is not abundant and its distribution is sparse. In general, Frailea species have a relatively short lifespan but rapid reproduction (generation length is 3-5 years). The major threats are trampling by grazing cattle, agriculture, forestry (Eucalyptus plantations), and fire.

• Frailea perumbilicata F.Ritter
• Astrophytum perumbilicatum (F.Ritter) Halda & Malina
• Frailea castanea var. perumbilicata (F.Ritter) Prestlé

• Frailea schilinzkyana (F.Haage ex K.Schum.) Britton & Rose
• Astrophytum schilinzkyanum (F.Haage ex K.Schum.) Halda & Malina
• Cactus schilinzkyanus (F.Haage) Kuntze
• Echinocactus schilinzkyanus F.Haage ex K.Schum.
• Frailea concepcionensis Buining & G.Moser
• Frailea schilinzkyana subs. concepcionensis (Buining & G.Moser) P.J.Braun & Esteves
• Frailea friedrichii Buining & Moser
• Astrophytum friedrichii (Buining & Moser) Halda & Malina
• Frailea grahliana (F.Haage) Britton & Rose
• Astrophytum grahlianum var. ( F.Haage ex K.Schum.) Halda & Malina
• Cactus grahlianus (F.Haage) Kuntze
• Echinocactus grahlianus F.Haage ex K.Schum.
• Frailea grahliana subs. concepcionensis Prestlé
• Frailea grahliana subs. moseriana (Buining & Bredero) Prestlé
• Frailea moseriana Buining & Bredero
• Frailea moserianum (Buining & Bredero) Halda & Malina
• Frailea ignacionensis Buining & G.Moser
• Astrophytum ignacionense (Buining & Moser) Halda & Malina
• Frailea klingleriana Prestlé
• Frailea perumbilicata F.Ritter
• Astrophytum perumbilicatum (F.Ritter) Halda & Malina
• Frailea castanea var. perumbilicata (F.Ritter) Prestlé
• Frailea schilinzkyana f. cristata hort.
• Frailea ybatensis Buining & Moser
• Frailea grahliana subs. ybatensis (Buining & G.Moser) Prestlé
• Frailea ybatense Buining & Moser

Description: Frailea perumbilicataSN|3675]]SN|3675]] is a tiny solitary cactus with globular stems typically flattened and umbilicate above, (wider than taller). Frailea perumbilicataSN|3634]]SN|3675]] is considered by many a synonym of Frailea schilinzkyanaSN|3675]]SN|3634]]. This two taxa are linked one to each other by plants with intermediate characteristics and shows similar features, namely size and form of stems, radial spines, flowers, fruit, etc., prove, that is impossible to differentiate between these taxa.
Habit: Frailea perumbilicataSN|3675]]SN|3675]] is a very small cactus that remains solitary or (occasiaonally) somewhat cespitose.
Stem: It is diminutive in size, 2-3 cm high and in diameter, depressed globular and somewhat flattened and umbilicate above, (wider than taller). Dull yellowish-green, green or olive green.
Ribs: Usually 15, divided into rounded tubercles.
Areoles: Placed on the upper side of the tubercles.
Radial spines: About 6 to 10 needle-like, twisted, spreading, more or less appressed and reflexed 2-3 mm long tannish-brow in colour.
Central spines: Usually absent, occasionally one stouter than the radials.
Roots: Fat central tap root.
Flowers: Sulphur yellow, infundibuliform, 3,4-4 cm long, often cleistogamous (Even when their flowers do not open, they still form fruits with many seeds)
Blooming season: Flowers will open only in great heat, in the hottest, brightest, afternoon sun, if at all.
Fruits: Dry, indehiscent, that detach easily, yellowish, pericarp membranous, fragile that break easily, releasing the seed.

Bibliography: Major references and further lectures
1) James Cullen, Sabina G. Knees, H. Suzanne Cubey “The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass” Cambridge University Press, 11/Aug./2011
2) David Hunt, Nigel Taylor “The New Cactus Lexicon” DH Books, 2006
3) Edward F. Anderson “The Cactus Family” Timber Press, 2001
4) Larocca, J., Machado, M., Kiesling, R., Oakley, L., Pin, A. & Duarte, W. 2013. Frailea schilinzkyana. In: IUCN 2013. "IUCN Red List of Threatened Species." Version 2013.2. <www.iucnredlist.org>. Downloaded on 09 January 2014.
3) Bcher Gruppe "Frailea: Frailea, Frailea Cataphracta, Frailea Schilinzkyana, Frailea Gracillima, Frailea Amerhauseri, Frailea Pygmaea" General Books LLC, 2010

Cultivation and Propagation: Fraileas are are tiny plants with comparatively big yellow flowers, often bigger than the whole plant itself and are especially suitable for those with limited growing space. They can be easily grown in a sunny windowsill or a small greenhouse. The secret for keeping Fraileas happy and growing is to pot them in a rich, porous soil with good drainage and aeration, to give them lots of water and let them dry out between waterings. Fraileas do like more water than most other cacti. If you over-pot them (in about 6-7 cm pots) they grow much better and healthier, as they can be quite short-lived if not given correct growing conditions. During winter they like cool and dry places (minimum temperature of 5-10° C) but even light frosts do not harms them. Characteristically, during the dry season plants retract completely under the ground, both in the wild and in cultivation too. Occasional light spray of water during the winter helps plants from shrivelling up too much. In the summer they like the pot to be filled with rainwater (which is always better to use than tap water) quickly absorbed by the plants, and one can almost see the little bodies swelling up. After a day or two, it is best to drain off any remaining water in the under-pots.
Sun Exposure: They enjoy full sun. In a shaded position the plants grow faster, but are not flat shaped or dark coloured.
Propagation: With fresh harvested seeds or (rarely) by grafting. The seeds germinates well. Sow the them on the soil surface, so that they can grow to a reasonable size before they have to be pricked out into a bigger tray. The seed trays go into a heated propagator on a windowsill where they catch the afternoon sun. It does not take long for the seeds to germinate, and some will do so within a day or two after sowing. When they have reached a height of about 1 cm they are pricked out into a larger tray, where they remain until they are large enough to go into individual pots.