The encyclopedia
Cactus genera & species
Every genus we cover, with all species, subspecies, varieties, and forms. Jump to a genus or scroll through.
Slow-growing, flat-bodied masterpieces of the Chihuahuan Desert. Among the most sought-after collector cacti in existence. All species CITES Appendix I.
species
The living rock. Most widely grown species. Extends into Texas.
subsp.
Distinct tubercle character. Occasionally in specialist trade.
species
Largest species. Reaches 20cm. Most variable in the genus.
A. retusus subsp. furfuraceus
subsp.
Woolly tubercle surfaces. Preferred by many collectors.
A. retusus f. cristata
f.
Cristate form. Exceptionally rare. Own-root specimens almost never seen.
species
Smallest Ariocarpus. Rarely exceeds 4cm. Requires perfect drainage.
species
Single population, Nuevo León. Boat-shaped tubercles unique in the genus.
species
Spine-tipped tubercles resemble a miniature agave. Gypsum specialist.
species
Recently separated from kotschoubeyanus. Includes subsp. hintonii.
subsp.
Distinct form. Restricted range within Nuevo León.
species
Only yellow-flowered Ariocarpus. Triangular upward-pointing tubercles.
Lophophora williamsii is the most notable one, known for it’s psychoactive or hallucinogenic alkaloid called mescaline.
species
Chihuahuan Desert. Most widely known species. Significant population decline from illegal collection.
species
Querétaro only. Pale green and spineless. More restricted range than williamsii.
species
Coahuila and Zacatecas. Most recently described species. More pronounced ribbing.
species
Described 2013. Jalisco and Nayarit. Status still debated by some authorities.
Native to the Atacama Desert, the driest non-polar desert on Earth. Slow, architectural, and increasingly rare from habitat destruction and illegal collection. CITES Appendix II.
species
Fewer than 1,000 individuals. Most evolutionarily distinct Copiapoa.
species
Miniature clustering species from the northern Atacama.
subsp.
Fewer than 800 individuals. AOO under 10km². No in-situ protection.
species
Cliff-growing. Distinctive abundant white wool. Road construction active threat.
species
Silver farina-covered stems. Can live 200 years.
subsp.
White spines. Collector demand documented as an extinction driver.
subsp.
Classic silver form around Taltal. Most available of the cinerea group.
species
Esmeraldas coast. Best habitat condition of any Copiapoa but range extremely narrow.
species
Partially subterranean. Unique growth habit among the genus.
var.
Distinct variety from Barquito. Sought by specialist collectors.
The largest cactus genus. We cover only the collector-grade rare end — species that remain almost unknown in cultivation despite the genus’s overall accessibility. CITES Appendix II.
species
Body almost entirely below ground. Disc-like form unique in the genus.
species
18 fragmented populations. Commercial collection confirmed as primary extinction driver.
species
Single volcanic-cliff population in northern Guanajuato; glassy white spine mat obscures the 3 cm heads.
species
Guanajuato endemic near San Luis de la Paz; ~500 individuals with plumose feathery white spines.
species
~430 individuals remaining. 95%+ lost to illegal collection. Cadereyta, Querétaro.
M. herrerae f. albiflora
f.
White-flowered form. Extremely rare even within this already critically rare species.
Mammillaria luethyi
species
44-year botanical mystery. Location kept secret. Now widely cultivated.
Mammillaria huitzilopochtli
species
Named after the Aztec god of war. Columnar clustering habit.
species
Described 2016. Fewer than 2,000 individuals. Hooked central spines.
Mammillaria crucigera
species
Cross-shaped spine pattern. Tehuacán-Cuicatlán Valley endemic.
Geometric perfection. Rare cultivars and Japanese hybrids command serious collector prices. A. asterias is CITES Appendix I; remaining species CITES Appendix II.
Astrophytum asterias
species
Federally Endangered in the US. Fewer than 4,000 in Texas. Widely cultivated since 1840s.
A. asterias f. nudum
f.
Spineless form without white flecks. Highly prized by collectors.
A. asterias f. variegata
f.
Yellow-sectored variegated form. Very high collector value.
Astrophytum caput-medusae
species
Described 2001. Snake-like tubercles completely unlike any other Astrophytum.
Astrophytum coahuilense
species
Dense white flecking. More restricted range than myriostigma.
Astrophytum myriostigma
species
Bishop’s cap. The most widely grown Astrophytum. Many cultivated forms.
A. myriostigma var. quadricostatum
var.
Four-ribbed form. Sought for its symmetrical geometry.
Spectacular nocturnal blooms and rare forms including cristate and monstrose mutations. Serious collector depth. CITES Appendix II.
Echinopsis ancistrophora subsp. ancistrophora
subsp.
Rocky Andean slopes. Among the rarest species-level Echinopsis in trade.
Echinopsis pachanoi f. cristata
f.
Crested San Pedro. Fan-shaped growth. Well-grown specimens genuinely scarce.
Echinopsis chamaecereus f. variegata
f.
Chlorophyll-deficient peanut cactus. Must be grafted to survive.
Tiny, threatened, and extraordinarily beautiful. Many species are critically endangered in their native San Luis Potosí. All CITES Appendix I.
Turbinicarpus alonsoi
species
Single known location. 500–2,000 individuals. Vivid pink flowers.
Turbinicarpus valdezianus
species
Feathery pectinate spines cover the body completely. One of the smallest.
Turbinicarpus boedekerianus
species
Flat-topped body with woolly crown. Very restricted limestone range.
Turbinicarpus lophophoroides
species
Spineless adult body resembles Lophophora. Distinct from all other Turbinicarpus.
Turbinicarpus pseudomacrochele
species
Long twisted spines. Central Mexico. Several recognised subspecies.
T. pseudomacrochele subsp. krainzianus
subsp.
Compact form with shorter spines. Highly sought by specialists.
Turbinicarpus saueri
species
Tamaulipas. Distinctive long white spines. One of the larger Turbinicarpus.
Only three species exist. Grows exclusively on near-vertical gypsum cliff faces in Nuevo León, Mexico. The rarest cultivated cactus genus in the world. All CITES Appendix I, all Critically Endangered.
Aztekium ritteri
species
The original Aztekium. Gypsum canyon walls. 7–10 years to flowering on own roots.
Aztekium hintonii
species
Larger and faster-growing than ritteri. Pink flowers. Galeana, Nuevo León.
Aztekium valdezii
species
Described 2011. Fewer than 500 wild individuals. Essentially uncultivated worldwide.
Bold, architectural barrels with spectacular spine forms. Certain species offer genuine collector appeal. CITES Appendix II.
Ferocactus viridescens
species
San Diego County and Baja. Threatened by coastal development. CNPS rare listing.
Ferocactus cylindraceus
species
Mojave and Colorado Deserts. Striking spines. Declining from renewable energy development.
Ferocactus glaucescens
species
Blue-grey body with yellow spines. Hidalgo, Mexico. Very popular in cultivation.
Ferocactus hamatacanthus
species
Hooked central spines. Chihuahuan Desert. Striking red-yellow spine contrast.
South American gems with subtle beauty. Rare forms include stunning variegates and colour mutations prized by collectors. CITES Appendix II.
Gymnocalycium buenekeri
species
Very restricted range in Rio Grande do Sul. One of the rarest Gymnocalycium in the wild.
Gymnocalycium horstii
species
Large flat-bodied with showy pink flowers. Declining from habitat loss.
Gymnocalycium mihanovichii
species
Parent of the moon cactus. Paraguay and Argentina.
G. mihanovichii f. variegata
f.
True own-root variegated form. Retains chlorophyll. High collector demand.
G. mihanovichii f. rubra
f.
The red moon cactus. Chlorophyll-free — must be grafted. Very widely known.