Identifying Small Round Cactus: Beyond Description
A 2.5" diameter round cactus with tiny spines in vertical rows and green vertical valleys could be one of hundreds of species. Visual identification requires photos.
Likely Genera for Description
Genus
Spine Arrangement
Body
Common Species
Mammillaria
Tubercles with radial/central spines
Globose to cylindrical
M. elongata, M. spinosissima
Rebutia
Small spines on tubercles
Clumping, flat-globose
R. minuscula, R. heliosa
Gymnocalycium
Few spines, chin-like areoles
Ribbed, shiny
G. mihanovichii, G. baldianum
Parodia
Dense spines, often hooked
Ribbed, globose
P. magnifica, P. leninghausii
Notocactus
Similar to Parodia
Ribbed, often tall
N. scopa, N. uebelmannianus
Photo Tips for ID
Top view (spine pattern)
Side view (rib/tubercle structure)
Close-up of areoles
Whole plant with ruler
Flower if blooming (huge ID help)
General Care While Unknown
Bright light, acclimate to direct sun
Water when dry (soak, drain, wait)
Cactus mix + extra perlite
Cool, dry winter rest (50°F, monthly water)
Email photos to experts or post on cactus forums. A photo is worth 1000 descriptive words for cactus ID.
