Clumping small barrel cactus, that forms powerful colonies of hundreds
of branches, reaching over 90-100 cm high and 3(-5) m wide. The
remarkable polycephalic habit of Ferocactus robustus is quite unlike
that of any other species in the genus. These clusters are probably not
from the same original root system, but are a complex which has
developed from seedling plants which have grown up around the parent.
Stems: The individual stem are some of the smallest of the genus,
globular to clavate, smooth, shiny dark green to red-grey, 8 to 16 cm
wide (rarely exceed 20 cm of diameter).
Areoles: Few and widely
separated on the ribs, approx 8 mm in diameter in diameter, with an
upper flowering portion, whit short dull white felt, becoming
inconspicuous in age.
Ribs: Up to 8., prominent, acute, thickened under areoles,
Central spines: 4-6 brown, redish or horn-coloured coloured,
erect, radiating, straight, annulate, square or angled in cross section,
sometimes flattened laterally, the lower one longer up to 6 cm long.
Radial spines: Needle-like, approx 10-14 , the lower ones much like
the centrals and the upper ones acicular or bristle-like and lighter in
Flowers: Yellow to yellow-orange, 3-4 cm in long and in diameter.
Ovary covered with broad, rounded imbricated scales, these intergrading
into the outer perianth segments; outer perianth segments yellow with
red midstripe, mucronate; inner perianth segments yellow, oblong, acute;
stigma lobes 10, red.
Blooming season: Spring and autumn .the blossoming period is long.
Fruit: 20-30 mm tall, 20 mm in diameter, yellow, with broad,
widely separated, fleshy scales.
Seeds: Black 1,5 mm long and 1 mm wide, finely sculptured with