Description: The standard T. alonsoi is a small
geophytic solitary cactus with a large tap-root, and only the
apical part of the stem exposed at soil level. The crested form here
described is one of the rarest and priced crested cacti,
sought after by collectors but rarely on the trade.
Ribs: Arranged in tubercles, these are
15 mm long and 13 mm wide at the base, slightly angular, upper side
keeled, however concave at the base, clearly keeled on the
underside, arranged in spirals, from
grey-green to glaucous in colour.
Areoles: At first with reddish brown wool, later becoming
Spines 3-5, up to 20 mm long, flattened, cardboard-like, grey with
dark tip, irregularly bent inwards, frequently weathered, not
Flowers: Cherry red to pink-magenta, with more
intensely coloured mid-stripe 20-30 mm in diameter, 25-35 mm long,
standing above the tubercles by about 10 mm, with approximately 22 inner (teptals),
scale like perianth segments, more intensely red with pale edge. Pistil
15 mm long, white, standing above the stamens by around 2-4 mm, with 6
white, 1.5-2 (-2.5) mm-long stigma lobes.
Blooming season: From March to October, mainly between April and
Cultivation: Robust species to
cultivate. It requires full sun and careful watering to keep the plant
compact and low. It has a tap root, and watering it properly is often
difficult, because it tends to crack open or rot, if over-watered.
Propagation: by vegetative propagation grafting (usually) or