Gymnocalycium triacanthum P124, Sierra Ancasti, Catamarca, Argentina
Forms flat greyish/brow to olive/green stems with (usually) three
spider like spines per areoles, it is fairly rare in cultivation but
easy to grow.
Description: G. triacanthus (rionense)
is a dark skinned solitary Argentinian cactus with almost useless spines
making it relatively easy to handle. G.
rionense is one of the most variable Gymnocalycium. Will eventually
offset after a considerable period of time.
Stem: Flattened globose, brownish olive green, 1-8 cm tall up to
10 cm in diameter. Apex depressed often spineless.
Ribs: 10-12, flattened,
without prominent chin-like protrusions..
Areoles: Oval with white felt.
Spines: All radials 3 (to 7) yellowish-white to light-brow with
dark tips when young,
becoming grey with age, spider-like,
slightly curved, flattened against the stem, one pointing downward the
other to the sides, up to 2 cm long.
Flower: White to pinkish-brown with a pale pink or red center up
to 3,5 cm across, tube short.
Blooming season: Flowers are produced in late spring and remain
open for up to twelve days.
Cultivation: Summer grower,
water regularly in summer, keep this plant almost dry in winter at a
minimum temperature of 0°C, prefer a
growth will stop altogether. The plant does not like
extremely bright situations. Give it some shade during the hottest
part of the day.
Propagation: Direct sow after
last frost. (seldom
Fruit must be significantly
overripe before harvesting seed; clean and dry seeds
triacanthum, Backeberg 1959
In: Die Cactaceae 3:1784, 1959
nom. Inval. Art. 8,2, 37.1( = G. Marsoneri subs. matoense)
Scientific name: Gymnocalycium
riojense Fric ex Till & Till
Origin: Argentina (Cordoba, Catamarca,
Conservation status: Listed in
CITES appendix 2.
Etymology: The species name "triacanthum"
comes from the Greek for "with 3 spines".
- Gymnocalycium riojense
Fric ex H. Till & W. Till 1991
- Gymnocalycium stellatum
- Gymnocalycium asterium var.
triacanthum Rowland SL1992
- Gymnocalycium rionense subs.
Paucispinum var. triacanthum
- Gymnocalycium triacantum
Some authors recognizes
several (controversial) variety of G. rionense, differing
in spination, body shape and distribution:
- The 'riojense' subspecies. It is
the more widespread and common it has 5 radial spines and whitish to
pinkish brown flowers. (Origin: La Rioja)
- The 'kozelskyanum' subspecies has
3 radial spines and the flowers are deep pink with darker throats
(Origin: Sierra de los Colorados).
- The 'paucispinum' subspecies has
3 radial spines and white/off white blooms.(Origin: La Rioja)The 'piltziorum'
subspecies has 3-5 radial spines that are initially erect then
radiate. The flowers are lilac-pink. (origin:Sierra Velasco)
- The 'platygonum' subspecies has
pearl-white scented flowers and 3 claw-shaped spines.(Origin: N
Photo of conspecific
taxa, varieties, forms and cultivars of plants
belonging to the Gymnocalicyum