Autor: (Schumann) Fric

“Southern Cactus”, because the genus is native to South America.
A genus of plants of medium size, little to strongly ribbed and tuberculate, with the apex depressed, solitary or forming clumps, becoming elongated. Areoles usually woolly, Spines mostly straight or flexible, exceptionally hooked (N. tenuicylindricus).
Flowers diurnal, sometimes self-fertile, usually quite wide, funnel-shaped, appearing around the apex, mostly yellow, but also pink, orange or purple, usually pollinated by hymenoptera: Andrenidae (Acamptopoeum prinii, Anthrenoides micans, Arhysosage cactorum, Callynochium petuniae, Psaenythia annulata, P. superba), Anthophoridae Ancyloscelis fiebrigii, Lanthanomelissa completa, Ceratina asunciana, C. hyemaiis, C. rupestris, C. volitans, Ptiiothrix fructifera), Apidae (Plebeia emerina, P. wittmannii), Colletidae (Cephaiocolietes rugata), Halictidae (Augochlora semiramis, Augochloropsis euterpe, Diaiictus sp.) Megachilidae (Lithurgus rufiventris), Schlindwein & Wittmann, 1995, 1997. Pistil stigmas usually red, but also pink, purple or orange. Fruits egg-shaped to globose, tenderly fleshy, lengthening mostly when ripe and drying, with a basal or longitudinal dehiscence; floral remains persistent. Seeds black, often bell or hat-shaped, rough, tuberculate. Dispersal of seeds ensured by ants.
The genus Notocactus has an extreme biodiversity due partially to its very wide geographic distribution and its ecology. According to species, it can grow in pockets of humus, on rocks or in crevices, among mosses, in the shade of woodlands, in rather humid forest areas but also in dry deciduous forests, grasslands (pampa), stony hills (cerros), on reddish rocky or sandy soils sometimes subject to temporary flooding, from sea level (N. scopa) up to 2800 m in altitude (N. mammulosus).
Argentina (Buenos Aires, Catamarca, Cordoba, Corrientes, Entre Rios, La Pampa, Mendoza, Misiones, Rio Negro, Salta, San Luis), Brazil (Parana, Rio Grande do Sul), Paraguay (Cordillera, Itapua, Paraguari), Uruguay (Artigas, Canelones, Cerro Largo, Durazno, Florida, Lavajella, Maldonado, Montevideo, Paysandu, Rivera, Rocha, Salto, Tacuarembo, Treinta y Tres).

Currently 29 recognised species + 13 possible subspecies.
– Notocactus allosiphon Marchesi 1972
– Notocactus arnostianus Usai & Kolarik 1986
– Notocactus buiningii Buxb. 1968
– Notocactus carambeiensis Burning & Brederoo 1973
– Notocactus concinnus* (Monv.) A.Berger 1929
– Notocactus concinnus subsp. agnetae (van Vliet) A.Doweld 2000
– Notocactus concinnus subsp. multicostatus (Burning & Brederoo) A.Doweld 2000
– Notocactus crassigibbus F.Ritter 1970
– Notocactus fuscus F.Ritter 1979
– Notocactus gauchus (M.Machado & Larocca) J.Lode 2013
– Notocactus herteri (Werderm.) Burning & Kreuzinger 1950
– Notocactus herteri subsp. roseoluteus (Vliet) J.Lode 2013
– Notocactus horstii* F.Ritter 1966
– Notocactus linkii* (Lehm.) Herter 1954
– Notocactus mammulosus* (Lem.) A.Berger 1929
– Notocactus mammulosus subsp. brasiliensis (Havlicek) J.Lode 2013
– Notocactus mammulosus subsp. erythracanthus (H.Schloss. & Brederoo) J.Lode 2013
– Notocactus mammulosus subsp. eugeniae (Vliet) J.Lode 2013
– Notocactus mueller-melchersii Fric ex Backeb. 1935
– Notocactus mueller-melchersii subsp. gutierrezii (W.R.Abraham) J.Lode 2013
– Notocactus mueller-melchersii subsp. winkleri (Vliet) J.Lode 2013
– Notocactus muricatus (Otto ex Pfeiff.) A.Berger 1929
– Notocactus neobuenekeri F.Ritter 1979
– Notocactus ottonis* (Lehm.) A.Berger 1929
– Notocactus oxycostatus Burning & Brederoo 1973
– Notocactus rauschii Vliet 1969
– Notocactus rudibuenekeri* Abraham 1988
– Notocactus rutilans Dan. & Krainz 1948
– Notocactus rutilans subsp. veenianus (Vliet) J.Lode 2013
– Notocactus schlosseri Vliet 1974
– Notocactus scopa* (Spreng.) A.Berger 1929
– Notocactus scopa subsp. marchesii (Abraham) Doweld 2000
– Notocactus scopa subsp. succineus (F.Ritter) Doweld 2000
– Notocactus stockingeri (Spreng.) A.Berger 1929
– Notocactus tabularis (Cels ex Rumpler) A.Berger & A.W.Hill 1933
– Notocactus tabularis subsp. bommeljei (Vliet) J.Lode 2013
– Notocactus tenuicylindricus* F.Ritter 1970
– Notocactus turecekianus (R.Kiesling) W.R. Abraham 1995
– Notocactus uebelmannianus Burning 1968
– Notocactus uebelmannianus subsp. pleiocephalus (N.Gerloff & Konigs) J.Lode 2013
– Notocactus vanvlietii Rausch 1970
– Notocactus werdermannianus Herter 1942

References: "TAXONOMY of the CACTACEAE" -  ISBN 978-84-617-3692-8 (Vol. 2)