• ETYMOLOGY
In Greek, ≪top cactus≫, referring to the characteristic top-shaped form of the plants in this genus. • DESCRIPTION
A genus of plants usually solitary, sometimes branched, hemicryptophytic, sclerotic, globose, turbinate or cylindrical, the apex strongly depressed and woolly. Ribs absent, tubercles imbricated and spiralled, rhomboid flattened, keeled at the base; areoles woolly, garnished with 1-4 flexible spines emerging, deciduous over time.
Flowers diurnal, (self-sterile?), appearing at the apex, funnel-shaped, pale yellow or pink magenta, pollinated by bees. Fruits elongated, naked or scaly, somewhat fleshy, pale red magenta, with longitudinal dehiscences (only one in S. corregidorae), releasing freely the seeds. Seeds tiny, globose to almost pear-shaped, brown, with a large, whitish strophiola, absent in S. corregidorae. Seed dispersal ensured by ants. • HABITAT
The genus Strombocactus grows in limited habitats but often in large numbers and as a mimetic plant, in canyons, on vertical cliffs, or very oblique faces, on arid limestone soils consisting of clastic sediments with fine particles (lutites), almost completely devoid of vegetation or in a xerophytic scrub (matorral), from 950 up to 2000 m in altitude. • DISTRIBUTION
Mexico (Guanajuato, Hidalgo, Queretaro).
Currently 2 recognised species + one subspecies:
– Strombocactus corregidorae* Arias & Sanchez 2010
– Strombocactus disciformis* (DC.) Britton & Rose 1922
– Strombocactus disciformis subsp. esperanzae Glass & Arias 1996 (= S. pulchra)
• ETYMOLOGY
Genus honouring Francis Lynde Stetson (1846-1920), of New York, who was a lawyer fascinated by botany. He was also an administrator of the New York Botanical Garden. • DESCRIPTION
A monotypic genus of massive treelike plants reaching up to 8 m high, strongly branched (up to 100 or more), with a thick, well defined trunk, 40 cm in diameter and with branches erect or arching. Stems bluish green, club-shaped, not segmented, ribs 8-9, thick, more or less crenate. Areoles woolly; about 7-9 radial spines 3 cm long; 1 central spine which can reach 7 cm or more, straight and sharp.
Flowers nocturnal, self-sterile, but remaining open until the next day, funnel-shaped and widely spread, with pericarpel and long floral tube scaly, white, fragrant, pollinated by Sphingideae. Fruits globose to egg-shaped, fragrant, green tinged with red, edible, covered with scales, the remains of the dried perianth deciduous. Seeds rather small, roughly egg-shaped to cochleariform (spoon-shaped), brown to black, shiny, rough and warty. Seed dispersal assured by among others and in some specific regions – the tapir (Tapirus terrestris). • HABITAT
The monotypic genus Stetsonia grows in large but scattered colonies, at low or medium altitude, generally from 100- 900 m and more, rarely up to 2200 m in altitude, in dry areas, on hills, mountain slopes or shrubby pampas in Bolivia, in the deciduous dry forests of Paraguay, or arid plains of north-western Argentina, in Chaco, together with Cereus forbesii and Opuntia quimilo. • DISTRIBUTION
Argentina (Catamarca, Cordoba, Chaco, Corrientes, Formosa, Jujuy, Rioja, Salta, Santiago del Estero, Santa Fe), Bolivia (Santa Cruz, Tarija), Brazil (Rio Grande do Sul), Paraguay (Alto Paraguay, Boqueron, Concepcion, Presidente Hayes).
Currently only one recognised species:
– Stetsonia coryne* (Salm-Dyck) Britton & Rose 1920
• ETYMOLOGY
“Crowned cereus”, referring to the characteristic annular cephalium of the unique species in this genus. • DESCRIPTION
A monotypic genus of columnar plants, mostly solitary, rarely branched, reaching 2-5m high, with st;ems irregularly segmented according to new growth, bluish green, 13-18 straight ribs. Areoles close-set, strongly woolly, provided with 20 very short and white radial spines, and 1-2 longer and more stiff central spines, golden yellow. Annular cephalium densely woolly and hairy.
Flowers nocturnal, (self-fertile? pers. obs.) tubular to bell-shaped, appearing laterally, as well on the terminal cephalium as on former ones, creamy-white, pollinated by bats, also by hymenoptera. Fruits elongated, thick-walled, becoming bluish covered with wax when ripe, with white or red pulp. Seeds warty, black, dull, retaining an envelope of mucilage. Seed dispersal ensured by bats and ants. • HABITAT
The monotypic genus Stephanocereus grows endemically in Brazil, between 270 m and 750 m in altitude, on variable soils, blocks of rocks, in crevices, on rocky outcrops, on quartz sands, among grasses and bushes, also in the caatinga, among the bushes where it emerges. • DISTRIBUTION
Brazil (Bahia).
Currently only one recognised species:
– Stephanocereus leucostele* (Guerke) Berger 1926
• ETYMOLOGY
“Narrow cereus”, referring to the ribs of most species within the genus, which are narrow. • DESCRIPTION
A genus of treelike or shrubby, columnar, erect, pendulous or exceptionally creeping (S. eruca) plants, sometimes forming impenetrable thickets (S. gummosus), usually strongly branched, some species from the base, others irregularly branched, sometimes forming a trunk. Stems sturdy, with ribs often numerous, mostly tuberculate, areoles woolly. Radial spines spread, 1-4 central spines, usually sturdy, sometimes flattened like a dagger.
Flowers usually nocturnal in most species, sometimes remaining open until the next day, rarely diurnal (S. alamosensis), often scented, funnel-shaped or bell-shaped, with scaly and often spiny pericarpel, pollinated at night by bats (Anoura geoffroyi, Antrozous pallidus, Artibeus jamalcensis, Carollia sp, Choeronycteris mexicana, Glossophaga commissarisi, G. leachii, G. longirostris, G. soricina, Leptonycteris curasoae, L nivalis, L. sanborni, L. yerbabuenae, Phyllostomus discolor), in the daytime, by hummingbirds (Amaziiia beryliina, A. rutila, A. violiceps, Archilochus colubris, Caiypte costae, Cynanthus latirostris, C. sordidus, Eugenes fulgens, Lampornis clemenciae, Phaetornis superciliosus, Selasphorus rufus), other birds (Auriparus flaviceps, Colaptes auratus, Icterus gularis, I. pustulatus, Melanerpes aurlfrons, M. hypopolius, M. uropygialis, Toxostoma curvirostre, Zenaida asiatica, Z. macroura), bees (Agapostemon sp., Apis mellifera, Bombus sp., Halictus sp, Melipona sp., Scaptotringona sp., Trigona sp.) and a butterfly (Hamadryas sp.). Fruits globose or egg-shaped, more or less fleshy according to species,usually edible and consumed by the local populations, with deciduous spines when ripe, usually not retaining the remains of the dried perianth. Seeds rather large, obovoid, black, shiny, generally smooth, but also warty, tuberculate or pitted. Dispersal of seeds provided by bats, birds, and also lizards (Sceloporus orcuttii on Stenocereus thurberi, pers. obs.) and small mammals. • HABITAT
Given its great biodiversity, the genus Stenocereus grows in varied habitats, in hot, dry regions and sandbanks, stony deserts and plateaus, in canyons, rocky or sandy hills, on red lavas, at the edge of cliffs, on sandy alluvial plains in the matorral, xerophytic scrub formed by spiny bushes, near coastal areas, from sea level (S. eruca), up to 2120 m in altitude (S. stellatus), together with other cacti (Mammillaria, Pachycereus, Echlnocereus, Corynopuntia, Opuntia) and bromeliads. • DISTRIBUTION
Colombia (Boyaca, Cesar, Guajira, Magdalena), Cuba, Guatemala (Baja Verapaz, Chiquimula, El Progreso, Huehuetenango, Jutiapa, Quiche, Zacapa), Mexico (Aguascalientes, Baja California, Campeche, Chiapas, Chihuahua, Colima, Guanajuato, Hidalgo, Guerrero, Jalisco, Mexico D.F., Michoacan, Morelos, Nayarit, Oaxaca, Puebla, Queretaro, San Luis Potosi, Sinaloa, Sonora, Zacatecas), Puerto Rico, Dominican Rep., USA (Arizona, California), Venezuela (Sucre).
• ETYMOLOGY
“Dry fruit” characteristic of the fruit of this genus, which dries when ripe. • DESCRIPTION
A genus of columnar plants with erect stems, usually solitary, bluish, with a very woody vascular cylinder, with a continuous and deeply sunken cephalium, developing when the stem exceeds one metre, densely furnished with white wool, with long yellow or reddish bristles. Areoles ovate, densely woolly. Spines aciculate, straight, strongly developed at the base of stems.
Flowers nocturnal, self-sterile, funnel-shaped to bell-shaped, ivory white, pollinated by bats (Monophyllus redmani, Phyllonycterispoeyi). Fruits first sunken into the cephalium, bluish, thin-walled, dry, basally dehiscent, with remnants of the perianth deciduous, not darkening. Seeds brown, very irregularly elongated, with a cellular testa. Anemophilous dispersal reported for S. dolichospermaticus (Taylor & Zappi 2004). • HABITAT
The genus Siccobaccatus grows endemically in Brazil, from 400 m up to 760 m in altitude, usually on broken rocks or limestone outcrops (Bambui formation), sometimes in dense populations (S. estevesii), to the edge of tropical dry woodlands with a spiny vegetation (caatinga). Their cephaliums are always oriented in the same direction, the northwest (southern part of the American continent). They are often found together with bromeliads and other cacti such as Meiocactus. • DISTRIBUTION
Brazil (Bahia, D.F., Goias, Minas Gerais, Tocantins).
Autor: Braun & Esteves Pereira