Genus scope and naming history
In the Plants of the World Online treatment checked on 9 October 2026, Tacinga includes 11 accepted species and four named hybrids. The species are T. armata, T. braunii, T. funalis, T. gladispina, T. inamoena, T. lilae, T. mirim, T. palmadora, T. saxatilis, T. subcylindrica and T. werneri. The most recently described is T. mirim from Ceará, published in 2024. [2-WWW] [Menezes and Alves 2024]
The genus was described in 1919 for Tacinga funalis. Transfers of species from the broadly circumscribed Opuntia fundamentally changed its boundaries. The names Opuntia inamoena, O. palmadora, O. saxatilis, O. werneri and O. lilae now lead to the corresponding Tacinga species. T. subcylindrica was formerly treated as a subspecies of T. inamoena. Earlier identifications of T. palmadora from Ceará require specimen checks because some refer to T. mirim. [Menezes and Alves 2024] [Majure et al. 2013] [Barrios-Leal et al. 2024]
POWO accepts the name Tacinga ×catingicola (formerly Opuntia ×catingicola, and Tacinga paiaia in the description from 2023) for the hybrid T. palmadora × T. werneri. The new combination was published in 2024. The other accepted hybrid names are T. ×flammea, T. ×grandiflora and T. ×quipa. The × sign indicates the hybrid origin of these taxa. They are distinguished from the 11 species in the genus list. [2-WWW]
Structural characters and relationships
In many species, short, flattened segments form low shrubs or dense clumps. T. funalis and T. braunii have much longer, often cylindrical stems that lean on the surrounding vegetation. Areoles produce glochids and, in some species, larger spines. The particularly strong armature of T. armata also covers young fruits. Flower, mature fruit and seed structure provide diagnostic characters even when plant habits are similar. [Menezes and Alves 2024] [Freitas et al. 2021]
The analysis from 2013 combined plastid and nuclear data with reconstruction of morphological characters. It identified a set of traits characteristic of the Tacinga lineage studied, including a hook-shaped embryo, a particular proportion of perisperm in the seed, stomatal apparatuses raised above the surrounding epidermis, and a deep, narrow depression at the fruit apex. A hairy covering of funicular origin also occurs in other opuntioids and represents a broader inheritance of this group. [Majure et al. 2013]
The basic chromosome number is x = 11. Documented counts in the genus include diploid T. palmadora (2n = 22), tetraploid T. mirim and T. gladispina (2n = 44), hexaploid T. lilae and T. armata (2n = 66), and pentaploid T. ×flammea (2n = 55). Chromosome number helps recognise distinct taxa and assess hypotheses of their origin. Establishing whether a polyploid arose by duplication of its own genome or by crossing distinct lineages also requires data on genome ancestry. [Menezes and Alves 2024] [Majure et al. 2013] [Freitas et al. 2021]
Habitats and geography
Most species occur in eastern Brazil, primarily in the seasonally dry communities of the Caatinga. Their habitats include shallow soils on rock, crevices in outcrops, sandy substrates, scrub and dry forests. New, verified specimens of T. saxatilis subsp. saxatilis from Goiás and Tocantins extended this plant’s documented range to limestone outcrops within the Cerrado. [Menezes and Alves 2024] [Freitas et al. 2021] [Gonzaga et al. 2023]
Tacinga lilae (formerly Opuntia lilae) occurs in Venezuela, about 3000 km from the northeastern Brazilian part of the genus’ range. Its placement in Tacinga is supported by DNA sequences and seed, fruit and epidermal characters. Explanations considered for this geographical gap include former continuity of dry communities and long-distance dispersal. The study did not resolve these scenarios. [Majure et al. 2013]
Flowering, recruitment and animals
The group includes orange, red, yellow and greenish flowers. The structure of many favours hummingbird visits, but the actual visitor composition depends on species and site. Bee visits predominated in a collection of T. inamoena in Rio de Janeiro. Assessing a pollinator also requires measurement of pollen transfer or its contribution to seed production. Contact with floral structures alone documents a visit. [Majure et al. 2013] [Gonzaga et al. 2025]
Vegetative recruitment can use two kinds of propagules, detached segments and fruits capable of producing new shoots. Such regrowth from fruits has been described in T. lilae, T. mirim, T. armata and T. gladispina. In T. mirim, shedding of terminal segments increases during the dry season. A fruit can therefore combine protection of seeds with a role in clonal expansion. [Menezes and Alves 2024] [Majure et al. 2013] [Freitas et al. 2021]
Flowers of T. inamoena are also food for lizards. Destruction of the ovary enclosed by the pericarpel removes the possibility of fruit formation from that flower. If parts of the tepals or stamens are eaten, a fruit may still develop. Comparison of field observations from Rio Grande do Norte with a collection in Rio de Janeiro shows how the location of damage changes the outcome of florivory. [Paixão et al. 2021] [Gonzaga et al. 2025]
Genetic variation and future habitats
A study of 222 plants of T. inamoena, T. subcylindrica and T. palmadora showed clear differentiation among these species, with little variation in the markers studied within species. Two plastid DNA regions and the nuclear gene PhyC were analysed. The results support the distinctness of T. subcylindrica, formerly treated as a subspecies. Demographic reconstructions depended on the method and did not unequivocally confirm population growth. [Barrios-Leal et al. 2024]
Distribution models from 2024 project a reduction in climatically suitable area for T. inamoena and T. palmadora. The magnitude of change depends strongly on the algorithm. For T. inamoena under the SSP5 scenario covering 2061–2080, the decline was 64,52% in Maxent and 19,6% in BRT. These are projections of potential habitat area based on one global climate model. Their unit is neither the number of individuals nor an experimentally determined thermal tolerance limit. [Sampaio et al. 2024]