Tacinga inamoena

Name and identification

Tacinga inamoena (formerly Opuntia inamoena) is an accepted species within the opuntioids. Current treatments separate it from T. subcylindrica, previously described as a subspecies. Differences include segment shape, habit and genetic data. In the newer key, the similar T. gladispina is additionally distinguished by stiff spines with a flattened base. [Barrios-Leal et al. 2024] [Freitas et al. 2021] [2-WWW]

The stems are flattened and form low clumps, usually reaching about 50 cm tall. Large spines are reduced, while areoles retain numerous glochids. Flowers are orange, and globular or slightly flattened fruits ripen to shades of yellow and orange. A tetraploid count of 2n = 44 has been documented. Variation in karyotype characters among the populations studied was compiled in the comparative review of the genus. [Menezes and Alves 2024]

Habitats and genetic variation

The species is widespread in the Brazilian Caatinga. It occupies various rocky sites and stony soils in seasonally dry communities. The population study included 148 plants from 34 locations, the largest sample among the three Tacinga species analysed. Two plastid DNA regions and the nuclear gene PhyC revealed low variation within the species and distinctness from T. palmadora and T. subcylindrica. [Barrios-Leal et al. 2024]

Some plastid samples showed double sequencing signals, interpreted as possible heteroplasmy, the coexistence of different plastid genome variants. The authors considered several sources of this phenomenon, including unusual plastid inheritance and past hybridisation. Ambiguous positions were excluded from some analyses. The result leaves open the question of how the observed variation arose. [Barrios-Leal et al. 2024]

Flowers and their visitors

In 2021, 79 flowers were observed in the botanical garden collection in Rio de Janeiro. They opened before 6, were fully open around 7, and closed between noon and 14. Anthesis, the period of flower opening, lasted one day. Over 110 hours, bee visits predominated, including 68 visits by Trigona, alongside five visits by the hummingbird Thalurania glaucopis. This visitor composition refers to a specific collection outside the natural habitat. [Gonzaga et al. 2025]

Initially, 72 fruits formed, of which 11 subsequently fell off. From the 79 flowers observed, 61 fruits matured. Fruit initials also appeared in a small sample of bagged flowers. This provides grounds for further study of self-pollination and self-fertility. Identifying how embryos form requires separate experiments with controlled pollination and seed assessment. [Gonzaga et al. 2025]

In a natural population in Rio Grande do Norte, camera traps recorded four cases of flower consumption by the lizard Tropidurus hispidus among 53 monitored flowers. In three cases, destruction of the whole flower or severe damage to its reproductive organs resulted in no fruit. Partial consumption of the perianth had a less severe outcome. In the Rio de Janeiro collection, T. torquatus left the pericarpel intact, and damaged flowers often formed fruits. [Paixão et al. 2021] [Gonzaga et al. 2025]

Seed storage and germination

An experiment using seeds from São João do Cariri in Paraíba compared paper bags with sealed glass containers and two storage temperatures, 8 ± 1°C and 24 ± 2°C. Samples were taken initially and after 12, 16 and 20 months. Germination was assessed on moist paper at 25 ± 1°C under constant illumination for 30 days. These are the seed storage and laboratory test conditions. [Silva et al. 2023]

Initially, 14% of seeds germinated. After cool storage, values were about 14–28%, depending on the sampling time and packaging. They declined markedly in warm storage, and seeds in paper bags after 16 and 20 months did not germinate in the test used. Cooling better preserved the fraction capable of germination. The low initial result means the experiment primarily provides storage data, while the causes of dormancy and incomplete development in some seeds remain unresolved. [Silva et al. 2023]

The authors also recorded polyembryony, visible as more than one seedling developing from a single seed. They did not determine its frequency in the entire population or the genetic origin of the embryos. The observation documents a developmental phenomenon, while its connection with possible apomixis remains a separate research question. [Silva et al. 2023]

Glochids and microorganisms

Glochids have small projections directed towards the base that help them lodge in tissues. A case study of sheep and goats in Paraíba found glochids of T. inamoena in the cornea, conjunctiva and inflammatory lesions of the mouth. Histological material showed foreign bodies surrounded by cells of the inflammatory response. Glochids remain an important mechanical feature of this plant despite the limited development of large spines. [Pequeno et al. 2021]

Fungi described as Bezerromyces brasiliensis, B. pernambucoensis and Xiliomyces brasiliensis were isolated from internal tissues of plants from Pernambuco. Identification was based on cultures, the structure of sporulating organs and DNA sequence analysis. The study documents endophyte diversity. The functions of these particular fungi in water relations or host protection require separate experimental studies. [Bezerra et al. 2017]

Application studies

Experiments using material from this species are presented in the “Biotechnology and applications” section. Bacteria from the cactus surface and cucumber seedling growth. [Pereira et al. 2026]