When Are Cacti Found with Flowers and Fruits? Estimation of the Reproductive Phenology of the Genus Xiquexique Based on Herbarium Data

Abstract

Plant phenology reflects the reproductive responses of plants to seasonal cycles and climate change. Herbarium collections can be valuable tools for filling in gaps in phenological studies. We investigated the seasonality of the reproductive phenology of Xiquexique species using circular statistics, estimated their flowering and fruiting periods by interpolation via inverse distance weighting based on herbarium specimens (n = 290), and analyzed the relationships among phenophases, temperature, and precipitation using generalized linear models. Xiquexique species flowered and fruited throughout the year, with X. gounellei exhibiting peak flowering in February and peak fruiting in March, while X. tuberculatus exhibited those peaks in August–October and August, respectively, with decreased intensity during the austral winter. The maps produced through interpolation showed higher probabilities of flowering and fruiting between February and August at sites with mean annual rainfall rates between 500 and 800 mm. Temperature and precipitation were positively correlated with flowering. Xiquexique tuberculatus is important for providing continuous resources to pollinators and seed dispersers in the Caatinga. Herbarium collections and interpolation methods for filling in gaps concerning the reproductive ecology of Cactaceae can aid in better understanding altered phenological patterns resulting from environmental changes.