Fruit production and predispersal seed fall and predation in Rhamnus alaternus (Rhamnaceae)

Rhamnusalaternus Plant: Extraction of Bioactive Fractions and Evaluation of Their Pharmacological and Phytochemical Properties

Rhamnus alaternus, is a wild-growing shrub, belonging to the Rhamnaceae family. Widely distributed in the Mediterranean basin, R. alaternus is used in the usual medicine in numerous countries, mostly Tunisia, Algeria, Morocco, Spain, France, Italy, and Croatia. A large number of disorders-including dermatological complications, diabetes, hepatitis, and goiter problems-can be treated by the various parts of R. alaternus (i.e., roots, bark, berries, and leaves). Several bioactive compounds were isolated from R. alaternus, including flavonoids, anthocyanins, and anthraquinones, and showed several effects such as antioxidant, antihyperlipidemic, antigenotoxic, antimutagenic, antimicrobial, and antiproliferative. This review summarizes the updated information concerning the botanical description, distribution, extraction processes applied on R. alaternus, and its ethnopharmacology, toxicity, phytochemistry, and pharmacological effects.

Interspecific and annual variation in pre-dispersal seed predation by a granivorous bird in two East Asian hackberries, Celtis biondii and Celtis sinensis

Pre-dispersal seed predation by granivorous birds has potential to limit fruit removal and subsequent seed dispersal by legitimate avian seed dispersers in bird-dispersed plants, especially when the birds form flocks. We monitored pre-dispersal seed predation by the Japanese grosbeak, Eophona personata, of two bird-dispersed hackberry species (Cannabaceae), Celtis biondii (four trees) and Celtis sinensis (10 trees), for 3 years (2005, 2007 and 2008) in a fragmented forest in temperate Japan. Throughout the 3 years, predation was more intense on C. biondii, which, as a consequence, lost a larger part of its fruit crop. Grosbeaks preferred C. biondii seeds that had a comparatively lower energy content and lower hardness than C. sinensis, suggesting an association between seed hardness and selective foraging by grosbeaks. In C. biondii, intensive predation markedly reduced fruit duration and strongly limited fruit removal by seed dispersers, especially in 2007 and 2008. In C. sinensis, seed dispersers consumed fruits throughout the fruiting seasons in all 3 years. In C. biondii, variation in the timing of grosbeak migration among years was associated with annual variation in this bird's effects on fruit removal. Our results demonstrate that seed predation by flocks of granivorous birds can dramatically disrupt seed dispersal in fleshy-fruited plants and suggest the importance of understanding their flocking behaviour.

Unripe red fruits may be aposematic

The unripe fruits of certain species are red. Some of these species disperse their seeds by wind (Nerium oleander, Anabasis articulata), others by adhering to animals with their spines (Emex spinosa) or prickles (Hedysarum spinosissimum). Certainly neither type uses red coloration as advertisement to attract the seed dispersing agents. Fleshy-fruited species (Rhamnus alaternus, Rubus sanguineus and Pistacia sp.), which disperse their seeds via frugivores, change fruit color from green to red while still unripe and then to black or dark blue upon ripening. The red color does not seem to function primarily in dispersal (unless red fruits form advertisement flags when there are already black ripe fruits on the plant) because the red unripe fruits of these species are poisonous, spiny, or unpalatable. The unripe red fruits of Nerium oleander are very poisonous, those of Rhamnus alaternus and Anabasis articulata are moderately poisonous, those of Rubus sanguineus are very sour, those of Pistacia sp. contain unpalatable resin and those of Emex spinosa and Hedysarum spinosissimum are prickly. We propose that these unripe red fruits are aposematic, protecting them from herbivory before seed maturation.