Libera, in her original Roman conception, was probably a goddess who presided over the fertility of women and especially the reception of semen (Spaeth 8). A representation of the female genitalia was allegedly kept in her temple. She is sometimes referred to as "the female Bacchus", perhaps because of her close association with the similarly named Liber. While not regularly associated with wine, a statue currently held in the British Musem pictures her holding a thyrsus, a spear bound with ivy or bay leaves, in her right hand, and a bunch of grapes in her left hand. She also wears a wreath of ivy on her head. The statue was found in Roma Vecchia, a suburb of Rome. Knight claims that ancient authors frequently used the name in Libera in referring to Bacchus, but this seems to be a confusion created by Libera's similarity in name to Liber (Knight 96.1). A link to an engraving of the Libera statue may be found here. The Columbia Encyclopedia claims that Libera was sometimes associated with Ariadne.
After the foundation of the Aventine Triad, she assimilated the mythology of the Greek Persephone, and was seen as the daughter of Ceres, who had assimilated the mythology of Demeter. A special cult devoted to the mother and daughter cropped up in Rome in the third century BCE. Libera in this aspect was often referred to as Proserpina (Spaeth 11). This cult emphasized the values of fertility and chastity, and were considered the primary virtues women needed to concern themselves with in Roman culture (12). This pair of deities were also propitiated when prodigies occurred (15). In the late imperial period, depicting departed Roman women in the guise of either Ceres, a mature woman, or Proserpina, a young woman, becomes a popular form of funerary statue to adorn tombs. Some scholars believe such a representation indicated that the deceased had been priestesses or at least devoted worshipers of the goddesses. Others merely suggest that the statues are used so that the deceased women could be memorialized in the type of the ideal mother and daughter (30).
The cult of Ceres and Proserpina was presided over by a woman, distinguishing it from the Italic cult of Ceres and the cult of the Aventine Triad (104). Cicero indicates that this woman, called the sacerdos Cereris or sacerdos Cerealis, would be an older woman of noble birth, whose character was considered highly respectable. She was the only woman, aside from the Vestal Virgins, allowed to have a position of power in a public cult. Cicero also indicates that there were certain rites of this cult that men were not admitted to, and that could only be performed by matrons and maidens (106).