Flora is the Roman Goddess (She's called Chloris in Greek lore) of flowering plants, especially those that bear fruit. Spring, of course, is Her season, and She has elements of a Love-Goddess, with its attendant attributes of fertility, sex, and blossoming. She is quite ancient; the Sabines are said to have named a month for Her (which corresponds to our and the Roman April), and She was known among the Samnites as well as the Oscans, where She was called Flusia. She was originally the Goddess specifically of the flowering crops, such as the grain or fruit-trees, and Her function was to make the grain, vegetables and trees bloom so that autumn's harvest would be good. She was invoked to avert rust, a nasty fungal disease of plants that causes orange growths the exact color of rusting iron, and which was (is) an especial problem affecting wheat. Hers is the beginning of the process that finds its completion with Pomona, the Goddess of Fruit and the Harvest; and like Pomona, Flora had Her own flamen, one of a small number of priests each in service to a specific Deity. The flamens were said to have been instituted by Numa, the legendary second King of Rome who succeeded Romulus; and whether Numa really existed or not, the flamens were undoubtedly of ancient origin, as were the Deities they served.
In later times Flora became the Goddess of all flowering plants, including the ornamental varieties. Her name is related to Latin floris, meaning naturally enough "a flower", with the additional meaning of "[something] in its prime"; other related words have meanings like "prospering", "flourishing", "abounding", and "fresh or blooming". In one story, Flora was said to have provided Juno with a magic flower that would allow Her to conceive with no help from a man; from this virgin-birth Mars was born. A late tale calls Flora a courtesan and gives Her a story similar to Acca Larentia: Flora was said to have made a fortune as a courtesan, which She bequeathed to Rome upon Her death, and for which She was honored with the festival of the Floralia. As Flora was originally a Sabine Goddess, and as the Sabines were a neighboring tribe whom the Romans conquered and assimilated into Rome, perhaps this is an acknowledgement of the land so acquired, put into legendary terms.
Flora had two temples in Rome, one near the Circus Maximus, the great "stadium" of Rome where chariot races were held, and another on the slopes of the Quirinal Hill. The temple on the Quirinal was most likely built on the site of an earlier altar to Her said to have been dedicated by Titus Tatius, King of the Sabines, who ruled alongside Romulus for a time in the very early (hence legendary) days of Rome. Her other temple was built quite near to the Circus Maximus, though its exact site has not been found, and was associated with a neighboring temple dedicated to the triad of Ceres (the Grain Goddess) and Liber and Libera (God and Goddess of the Vine). These Deities and Flora were all concerned with the fertility and health of the crops. Flora's temple by the Circus was dedicated on the 28th of April in 241 (or 248) BCE in response to a great drought at the command of the Sybilline books, and this day became the starting date of Her great festival, the Floralia. In Imperial times (1st century CE) this temple was rededicated (I assume after some restorations were made) on the 13th of August, and this date was given to a second festival of Flora, coinciding with the ripening of the grain, whose flowers She had set forth.
The Floralia of April was originally a moveable feast to coincide with the blossoming of the plants, later becoming fixed with the dedication of Her temple on the 28th (or 27th, before the calendar was reformed--I mention this because holidays were almost always held on odd-numbered days as it was considered unlucky to start a festival on an even-numbered day), though ludi or "games"--horse-races or athletic contests--were not held every year. By the Empire the festival had grown (or should I say, blossomed) to seven days, and included chariot-races and theatrical performances, some of which were notoriously bawdy. It was given over to merriment and celebrations of an amorous nature, much like that northern flower-and-sex festival Beltaine whose date neatly coincides. Prostitutes considered it their own special time, and the Floralia gained a reputation as being more licentious and abandoned than the Saturnalia of December, whose name is legendary even now.
At the chariot-races and circus games of the Floralia it was traditional to let goats and hares loose, and lupines, bean-flowers and vetch (all of which have similarly-shaped blossoms and are a sort of showier version of wheat in bloom) were scattered, symbolic of fertility. Brightly colored clothes were a must, as were wreaths of flowers, especially roses; and the celebrations drew great crowds. Of the two nationalized chariot-teams who shared a deep rivalry, the Greens and the Blues, the Greens (of course) were Hers, and She had been invoked at chariot-races from ancient times. The last day of the festival, May 3rd, was called Florae; it may be a special name for the closing day of the Floralia, or it may refer to a seperate ceremony conducted in Her temple on the Quirinal.
Flora was depicted by the Romans wearing light spring clothing, holding small bouquets of flowers, sometimes crowned with blossoms. Honey, made from flowers, is one of Her gifts, and Her name is said to be one of the secret (holy) names of Rome. She is sometimes called the handmaiden of Ceres. Ovid identifies Her with the Greek flower-nymph Chloris, whose name means "yellow or pale green", the color of Spring. The word flora is still used as a general name for the plants of a region.
Alternate names/epithets: Flora Rustica, "Flora the Countrywoman" or "Flora of the Countryside", and Flora Mater, or "Flora the Mother", in respect to Her ancient origins. Among the Oscans She was known as Flusia.