The earliest record that mentions Dorothea is found in the Martyrologium Hieronymianum. This first record contains only three basic facts: the day of martyrdom, the place where it occurred, and her name and that of Theophilus.
Legend
Virgin and martyr, Dorothea of Caesarea suffered during the persecution of Diocletian, 6 February, 311, at Caesarea in Cappadocia. She was brought before the prefect Sapricius, tried, tortured, and sentenced to death. On her way to the place of execution the pagan lawyer Theophilus said to her in mockery: “Bride of Christ, send me some fruits from your bridegroom’s garden.” Before she was executed, she sent him, by a six-year-old boy, her headdress which was found to be filled with a heavenly fragrance of roses and fruits. Theophilus at once confessed himself a Christian, was put on the rack, and suffered death. This is the oldest version of the legend, which was later variously enlarged. 
The oldest known version of the legend is Aldhelm’s De laudibus virginitatis, addressed to Abbess Hildelitha of
Barking Abbey, Essex. Kirsten Wolf characterizes it as one of several legends invented in the fourth and fifth centuries to provide a story to go with a name on one of the various liturgical calendars.
Veneration
In the West she has been venerated since the seventh century. Dorothy’s cult became widespread in Europe during the Middle Ages. In late medieval Sweden she was considered as the 15th member of the Fourteen Holy Helpers, and in art she occurred with Saint Barbara, Catherine of Alexandria and Margaret of Antioch, forming with them a quartet of female saints called de fyra huvudjungfrurna or in Latin, “Quattor Virgines Capitales” meaning “The four Capital Virgins”

Patronage
She is regarded as the patroness of gardeners. On her feast (February 6) trees are blessed in some places. She is also patroness of brewers, brides, florists, midwives, newlyweds and Pescia, Italy
Iconography Dorothea is represented with an angel and a wreath of flowers.
She is often depicted as a maiden carrying a basket of fruit and flowers, especially roses; also depicted wearing a
crown of flowers (such as roses); depicted surrounded by stars as she kneels before the executioner; crowned with palm and flower basket, surrounded by stars; depicted in an orchard with the Christ-child in an apple tree; leading the Christ-child by the hand; veiled with flowers in her lap; depicted holding apples from heaven on a branch.
-from Catholic.org