Q: What types of plants and flowers were in ancient gardens? What did they symbolize?

In the Medieval period, gardens were primarily utilitarian-- growing fruits, vegetables, and plants for medicinal use. However, in the Renaissance, despite the shift of use of the garden from utilitarian to ornamental, many plants were still cultivated with a purpose, whether it was symbolic or functional (http://www.vam.ac.uk/content/articles/i/italian-renaissance-villas-and-gardens/). In both the Medieval Period and the Renaissance, the types of ornamental flowers and plants cultivated often had a symbolic meaning behind them.

One of the most popular flower in the Renaissance and Medieval garden was the red rose. This flower was well-liked due to its pleasant aroma, aesthetics, and its notable symbolism. When Virgin Mary held the rose, it alludes to her role as the bride of Christ (http://www.metmuseum.org/toah/hd/bota/hd_bota.htm). This flower also represented the blood of martyrs, and became the Virgin Mary's special flower along with the Madonna lily. The white petals of the Madonna lily symbolised Mary's purity while the gold anthers represented the golden light of her soul (https://forum.disabroad.org/bbcswebdav/pid-197966-dt-content-rid-602993_1/courses/garden_1502213/05%20SP%2015%20The%20Mediæval%20Garden.pdf). Below are pictures of Medieval gardens-- red roses and lilies can be seen in both.

(https://forum.disabroad.org/bbcswebdav/pid-197966-dt-content-rid-602993_1/courses/garden_1502213/05%20SP%2015%20The%20Mediæval%20Garden.pdf)

(https://forum.disabroad.org/bbcswebdav/pid-197966-dt-content-rid-602993_1/courses/garden_1502213/05%20SP%2015%20The%20Mediæval%20Garden.pdf)

More religious symbolism comes from the beech tree and laurel tree. The breech tree derives from the Greek word meaning "to eat" because its acorns provided sustenance for ascetics, so the breech tree reminds the viewer of Christ's abstinence. The laurel was an attribute of the poet Apollo because he pursued Daphne until she metamorphosed into a laurel tree. Because of this, the laurel was the crown of poets. The laurel was also consecrated to the Vestal Virgins because of its evergreen properties. It was purity uncorrupted by decay. Laurel trees show up in religious paintings and gardens because of its meaning of chastity and immortality (http://www.metmuseum.org/toah/hd/bota/hd_bota.htm). The Renaissance Gardens of the Palazzo Piccolomini are shown below with many laurel trees planted.  

(http://upload.wikimedia.org/wikipedia/en/1/15/Piccolomini_Gardens.JPG)

A single plant or flower often had many meanings towards it because of the wealth and variety of source materials. A perfect example of a flower with multiple meanings is the carnation. The Greek name for the carnation means "flower of God," so the carnation usually appears in paintings of the Madonna and Child as seen below. 

(http://upload.wikimedia.org/wikipedia/commons/7/70/Leonardo_da_Vinci_Madonna_of_the_Carnation.jpg)

In particular, in the Northern Italian Renaissance paintings, a vase of carnations represented divine love. Similarly, in the Low Countries, a bride usually carried a pink carnation on her wedding day symbolising earthly love and marriage (http://www.metmuseum.org/toah/hd/bota/hd_bota.htm).

 Roses, lilies, laurel trees, beech trees, and carnations are a few examples of many flowers and trees with symbolism behind them planted in Renaissance and Medieval gardens. When studying ancient gardens, it is important to note the plants and flowers that were present because that could give rise to the meaning behind the garden (religious, herbal...etc).