It is often repeated that Aphrodite first planted Marjoram in her divine gardens on Mt Olympos. The plant was to represent joy, and in turn because of its association with Aphrodite the herb corresponds with marriage and happiness. It is also said to smell reminiscent of the goddess herself.
Marjoram is indigenous to Cypris, Turkey, and the Mediterranean, and was in fact known to the ancient Greeks and Romans as a symbol of happiness. It's botanical name, origanum, is perhaps derived from the words oros 'mountain' and ganos 'brightness', meaning 'brightness of the mountain’ or ‘mountain’s bright joy.’ [1]
Marjoram and Oregano are often mistaken and their names were used interchangeably in ancient texts - either as sampsuchum or amaracus, though there are some subtle differences between the use and description of the two. It is generally assumed that both refer to Sweet Marjoram in ancient texts. [2]
When discussing perfumes in his encyclopaedia Natural Histories XIII, Roman author and naturalist Pliny the Elder says, 'The best [marjoram for perfume oils] comes from Cyprus and Mytilene, where sampsuchum abounds in large quantities,' [3] which is why there is such a strong association of marjoram with Cypris and therefore Aphrodite. Marjoram was used often in sweet oils and perfume ointments, as well as it's more common culinary and medicinal uses.
[...] She went to Cyprus, to Paphos, where her precinct is and fragrant altar, and passed into her sweet-smelling temple. There she went in and put to the glittering doors, and there the Graces bathed her with heavenly oil such as blooms upon the bodies of the eternal gods —oil divinely sweet, which she had by her, filled with fragrance. And laughter-loving Aphrodite put on all her rich clothes, and when she had decked herself with gold, she left sweet-smelling Cyprus and went in haste towards Troy, swiftly travelling high up among the clouds. [...]
- Homeric Hymn to Aphrodite
The “divinely sweet oil” - ambrosial oil - would not be solely made from a common herb, but it would not be a stretch to assume that the sweet-smelling fragrance of Aphrodite’s temples and a component of the sweet oil would be the famed perfume herb of her homeland.
In Virgil’s Aeneid 657-694, Aphrodite (Venus) must put Ascanius to sleep so Eros (Cupid) can impersonate him:
But Venus pours gentle sleep over Ascanius’s limbs, and warming him in her breast, carries him, with divine power, to Idalia’s high groves, where soft marjoram smothers him in flowers, and the breath of its sweet shade.
We have to suppose that Virgil deliberately chose Cyprus because of its significance to Aphrodite, and therefore also deliberately named the marjoram on which Ascanius lay because of its significance.
Both Pliny the Elder and Dioscorides, a Greek physician 40-90AD, describe multiple gynaecological uses for marjoram. While Aphrodite is rarely associated with medicine, the link to gynaecology is an interesting nod to her. Referring back to marjoram supposedly carrying the divine scent of Aphrodite, the link to the sexual nature of the goddess becomes obvious, especially when considering the typical placement points for perfumes are also erogenous zones (neck, breast, inner arm and wrist, inner thigh, etc.)
[2] Natural Histories Note 34 and Natural Histories Note 1
[3] Natural Histories Book XIII
Smell and the Ancient Senses by Mark Bradley