Originally Venus was worshipped in particular by gardeners and vinedressers as a goddess of Spring who presided over flower-gardens and vines.  She came to be regarded as the mother of the Roman people, and in her honour as such (Genetrix) Caesar and Hadrian erected temples.  The first day of April was a day sacred to her.  Venus sometimes appears of double sex, just as in Sparta sometimes Aphrodite was represented as bearded. (An Encyclopaedia of Religions, Canney, 1921)

    43.  The characteristic attribute of the passive generative power was expressed in symbolical writing, by different enigmatical representations of the most distinctive characteristic of the female sex; such as the shell, or Concha Veneris,¹⁵⁰ the Fig-leaf,¹⁵¹ Barley Corn,¹⁵² or the letter Delta;¹⁵³ all which occur very frequently upon coins, and other ancient monuments in this sense.  The same attribute personified as the goddess of Love or desire, is usually represented distinguished by one of these symbols, and called Venus, Kypris, or Aphrodite, names of rather uncertain etymology.¹⁵⁴  She is said to be the daughter of Jupiter and Dione; that is, of the male and female personifications of the All-pervading Spirit of the Universe; Dione being, as before explained, the female Dis or Zeus, and therefore associated with him in the most ancient oracular temple of Greece at Dodona.¹⁵⁵  No other genealogy appears to have been known in the Homeric times; though a different one is employed to account for the name of Aphrodite in the Theogony attributed to Hesiod.
    ¹⁵⁰ Augustin: The City of God, vi.9.  Clement of Alexandria: Exhortations.  "The Kteis gunakeios (woman's comb), which is, to speak with a euphemism, and in mystic language, the female sexual parts."
    ¹⁵¹ Plutarch: Isis and Osiris, 36.  "They make a figure of a fig-leaf, both for the king and southern climate, which fig-leaf is interpreted to mean the generating and fecundating of the universe, for it seems to have some resemblance to the sexual parts of a man."
    ¹⁵² Eustathius On Homer.  "The barley-corn, denoting the vulva among the writers upon the Bacchic komuses."
    Clement: Exhortations, iii.  "A species of oysters in sympathy with the moon."  There was a notion entertained in ancient times that shell-fish had some secret sympathy or relation with the moon, and hence they were similarly employed as symbols.
    ¹⁵³ Suidas: "Delta, the fourth letter; it also signifies the vulva."
    ¹⁵⁴ The first may be from the verb beinein, Suidas explaining Βεινος or Βινος to be the name of a goddess; and the name Venus only differs from it in a well-known variation of dialect.
    The second may be from κυοπορις, i.e. κνειν πορισκουσα, though the theogonists derive it from the island of Cyprus.  Schol. Ven. on the Iliad, v. 458.  Hesiod: Theogony.
    The third is commonly derived from aphros, the foam of the sea, from which she is fabled to have sprung; but the name is older than the fable, and doubtless received from some other language.  It is perhaps from the Sanskrit, paradesa, a garden or beautiful woman; or from Dis, the masculine of Dione.
    ¹⁵⁵ Strabo: viii. 506.  "In the same temple with Zeus, or Jupiter, was also the simulacrum of Dione." 
(The Symbolical Language of Ancient Art and Mythology: An Inquiry, by Knight, 1892).