A common mother-symbol is the tree of life or wood of life:
The tree of life may have been, in the first instance, a fruit-bearing genealogical tree, and hence a kind of tribal mother
CW5 ¶ 321Numerous myths say that human beings came from trees, and many of them tell how the hero was enclosed in the maternal tree-trunk, like the dead Osiris in the cedar-tree, Adonis in the myrtle, etc. (fig. 023)
CW5 ¶ 321178 CW5 Ser: 3 Par 321 (b) FigNo 023
Numerous female deities were worshipped in tree form, and this led to the cult of sacred groves and trees:
CW5 ¶ 321Juno of Thespiae was a bough
Juno of Samos a plank
Juno of Argos a pillar
The Carian Diana was an unhewn block of wood
Athene of Lindus a polished column
Ceres of Pharos was `a rough and shapeless wooden stake with no face'
Latona at Delos was `an amorphous bit of wood'
Attic Pallas as a `cross-post'
Hence when Attis castrates himself under a pine-tree, he did so because the tree has a maternal significance
CW5 ¶ 321