My Wellingtons
Squelching and squelching through the beautiful red.
This is my property.
Two times a day
I pace it, sniffing
The barbarous holly with its viridian
Scallops, pure iron,
And the wall of the old corpses.
I love them.
I love them like history.
The apples are golden,
Imagine it ---
My seventy trees
Holding their gold-ruddy balls
In a thick gray death-soup,
Their million
There are multiple symbolic meanings to  seventy , but a possible application is that of an evolutionary cycle. Is Plath suggesting her life is reaching its conclusion? It also is said to symbolise universality.
Letter in November