I refer the honourable gentleman to my post in which I have now highlighted his own turn of phrase:
We have a frog, or perhaps a toad, called Spinach (for obvious reasons). Perhaps you would like to meet him!
And our remaining tadpole is called Seaman
Ahhh, Mr Toad!
This, one assumes, is the origin of a certain Mr Toad - and I can't see any obvious reason to call it/him/her Spinach! If it is due to the fact of the colour, then you could equally have called it: Spring Greens, Cabbage, Brussels Sprout, Lettuce, Brocolli or indeed, any other green vegetable.