Judy Horton, communications manager for Yates Australia and author of a monthly garden calendar on the website, has found a reference to the pea-bean in Growing Peas & Beans by Australian botanist David R Murray (Kangaroo Press, 1999).
She has kindly scanned the relevant text and sent a copy.
“The name ‘pea bean’ is just as unfortunate [as ‘sweet pea’]. Some people take the term literally and actually believe that such seeds represent a cross between a pea and a bean. For instance, Weaver (1997) proposes that a pea bean still sold as such in the USA is a ‘very old cross between the white marrow pea and the red cranberry pole bean’. Peas and beans are so different, however, that any attempted cross would not give viable offspring. All that the term is meant to impart is that a bean has taken on a rounder or globose shape, resembling that of a pea. Alternatively, it may refer to a pea with an unusual mottled seedcoat pattern, resembling that of some beans. To avoid confusion, it is a term best avoided.”
I don’t think we can naysay the findings of a botanist so our hunt for the pea-bean, while fun and with some interesting twists and turns, has been a wild goose chase.