Who is Tia Ignacia from Tortilla Flat and what is their importance?

Tia Ignacia is the a 45-year-old widow who lives on the edge of Tortilla Flat. When she invites Big Joe Portagee in from the rain, she offers him a glass of wine, and by his his fourth glass he begins to relax. As they sit by the fire, Tia Ignacia inspects Joe and tries to get him to take off his coat to dry. Joe, however, is too busy concentrating on the wine to notice she is interested. When Joe falls asleep.... Tia Ignacia is incensed. The two later make love in the road.