Lettuce 'Gustav's Salad' / 'Dad's Salad'

This tender, melting butterhead lettuce is a true Dutch variety, grown by an enthusiast for its delicious taste and texture.
The story of 'Gustav's Salad'. Gustav was a resident of one of the islands (Zeeland?) who had developed his own kind of 'melt-in-your-mouth' butterhead lettuce. He cycled through the entire village, a bucket full of lettuce heads dangling from his handlebars, delivering them to countless tables in the village. Each year, he allowed a portion of his lettuce to mature to produce seeds for the following year, enabling him to grow more of his own flavorful lettuce. Gustav continued to grow lettuce, known locally as 'Dad's Lettuce'. We don't know the origin beyond this, who knows more?

Names:
Latin: Lactuca sativa var. capitata
Dutch: Kropsla
Also known as: Sla van Pa
English: Butterhead Lettuce