I love to mix green and wax beans. My DH isn't terribly fond of wax beans, however, this year I planted Dragon Tongue Beans (they are yellow with purple "stripes" that represent, I guess, a dragon's tongue...). Anyway, these plants have done very will re: surviving the heat, being disease resistant (surprise, since they are an heirloom type). Yesterday we picked about 9 cups of them. First observation, they are very tender. You can eat even the larger ones raw (they all grow under while there are still blossoms on the tops of the plants--I hadn't been checking under and I hadn't checked for about 4 days because of my deadlines). Second observation, they don't have a "fuzzy" texture when raw. Third observation, they are flat, not round (you can also use them for dried beans if you leave them for about 100 days). Last, they don't get "slimey" when steamed.
We snapped them (they snap very nicely--DH said that they were more watery than the green bush or purple bush beans when he was snacking on the raw ones--and they had a nice, fresh flavor). We steamed them for about 5-6 minutes--I don't like my fresh beans overcooked. The purple "tongues" disappear (that disappinted me, but maybe blanched for a cold bean salad they'd stay--like purple bush beans will retain their color if blanched and put in ice water). Nice flavor, nice texture--definitely I'm going to add these to my bean varieties in the years to come. I still have to see how they freeze, but that was the first round. I have another couple of rows that will be ready in 2 weeks (the season is behind). Oh, another thing, the yield was respectable. Sometimes with the heirloom varities you get lower yield. My DH was surprised because that has been his comment in the past about heirloom varieities.
Here's a link that shows what they look like. We had burgers on the grill, swiss chard sauteing, and were busy snapping beans. I didn't have time to snap a picture.