Runner beans do, Half runners are regular beans (P. vulgaris

Half-runners are Phaseolus vulgaris, or common bush beans that get bigger than other bush beans and send out tendrils. It's as if half-runners are incompletely dwarfed from pole to bush habit.

Runner beans are another species, Phaseolus coccineus

To more directly answer your question, you may have heard that runner beans, not half runners, emerge with the first true leaves, leaving the seed halves, or cotyledons, underground. This is true of Phaseolus coccineus.

Half runners, however, are Phaseolus vulgaris and will emerge the cotyledons first. So even if the cotyledons came up, you may have half runners. Plan for a big bush that will send up tendrils to 3 feet long. You can try to train them on a short trellis if you want.

ok, thanks for the info. So I guess they will cross with other bush beans but will they cross with pole beans?

Technically, they will cross with any P. vulgaris. In real time, P.vulgaris is pretty self contained and cross pollination is very low.

The original wild state for P vulgaris is a pole habit. Bush beans are dwarfed P. vulgaris, developed for mechanical harvesting. Dwarfed or bush runner beans, P. coccineus, have also been developed.

"Runner" bean does not mean pole, it is a European name applied to P. coccineus.

Like Farmerdill said, P. vulgaris are unlikely to cross much. P. coccineus are said to be more likely to cross with one another, which is why I am hesitant to grow more than one runner bean per year.

"...it is a European name applied to P. coccineus."

Just a small point. 'Runner bean' is just the British name. All the multitudinous languages of Europe have their own names in their own languages.