I got to thinking about it and did try several different searches on information about the daylilies with very narrow leaves, I found nothing except the very general statement that "daylilies have very narrow grass like leaves) but we know some are much more narrow and grass like than others(but then some grasses have pretty broad leaves). When I do a search and find no information, often that indicates that I am a little crazy and nobody but me is interested in the subject.
But being two other people have posted here I know that is not totally true. However, I can't help but believe if there were a direct correlation with performance in heat and the width of the leaves surely it would be noted somewhere already. So I feel I just have not typed in the correct terms yet to pull up the correct info. The hybridizers must have taken leaf width into consideration at some point and to some degree if it is an actual factor in hot weather performance, I would think.
I will keep looking, if anyone out there finds any info please post it here.
I was looking at the AHS page and found that "foliage habit": evergreen, semi-evergreen, or dormant actually refers to the winter behavior of the foliage, but the page stated that cold hardiness is not determined by foliage habit. I keep reading that but keep seeing that most of use do use foliage habit as a gauge of cold tolerance and heat tolerance. The summer behavior of daylilies on the site seems to have been just skipped over.
I saw no mention of the width of the leaves of daylilies being any kind of indicator.
