I think this is a spider in the Family Tetragnathidae, much like the Venusta Orchard spider, but this one is much bigger than those, and much bigger than the common long-jawed orbweaver: http://www.cirrusimage.com/spider_longjawed_orb_weaver.htm. Can anyone ID this species? I would assume this is a female. I saw no males who presumably are much smaller.

These spiders (there were several, but all these pictures are the same individual) were hunting in plants along the shore of a river. They had "lifeline" type webs all over the place, but only for easily moving amongst the foliage; they were not trapping prey as much as wandering around striking that pose they make imitating thorns. I did not see them capture anything. More, larger images at Tetragnatha elongata