I don't think asparagus is considered a "leafy green" as such (might be wrong) - but it has a bit of iron and copper in it, as well as possessing a reasonable percentage of protein per gram.
Raw asparagus blends quite well - I do chop it up into smaller sections (perhaps 3cm to 5cm in length), as I've only got a cheap $30 blender :)
In terms of taste and texture - for me, it took a bit of getting used to (it tastes similar but not identical to cooked), but I like it now.
I think a banana/date/kale smoothie is wonderful; I go for 8 dates, 6 bananas and 2-3 cups kale, but I'm trying to up the kale as I get used to it!!