Roots growing upwards

Mike described hid Crypt. wendtii producing thin hair roots upwards out of 
the substrate. I have the same phenomenon with my clump of C. 
retrospiralis. These are fine, branching, green in colour and about 3-4 
inches in length. the plants are healthy as far as I can tell but the 
clumps of C. wendtii and C. nevillii in the same tank are not showing any.

Bruce Hansen.