ok… i am introducing this new word…
phototropism
Phototropism or heliotropism are botanical terms for an organism response to light.
if the growth movement is toward light, so it is called “negative phototropism”.
quoted from wikipedia
i found this interesting scene happened on the Choy Sum on the floor in my kitchen. it stands right up straight and growing taller and taller day by day, as i have a ceiling light on on the ceiling. but, there is no water, i wonder how it is going to stay alive…?

day 1…

day 2…

day 3…
i wonder if i keep this so called experiment going, when can i eat the choy sum…? but probably after days, i will have MORE choy sum to eat… *grinz*
[additional]
ok, since some people like n305er dont know what is Choy Sum… and here goes the definition…
Choy sum (choi sum) (Brassica rapa var. parachinensis or Brassica chinensis var. parachinensis) is sometimes referred to as a flowering pak choy or Chinese flowering cabbage.
quoted from Queensland Government, click for more info about Choy Sum…
also thanks Louyeh for the help of finding the above site.