The sunflowers that Allen had granted sentience weren't different in appearance from the average sunflower. It doesn't even have a mouth or face on it but it can remove itself from the ground and use its roots as its feet for mobility.
Not only could it absorb the sunlight in its surroundings to perform an attack, but it could also use the sunlight to strengthen itself. Since it possessed sentience, it was to be expected that it was similar to the plants in cultivation worlds which could use spiritual qi to cultivate themselves and achieve human form.
But instead of using spiritual qi to increase its cultivation base or power level, Allen's sunflower would use sunlight to strengthen itself and increase its power level until it could achieve human form.
