A phyloGENETIC tree is not the same thing as a taxonomic tree, which is what Cal described. rRNA and molecular studies are used in phylogenetics to determine relations between species.
1 As the light intensity increases, the rate of photosynthesis increases. 2  However, the rate will not increase beyond a certain level of light intensity. 3  At high light intensities the rate becomes constant, even with further increases in light intensity, there are no increases in the rate.
Grow lights should provide the proper spectrums of light for photosynthesis which is the key to plant growth. Violet-blue light offers a light in the 400 - 520 nanometer range that encourages chlorophyll absorption, photosynthesis and growth.