Wicked cool article detailing how photosynthethis works here absorbing photons of differing wavelengths to convert CO2 and water into sugars, and how it might function under the light of alien stars.

"...plants on both F- and K-star planets could have colors just like those on Earth but with subtle variations. For F stars, the flood of energetic blue photons is so intense that plants might need to reflect it using a screening pigment similar to anthocyanin, giving them a blue tint. Alternatively, plants might need to harvest only the blue, discarding the lower-quality green through red light. That would produce a distinctive blue edge in the spectrum of reflected light, which would stand out to telescope observers.

The range of M-star temperatures makes possible a very wide variation in alien plant colors. A planet around a quiescent M star would receive about half the energy that Earth receives from our sun. Although that is plenty for living things to harvest—about 60 times more than the minimum needed for shade-adapted Earth plants—most of the photons are near-infrared. Evolution might favor a greater variety of photosynthetic pigments to pick out the full range of visible and infrared light. With little light reflected, plants might even look black to our eyes.

The experience of life on Earth indicates that early ocean photosynthesizers on planets around F, G and K stars could survive the initial oxygen-free atmosphere and develop the oxygenic photosynthesis that would lead ultimately to land plants. For M stars, the situation is trickier. We calculated a “sweet spot” about nine meters underwater where early photosynthesizers could both survive UV flares and still have enough light to be productive. Although we might not see them through telescopes, these organisms could set the stage for life at the planet’s surface. On worlds around M stars, land plants that exploited a wider range of colors would be nearly as productive as plants on Earth."

Those pesky UV bright flares from M stars blast the crap outa planets circling in theie very narror HZs.