The Kingdom Plantae represents an extremely large group of mostly terrestrial organisms that are photosynthetic.
Hence they provide the base of the food chain for most terrestrial ecosystems. Members of this group have ancestral ties to the Chlorophyta (Green Algae), and like them, plants have chlorophylls a and b, carotenoids, store food as starch, and have cellulose cell walls. Many features of plants are the result of adaptations to life on land, such as: 1) a protective jacket of cells surrounding egg- and sperm-producing structures (the archegonia and antheridia, respectively), a protective layer of cells covering the spore-producing structures (sporangia), 3) a protected embryo, and 4) specialized cells for water conduction. However, members of many plant groups have secondarily readapted to living in aquatic
Big thanks to https://www.msu.edu/course/lbs/158h/manual/Plantae.pdf.