Green algae
Chlorophytes & Charophytes
The green algae are a paraphyletic grade of algae, which are the ancestors and cousins to the land plants. The green algae (sensu lato) are the most diverse group of algae. During Earth's history, saltwater green algae evolved to survive in freshwater, forming the charophyte lineage. Over time, these freshwater algae radiated to survive in almost every freshwater env't (lakes, ponds, vernal pools, glaciers). Those populations that evolved to survive frequent drying gave rise to the land plants probably during the Cambrian.
Features
Even though the green algae are paraphyletic, they share the same following features:
Autotrophic organisms
Possess chlorophyll a and b
Green algae store energy as starch
Mostly freshwater; some marine & terrestrial
Some have a haplo-diplontic lifecycle, and others are haplontic, and others are diplontic
Geologic Age
Paleoproterozoic - present
Classification
Within Archaeplastida, there is a split between the larger group of green algae called the Chlorophytes and a group of green plants called the Streptophytes, which includes some freshwater green algae as well as land plants
└Viridiplantae (Plants)
Above: Ulva life cycle: sporophyte (lower left) produces spores through meiosis; spores germinate into gametophytes; mature gametophytes produce +/- gametes; gametes are released are fertilize/fuse with each other; Zygote grows into a sporophyte
Additional Reading
Rare Chlorophycean Alga Growth From Human Tissue Sample (MedPageToday 6Mar2015)
Chlorophycean algae maybe some of the longest surviving organisms on Earth, 34 Ka (Lowenstein et al. 2011)