Land plants and closely-related green algae (charophytes) are
classified as Streptophytes; the remaining green algae are
chlorophytes.
LEARNING OBJECTIVE [ edit ]
Discuss the general similarities of green algae and land plants
KEY POINTS [ edit ]
There is a diverse array of green algae including single-celled or multicellular species, which can
reproduce both sexually or asexually.
The classification of green algae is challenging because they bear many of the structural and
biochemical traits of plants.
Species of green algae that are closely related to embryophytesare classified as charophytes while
the remaining green algae are classified as chlorophytes.
Like plants, charophytes have chlorophyll a and b, storecarbohydrates as starch, have cell walls
consisting of cellulose, and undergo similar cell-division processes.
Charophytes have unique reproductive organs that differ considerably from that of other algae.
TERMS [ edit ]
streptophytes
a subphylum consisting of several orders of green algae and embryophytes
Chlorophyta
a division of green algae that are considered more distantly related to plants
Charophyta
a division of green algae that includes the closest relatives of the embryophyte plants
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Streptophytes
Until recently, all photosynthetic
eukaryotes were considered members of
the kingdom Plantae. The brown, red, and
gold algae, however, have been reassigned
to the Protista kingdom. This is because,
apart from their ability to capture
light energyand fix CO2, they lack many
structural and biochemical traits that
distinguish plants from protists. The
position of green algae is more ambiguous.
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Green algae include unicellular and colonial flagellates, most with two flagella per cell, as well
as various colonial, coccoid, and filamentous forms, along with macroscopic seaweeds, all of
which add to the ambiguity of green algae classification since plants are multicellular.
Green algae contain the same carotenoids and chlorophyll a and b as land plants, whereas
other algae have different accessory pigments and types of chlorophyll molecules in addition
to chlorophyll a. Both green algae and land plants also store carbohydrates as starch. Cells in
green algae divide along cell plates called phragmoplasts and their cell walls are layered with
cellulose in the same manner as the cell walls of embryophytes. Consequently, land plants
(embryophytes) and closely-related green algae (Charophyta) are now part of a
new monophyleticgroup called Streptophyta. The remaining green algae, which are more
distantly related to plants, belong to a group calledChlorophyta that includes more than 7000
different species that live in fresh or brackish water, in seawater, or in snow patches.
The Charophyta are a division of green algae that includes the closest relatives of the
embryophyte plants . Charophyta are a small but important group of plants which show
marked differences from both the Thallophyta and the Bryophyta. They are all specialized
water plants. The reproductive organs consist of antheridia and oogonia, although the
structure of these organs differs considerably from the corresponding organs in the Algae. Chara vulgaris
A representative charophyte alga is Chara vulgris, or common stonewort, which is a multicellular
branching species that can grow up to 120m long.