Sort Plant Groups by Flagella, Vascular Tissue and Water Dependence

Green algae (Chlorophyta) have chlorophyll a and b and a cellulose wall, and their motile cells usually have two to eight equal flagella. Brown algae (Phaeophyta) contain fucoxanthin and have two unequal lateral flagella on their motile cells. Red algae (Rhodophyta) have phycoerythrin and no flagellated stages at all. Cyanophyta (blue-green algae) are prokaryotic cyanobacteria with no flagella. So of these groups, those characterised by two flagella are the brown and the green algae.

Bryophytes lack true roots, stems and leaves (they have rhizoids and root-like, stem-like and leaf-like structures), they have no xylem or phloem, and their male gametes are motile and need water to swim to the egg, so they depend on water for completing the life cycle. Pteridophytes are the first vascular plants, with xylem and phloem. The stem of Equisetum is the classic example with carinal canals (within the vascular bundles under the ridges) and vallecular canals (in the cortex under the furrows). Lycopodium is a club moss; Magnolia and Gnetum are seed plants.

Truly aquatic or floating forms include the algae Spirogyra, Ulothrix, Cladophora, Chlorella, Cosmarium and Chara, the floating ferns Azolla and Salvinia, and the aquatic liverworts Riccia fluitans and Ricciocarpus natans. Marchantia and Funaria (a moss) grow on damp soil and rocks, while Lycopodium and Gnetum are terrestrial, so these are not pond organisms.

A hemiparasite has green leaves or stems and photosynthesises, but taps the host for water and minerals: the mistletoe Dendrophthoe falcata, the most common mistletoe in India, is a stem hemiparasite growing on the branches of trees. Holoparasites such as Cuscuta (dodder) and Orobanche have no chlorophyll and depend wholly on the host, and Monotropa is mycoheterotrophic, depending on fungi.