Roots: Approximately 1/3 of a plant's biomass is invested in roots... this proportion may vary widely however approaching close to 2/3 in grasses of the plains and down to negligible fraction in epiphytes which reside on trees. Primary functions of roots include:

1. anchorage; critical role especially where climate may be severe-- windy, frost-heaving areas, where soils are difficult to hold onto ( i.e. sandy or aquatic areas)

2. water and mineral absorption:

• partially but not totally a passive process- in some cases plants will invest energy into excluding toxic substances ( salts,toxins)
• absorption may be aided through mycorrhizal associations, which we investigate later

3. storage- critical reserves of food especially for perennials ( trees [ 2-3 years worth]; grasses, biennials which overwinter)

4. production of various chemicals involved in growth ( hormones) and defense ( competition, antimicrobial)

5. transport of materials up, down, and laterally.. Conduction-Roots transport water and dissolved nutrients to and from the shoot. The roots of plants even transport carbon dioxide for photosynthesis. The leaves of these plants usually have thick cuticles and lack stomata. Ê

Natural grafting: Some question the individuality of root systems: recent studies indicate that tree roots fuse between individuals, with storage products as well as microbes transmitted from one to a another; this may be regulated via the mycorrhizal associations.