• canopy layer (only for larger gardens, not on roofs, balconies, etc.)
• low tree layer
• shrub layer
• herbaceous layer
• rhizosphere
• soil surface (ground cover)
• vertical layer (climbers and vines)

• nitrogen
• nutrients/ dynamic accumulators (non mineral, mineral, soil)
• mulch
• pollination
• protection from external threats

• introduction on gardening with plant guilds: http://members.optusnet.com.au/~rnbnielsen/hort%20course%20nscf/Course%20Resources/Guild%20theory.htm
• on working with plant guilds in permaculture: http://www.self-willed-land.org.uk/permaculture/plant_guilds.htm
• plant & funghi in food forests: http://www.permaearth.org/foodforestarticle.html
• Permaculture Guilds: A Primer: http://onestraw.blogspot.com/2007/03/permaculture-guilds-primer.html
• permaculture institute: Permaculture Food Forest: http://www.permaculture.org/nm/index.php/site/Permaculture-Food-Forest/
• Dynamic accumulators depending on the soil type:
  • http://en.wikibooks.org/wiki/Permaculture_design/Soil#Dynamic_Accumulators_of_Nutrients_for_Composting
  • http://hubpages.com/hub/Dynamic-Accumulators-for-Better-Soil
• what's important in creating a linear guild: http://www.self-willed-land.org.uk/permaculture/plant_guilds.htm
• what do plants consider nutrition: http://en.wikipedia.org/wiki/Plant_nutrition
• plant guilds: http://www.eco-sf.org/resources/fact-sheets/11-edible-and-medicinal-native-plant-guilds

See also edible_guilds, roof guilds, aronia guild