Sanitation is important for disease, insect, and weed control in greenhouses.
Longstalked phyllanthus. Notice the flowers at the leaflet axils (labeled A).
Liverwort in trays. A gemma cup (circled and marked as A) is the asexual means of propagation.
Flowering woodsorrel. Seeds can shoot 12 feet.
Dodder. The parasitic vine (circled and labeled A) and the flowers (circled and labeled B) of the plant.
Hairy bittercress fruits (labeled A) and flowers (labeled B). All pictures were copied from the following website: http://pubs.caes.uga.edu/caespubs/pubcd/B1246.htm
Tag Archives: woodsorrel
Weed Hotline Issue 19
White clover, an indicator of low mowing height and low fertility soil.
Spurge, an indicator of compacted soil.
Prostrate knotweed, an indicator of compaction.
Red Sorrel, an indicator of low pH, low fertility soil or dry soil.
Plantain, an indicator of low fertility soil.
Nutsedge and Oxalis (woodsorrel), indicators of wet soil.
Nimblewill, an indicator of excess shade.
Goosegrass, an indicator of compacted soil.
Crabgrass, an indicator of low mower height, wet soils, or high fertility. 
Carpetweed, an indicator of dry soil.
Black Medic, an indicator of dry soil. 
Bermudagrass (wiregrass), an indicator of low mowing height, compaction, or high fertility.
All Weed Pictures by Gordon Johnson, Extension Agent, Agriculture and Commercial Horticulture, University of Delaware, Kent County