Answer to Question 1
Believe it or not, the critical first set in identifying turf weeds is to establish which
species in the landscape is the desired turf. Oftentimes, turf species in the wrong setting are the most troublesome weeds. Any remaining plants that detract from the desired turf quality should be managed as weeds. The second step in the process is to determine if the plant is a broadleaf or a grass. At this point many different approaches can be followed. For commonly observed species you could simply match the unknown species with an illustration in the text for the season of observation. For more difficult species you should consult the appropriate key.
Answer to Question 2
One of the greatest influences that weeds exert on turf is direct competition. This competition is generally for water, light, nutrients, and space. The competition is particularly strong under conditions that do not favor turf growth. This might be a situation of high or low pH, high or low moisture levels, or other stresses. High levels of moisture and nitrogen encourage germination and rapid growth of annual bluegrass at a rate greater than the desired turf. Soils with a low pH allow rapid development of plants like red sorrel while compacted soils slow turf growth allowing species such as knotweed and crabgrass to flourish.
A detailed look at the steps of the citric acid cycle
Steps of Infection via Viruses
Édouard Manet, Le Déjeuner sur l'herbe (Luncheon on the Grass).
A step stool can be used to assess the ability to use steps.
The steps of wound repair.
Frederick Griffith’s experiment identifying a ″transformation factor″ responsible for heredity