Get fields of sobject in picklist of visualforce

 //Apex class  
 public string fields{set;get;}  
 Map<String, Schema.SObjectType> gd = Schema.getGlobalDescribe();  
 //method for fields retrival and storage in picklist  
 public list<selectoption> getFields(){  
   String type='Account';  
   List<SelectOption> options = new List<SelectOption>();  
    //Creating sObject for dynamic selected object  
       Schema.SObjectType systemObjectType = gd.get(type);  
       //Fetching field results  
       Schema.DescribeSObjectResult r = systemObjectType.getDescribe();  
        Map<String, Schema.SObjectField> M = r.fields.getMap();  
       //Code for picklist of fields in  
       options.add(new SelectOption('None' ,'--None--')) ;  
       for(Schema.SObjectField fieldAPI : M.values()){  
       options.add(new SelectOption(fieldAPI.getDescribe().getName() ,       fieldAPI.getDescribe().getLabel())) ;  
       }  
       return options;  
     }//end of code for retrieving fields dynamically  

//vf page

 
  <apex:selectList value="{!Field}" size="1">  
    <apex:selectOptions value="{!Fields}">  
    </apex:selectOptions>  
  </apex:selectList>