I am using captcha in Zend. But When I render captcha element in view, it shows image, an field for enter text and also another field with a string in it. I want hide this text field with a string.

I am creating captcha element like this in Form.php:

$captcha = new Zend_Form_Element_Captcha( 'captcha',  
                      array('label' => "", 
                      'captcha' => array( 
                      'captcha' => 'Image',
                      'name' => 'myCaptcha',  
                      'wordLen' => 5,  
                      'timeout' => 300,  
                      'font' => 'captchaFonts/ACME_ExplosiveBold.ttf',  
                      'imgDir' => 'captchaImages/',  
                      'imgUrl' => '/captchaImages/',  
                     )));

Then render this in view.phtml:

$this->element->captcha

Why it is showing an extra text box on browser with a string and how to hide this?

Thanks.