Nikolai Mavrenkov already created a good description of the problem on Stack Overflow: http://stackoverflow.com/questions/36893449/textarea-placeholder-isnt-shown-in-ie-11-being-rendered-using-react

I just can confirm it breaks in IE11, but works in IE10 (and other browsers) with React v15.0.2.

var ReactDOMTextarea = {
  getHostProps: function(inst, props) {
    invariant(
      props.dangerouslySetInnerHTML == null,
      '`dangerouslySetInnerHTML` does not make sense on <textarea>.'
    );
    
    
    
    
    
    var hostProps = Object.assign({}, props, {
      value: undefined,
      defaultValue: undefined,
      children: '' + inst._wrapperState.initialValue,
      onChange: inst._wrapperState.onChange,
    });
    return hostProps;
  },
  mountWrapper: function(inst, props) {
    if (__DEV__) {
      ReactControlledValuePropTypes.checkPropTypes(
        'textarea',
        props,
        inst._currentElement._owner
      );
      if (
        props.value !== undefined &&
        props.defaultValue !== undefined &&
        !didWarnValDefaultVal