I want a GameObject to keep looking at player, but remaining upright

I want a blade of grass to keep looking at the player, but so that it’ll remain upright.
I’ve searched everywhere, but all I found is help with rigibodies. It isn’t a rigidbody.

This is what I have so far (CSharp):

using UnityEngine;
using System.Collections;

public class muru_vaatamine : MonoBehaviour {

	GameObject player;

	void Start ()
	{
		player = GameObject.FindWithTag ("Player");
	}

	void Update ()
	{
		transform.LookAt (player.transform);
	}
}

Try this:

void Update ()
{
    Vector3.pos = player.transform;
    pos.y = transform.y;
    transform.LookAt (pos);
}