Plant advice?

I have a tank that I feel like it needs more life. I already have some plants in it but I really want more stem plants. I have a handful of Java ferns, a few hornwort and another plant (completely forget its name) and just wanted to add more life to it. I thought of adding a carpet plant in the past but I don’t inject CO2. Any advice? The tank has one betta and is 5 gallons (don’t kill me I know the tank is the minimum for bettas)