The invention provides seed and plants of the lettuce line designated RS 16890990. The invention thus relates to the plants, seeds and tissue cultures of lettuce line RS 16890990, and to methods for producing a lettuce plant produced by crossing a plant of lettuce line RS 16890990 with itself or with another lettuce plant, such as a plant of another line. The invention further relates to seeds and plants produced by such crossing. The invention further relates to parts of a plant of lettuce line RS 16890990, including the gametes of such plants.