Based on the descriptions provided, Horatio likely found a seedless vascular plant because it grows near water. Seedless vascular plants, like ferns, often thrive in moist environments, typically near streams or other bodies of water. They have vascular tissues, which allow for the transport of water and nutrients, but do not produce seeds. If the plant lacks stems specifically, it may be more indicative of certain types of seedless vascular plants. Thus, the most suitable choice is:
seedless vascular because it grows near water.