Lycopodium clavatum (running clubmoss) - Lycopodiaceae. An example of a seedless vascular plant - so reproduces by spore similar to liverworts but also has true conductive tissues, xylem and phloem. Unlike the liverworts, club mosses are homosporous (have only one kind of spore) and spores give rise to bisexual gametophytes. 
The above ground portion pictured rather blurrily above is the rhizome. The gametophytes of some club mosses, including this species, grow below ground, are non-photosynthetic and maintain a mycorrhizal relationship with fungi. Strobili are borne on aerial stems attached to the rhizomes (pictured at left). Strobilus (pl. strobili) = a cone-like cluster of sporophylls on an axis. Sporangium borne on the strobili release spores that develop into the gametophyte which bear both archegonia and antheridia. During fertilization, biflagellated sperm produced by the antheridium swim to the egg produced by the archegonium (the presence of water is required). The newly produced sporophyte may remain attached to the gametophyte for a long time but eventually detaches to become a separate individual. (Plant Biology - Raven, Evert, Eichhorn)
