Examples of non-seed plants include ferns, mosses, liverworts and hornworts. While many non-seed plants do not have a vascular system, some, such as ferns, are vascular plants. All plants are believed to be descendants of multicellular green algae.
While non-seed plants share the inability to produce seeds, they do have some differences. One example is the comparison of ferns and mosses. As vascular plants, ferns are able to grow tall because they have a vessel system to transport nutrients from the roots up through the stalks. Mosses, lacking this system, remain close to the ground. The sporophytes of ferns grow larger than the gametophytes, which is not the cases of mosses. What is viewed as a fern is actually its sporophyte.