It is hard to find anything boring in reproduction. Biology is inherently exciting (to me), while reproduction is an extreme - it is regularly re-inventing itself, and like a flea market, there is literally something for everyone! I do not go to flea markets to buy anything (or at least that is my intention); rather, I go to see a cross section of people, a historical perspective of life, and the diversity of everything! In just one aisle, I can find a box of single-play 45s, some LPs (with well-worn card board covers), 8-track tapes, tape cassettes, CDs, Walkmans, iPods … the evolution and diversity of music playback in front of me! Need a chair? There are likely hundreds of different kinds to choose from, ranging from ornamental to artistic to multipurpose. And you can often choose from a variety of different materials. But most importantly, they are all functional. Wouldn't it be fun to go to a Reproduction Flea Market? All the animals and plants would be there hawking their reproduction wares … some used, some less-so, but all functional. I would likely not make it past the first aisle, where the sperm are displayed. Sperm with hooked or smooth heads and a complimenting tail - it is, after all, a classic design for lots of animals (especially mammals). You will also find tailed sperm with cigar-shaped heads (frogs) or triangular heads (sea urchin). But lots of the tables have something different to offer: Sperm with no tails (nematodes), two tails (Turbellarians), or lots of tails (fern)! Fern sperm capture my attention on this particular visit - the alliteration flows so well, and hey, they really are different. Ferns are vascular plants (remember xylem and phloem) with stems, leaves, and roots. The large, feathery, classically shaped structure that we are accustomed to seeing is the sporophyte - the diploid stage that we see in the woods and in lots of moist environments. This stage of its life cycle makes haploid spores that disperse in the wind. Those spores represent the alternative life state - the gametophyte that makes the eggs and the sperm. Yup - ferns are very sexual. In many ferns, the gametophyte stage is small, heart-shaped, and free living. It makes both sperm-forming organs (the antheridium) and egg-producing organs (the archegonium) - functionally akin to animal “gonads”. But here is the extra-cool part: Unlike other angiosperms, which rely on pollen tube growth through the style, fern sperm must swim through water (dew and such) in order to get to the eggs. If the sperm successfully reach the egg, fertilization may occur, returning the organism to a diploid state (joining of the haploid egg and sperm) and hence restarting the sporophytic stage. The number of motility organs in sperm of terrestrial plants varies remarkably. Sperm of liverwort have two tails; of horsetail and ginko sperm have many cilia; of fern have dozens; and of cycads (which looks like a cross between a fern and a tree) have an estimated 20,000 cilia! Many of these plants lack centrioles (as do most flowering plants) in most of their sporophytic cells, but during sperm formation, the centrosomes that form de novo with the cilia and flagella develop hundreds of centrioles! Talk about a gold-mine find at the flea market! With the growth of remarkable technologies that now make any organism tractable, these gems of nature will make the difference between the often-crowded aisles of a research supermarket, with its limited-but-popular selections, to the stimulating aisles of the Biodiverse Flea Market. I love the flea market - Hope to see you there! Y. Mineyuki (2007). J. Plant Res 120:45–51. Gary M. Wessel