Ferns (Pteridophytes) There are several methods that can be applied to pteridophyte cryopreservation. Spores, if available, can be dried and cryopreserved (e.g. Ballesteros et al., 2011). If only a few spores are available, they can be germinated into gametophytes, which can be multiplied in vitro and the gametophytes can be cryopreserved (e.g. Pence, 2000). Finally, if in vitro cultures of the sporophytes are available, these may be cryopreserved most easily by culturing to develop green globular bodies, which can then be cryopreserved (e.g. Pence, 2015). Expand for Selected References Ballesteros D, Estrelles E, Walters C, Ibars AM (2011) Effect of storage temperature on green spore longevity for the ferns Equisetum ramosissimum and Osmunda regalis. Cryo-Letters 32:89–98. Ballesteros D, Estrelles E, Walters C, Ibars AM (2012) Effects of temperature and desiccation on ex situ conservation of nongreen fern spores. 1. Am J Bot 99:721–729. doi: 10.3732/ajb.1100257 Li Y, Shi L (2015) Effect of maturity level and desiccation process on liquid nitrogen storage of green spores of Osmunda japonica. Plant Cell Tissue Organ Cult 120:531–538. doi: 10.1007/s11240-014-0619-9 Makowski D, Rybczyński JJ, MikuLa A, Klimaszewska K (2015) A simple way to overcome the recalcitrance of the water fern Ceratopteris thalictroides (L.) Brongn. to cryopreservation. Acta Soc Bot Pol 84:385–388. doi: 10.5586/asbp.2015.032 Mikuła A, Jata K, Rybczynski JJ (2009) Cryopreservation strategies for Cyathea australis (R. Br.) Domin. Cryo-Letters 30:429–439. Mikula A, Makowski D, Walters C, Rybczynski JJ (2010) Exploration of cryo-methods to preserve tree and herbaceous fern gametophytes. In: Fernández H, Kumar A, Revilla MA (eds) Working with Ferns: Issues and Applications. pp 173–192 Pence VC (2018) Growth of fern gametophytes after 20 years of storage in liquid nitrogen. Fern Gaz 20:337–346. Pence VC (2014) In vitro propagation and cryopreservation of the endangered filmy fern, Trichomanes punctatum subsp. floridanum (Hymenophyllaceae). Fern Gaz 19:307–317. Pence VC (2001) Cryopreservation of shoot tips of Selaginella uncinata. Am Fern J 91:37–40. Pence VC (2015) Propagation and cryopreservation of Asplenium scolopendrium var. americanum, the American hart’s-tongue fern. Am Fern J 105:211–225. Pence VC (2000) Cryopreservation of in vitro grown fern gametophytes. Am Fern J 90:16–23. Wilkinson T (2002) In vitro techniques for the conservation of Hymenophyllum tunbrigense (L.) Sm. Fern Gaz 16:458.