Abstract
We investigated the different processes involved in spore liberation in the polypod fern Adiantum peruvianum (Pteridaceae). Sporangia are being produced on the undersides of so-called false indusia, which are situated at the abaxial surface of the pinnule margins, and become exposed by a desiccation-induced movement of these pinnule flaps. The complex folding kinematics and functional morphology of false indusia are being described, and we discuss scenarios of movement initiation and passive hydraulic actuation of these structures. High-speed cinematography allowed for analyses of fast sporangium motion and for tracking ejected spores. Separation and liberation of spores from the sporangia are induced by relaxation of the annulus (the ‘throwing arm’ of the sporangium catapult) and conservation of momentum generated during this process, which leads to sporangium bouncing. The ultra-lightweight spores travel through air with a maximum velocity of ~5 m s-1, and a launch acceleration of ~6300g is measured. In some cases, the whole sporangium, or parts of it, together with contained spores break away from the false indusium and are shed as a whole. Also, spores can stick together and form spore clumps. Both findings are discussed in the context of wind dispersal.
Highlights
Polypod ferns, i.e. members of Polypodiales, comprise about 80% of all extant fern species and constitute an important vascular plant group [1,2]
We investigated the spore liberation in cultivated terrestrial Adiantum peruvianum KLOTZSCH (Pteridaceae), commonly known as the Silver-Dollar or Peruvian Maidenhair Fern, which originates from South America (Ecuador to Peru)
False indusia and sporangia were analyzed with an Olympus BX61 light microscope (Olympus Corp., Tokyo, Japan) equipped with a DP71 digital camera or with Olympus SZX7 or SZX9 stereo microscopes equipped with an Altra20 or a ColorView II camera
Summary
I.e. members of Polypodiales, comprise about 80% of all extant fern species and constitute an important vascular plant group [1,2]. Each specimen produces millions of airborne spores during its life-time [3,4,5]. Their dissemination is essential for population maintenance, gene flow (migration to another population), and for colonization of new habitats [6]. Spores are reported to have a high migrational ability and to achieve long distance dispersal even between continents and oceanic islands and to withstand hostile environmental conditions during transport [7,8,9]. We investigated the spore liberation in cultivated terrestrial Adiantum peruvianum KLOTZSCH (Pteridaceae), commonly known as the Silver-Dollar or Peruvian Maidenhair Fern, which originates from South America (Ecuador to Peru). A. peruvianum grows in PLOS ONE | DOI:10.1371/journal.pone.0138495 October 7, 2015
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
