Structure and function of spores in the aquatic heterosporous fern family Marsileaceae
Abstract
Spores of the aquatic heterosporous fern family Marsileaceae differ markedly from
spores of Salviniaceae, the only other family of heterosporous ferns and sister group
to Marsileaceae, and from spores of all homosporous ferns. The marsileaceous outer
spore wall (perine) is modified above the aperture into a structure, the acrolamella,
and the perine and acrolamella are further modified into a remarkable gelatinous layer
that envelops the spore. Observations with light and scanning electron microscopy
indicate that the three living marsileaceous fern genera (Marsilea, Pilularia, and
Regnellidium) each have distinctive spores, particularly with regard to the perine
and acrolamella. Several spore characters support a division of Marsilea into two
groups. Spore character evolution is discussed in the context of developmental and
possible functional aspects. The gelatinous perine layer acts as a flexible, floating
organ that envelops the spores only for a short time and appears to be an adaptation
of marsileaceous ferns to amphibious habitats. The gelatinous nature of the perine
layer is likely the result of acidic polysaccharide components in the spore wall that
have hydrogel (swelling and shrinking) properties. Megaspores floating at the water/air
interface form a concave meniscus, at the center of which is the gelatinous acrolamella
that encloses a "sperm lake". This meniscus creates a vortex-like effect that serves
as a trap for free-swimming sperm cells, propelling them into the sperm lake.
Type
Journal articleSubject
Science & TechnologyLife Sciences & Biomedicine
Plant Sciences
acrolamella
exine
heterospory
hydrogel
Marsilea
Marsileaceae
perine
Pilularia
Regnellidium
reproductive biology
sperm lake
spore
PLANT
HETEROCHRONY
INNOVATION
SPOROCARPS
MORPHOLOGY
MEGASPORE
PHYLOGENY
SEQUENCES
XYLEM
Permalink
https://hdl.handle.net/10161/21863Published Version (Please cite this version)
10.1086/340736Publication Info
Schneider, H; & Pryer, KM (2002). Structure and function of spores in the aquatic heterosporous fern family Marsileaceae.
International Journal of Plant Sciences, 163(4). pp. 485-505. 10.1086/340736. Retrieved from https://hdl.handle.net/10161/21863.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
Collections
More Info
Show full item recordScholars@Duke
Kathleen M. Pryer
Professor of Biology

Articles written by Duke faculty are made available through the campus open access policy. For more information see: Duke Open Access Policy
Rights for Collection: Scholarly Articles
Works are deposited here by their authors, and represent their research and opinions, not that of Duke University. Some materials and descriptions may include offensive content. More info