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seed fern

noun
1.
any of various plants of the order Lyginopteridales (or Cycadofilicales), known only as fossils, having fernlike leaves and reproducing by means of seeds.
Also called pteridosperm.
Origin
1925-1930
1925-30
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for seed fern

seed fern

noun
1.
another name for pteridosperm
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Encyclopedia Article for seed fern

pteridosperm

loose confederation of seed plants from the Carboniferous and Permian periods (about 360 to 250 million years ago). Some, such as Medullosa, grew as upright, unbranched woody trunks topped with a crown of large fernlike fronds; others, such as Callistophyton, were woody vines. All had fernlike foliage; however, they reproduced by seeds, with ovules and pollen organs attached to the fronds. Gamete-producing structures in the seeds were surrounded by a hard inner integument and a fleshy outer layer. These features have led some authorities to speculate that these seeds may have been dispersed by animals. Some seeds were large. (Pachytesta gigantea, a seed of Medullosa, grew up to 7 cm [2.7 inches] long.) Pollen organs of seed ferns were also large and complex and were commonly made up of many pollen sacs fused into a large structure. Some authorities suggest that these large structures and the large pollen grains they contained were evidence of pollination by animals

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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