pteridosperm


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Related to pteridosperm: seed fern

pteridosperm

(ˈtɛrɪdəˌspɜːm)
n
1. (Plants) any extinct seed-producing fernlike plant of the group Pteridospermae. Also called: seed fern
2. (Palaeontology) any extinct seed-producing fernlike plant of the group Pteridospermae. Also called: seed fern
[C19: from Greek pteris a fern + -sperm]

seed′ fern`


n.
any of various fossil plants of the order Lyginopteridales (or Cycadofilicales) that had fernlike leaves and reproduced by means of seeds. Also called pteridosperm.
[1925–30]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.pteridosperm - an extinct seed-producing fernlike plant of the order Cycadofilicales (or group Pteridospermae)pteridosperm - an extinct seed-producing fernlike plant of the order Cycadofilicales (or group Pteridospermae)
gymnosperm - plants of the class Gymnospermae having seeds not enclosed in an ovary
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References in periodicals archive ?
Although diversity decreased towards the Griesbachian (basal Early Triassic) the Gymnosperms continued dominating the vegetation mosaic shared with pteridosperm.
Here I describe an upright tree of Macroneuropteris scheuchzeri rooted above the Point Aconi Coal in the Middle Pennsylvanian Sydney Mines Formation of Nova Scotia--the first example of an autochthonous pteridosperm described in the literature.
This is followed by a rather coarse volcanic ash band with large fragments of the presumed pteridosperm Alethopteris brevis Weiss.
Some pteridosperm stems and fructifications with particular reference to the Medullosae.
Cuticular analysis appears to be especially valuable for elucidating pteridosperm scrambling/climbing aids (cf.
From Sydney Coalfield, one pteridosperm seed attached to foliage Of Neuropteris flexuosa is known (Zodrow and McCandlish 1980) which emphasizes the rarity of attached female organs to determinable foliage.
Fossil orbicules are also found in pteridosperm pollen organs (e.
The evidence, such as it is, of preserved alethopterid biomass favours that the undetermined alethopterid foliage was borne on the interpreted 5-7 m tall pteridosperm tree.
Among different plant groups Pteridosperms were also trying to coope with theenvironment as shown by their morphographic features like radial monosaccate construction helpful in floating of pollen during dispesal , leathery saccus construction and saccus enclosing the corpus from all sides for the protection of microgametophte .
Evidence for pollination-drop mechanism in Paleozoic pteridosperms.