Pertica

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For other uses, see Pertica (disambiguation).

Pertica
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Embryophytes
Clade: Polysporangiophytes
Clade: Tracheophytes
Clade: Euphyllophytes
Genus: †Pertica
Kasper & H.N.Andrews (1972)[1]
Species
  • P. dalhousii Doran et al. (1978)[2]
  • P. quadrifaria Kasper & H.N.Andrews (1972)[1]
  • P. varia Granoff et al. (1976)[3]

Pertica is a

paraphyletic group of early members of the lineage leading to modern ferns and seed plants.[4]

Description

Pertica quadrifaria (the

dichotomously, branching many times at increasingly shorter intervals. Some of the terminal branchlets bore masses of erect paired, ellipsoidal sporangia in distinctive tight clusters. The branches were arranged in a spiral pattern, forming four vertical rows. The specific epithet quadrifaria refers to this growth habit.[1][5][6]

Pertica varia was described in 1976 from the Devonian of Eastern Canada. It was considerably taller than P. quadrifaria, reaching a height of nearly 3 m. The sporangia were similar to those of P. quadrifaria, although there were fewer in each cluster.[7]

Pertica dalhousii was described in 1978 from fossils of Early or Middle Devonian age found in New Brunswick, Canada. The plant appears to have been similar to P. quadrifaria (only part is known), comprising a central stem (axis) with spirally arranged dichotomous side branches, some of which terminated in erect clusters of between 32 and 128 sporangia. Further specimens from the same rocks possibly belonged to another species of Pertica, but were not sufficiently well preserved to be named.[2]

Phylogeny

The clear differentiation between a main stem (axis) and lateral branches in Pertica, as in other "trimerophytes", has been considered to represent an early stage in the development of a growth pattern that later led to the evolution of

stem group basal to the seed plants (spermatophytes) which have such leaves.[8]

euphyllophytes

† Eophyllophyton

† basal groups (Psilophyton crenulatum, Ps. dawsonii)

moniliforms
(ferns; extant and extinct members)

† basal groups (Pertica, Tetraxylopteris)

spermatophytes
(seed plants; extant and extinct members)

Other researchers have produced rather different analyses. Rothwell's analysis separates "trimerophytes", like Pertica, from

progymnosperms, like Tetraxylopteris, with only the latter being closely related to seed plants.[9]

References

  1. ^
    JSTOR 2441116
  2. ^
    doi:10.1139/b78-369
  3. doi:10.1016/S0034-6667(97)00010-9
  4. ISBN 978-0-12-373972-8
    , pp. 259-261
  5. JSTOR 1219491
  6. doi:10.1016/0034-6667(80)90056-1
  7. ^ Taylor, Taylor & Krings 2009, p. 261
  8. PMID 21652317
  9. S2CID 40215551
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