Aspidotis

Aspidotis is a small genus of leptosporangiate ferns known commonly as laceferns. Most species are native to slopes, ridges, and rocky outcroppings, primarily in California and Mexico,[1] although one species included in the genus by some authorities is widely distributed in eastern Africa.[2]

Aspidotis
Aspidotis densa
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Class: Polypodiopsida
Order: Polypodiales
Family: Pteridaceae
Subfamily: Cheilanthoideae
Genus: Aspidotis
(Nutt. ex Hook.) Copel.
Species

See text.

Description

Members of Aspidotis are small ferns, with shiny, tufted fronds generally less than 35 centimeters long (although A. schimperi may be larger[2]). Fertile leaves have false indusia formed by the leaves' inrolled margins, which partially conceal the spore-bearing sori.[1][3]

Taxonomy

The taxonomy of laceferns has been considerably refined since they were first described in the late 1800s. Species currently placed in Aspidotis were originally assigned to a section of Hypolepis, then to Cheilanthes. David Lellinger established Aspidotis as a distinct genus based on characteristic features of its false indusia and its leaves, including their shiny surface,[4] although as late as the 1990 publication of the Kubitzki system, these ferns were sometimes still included in Cheilanthes.[5]

Species

As of January 2020, the Checklist of Ferns and Lycophytes of the World recognized five species,[6] including one identified as a fertile interspecific hybrid.[7]

  • Aspidotis californica (Nutt. ex Hook.) Nutt. ex Copel. – California lacefern
  • Aspidotis carlotta-halliae (Wagner & E. F. Gilbert) Lellinger – Carlotta Hall's lacefern or tufted lacefern, a fertile hybrid of A. californica and A. densa, endemic to California
  • Aspidotis densa (Brack.) Lellinger – cliffbrake or Indian's dream
  • Aspidotis meifolia (D.C.Eaton) Pic.Serm. – endemic to Mexico
  • Aspidotis schimperi (Kunze) Pic. Serm. – the African species

Other species of plants commonly known as laceferns are not part of Aspidotis and are often not closely related. Microlepia strigosa is from a different order of ferns, and Asparagus setaceus is not a fern at all.

Ecology

Ferns in this genus grow in a variety of conditions, from low woodland slopes,[2] to chaparral, to higher-elevation ridges, to marginal habitats like rocky crevices and the bases of boulders.[1][3]

Some laceferns show an affinity for serpentine soil. In particular, disjunct populations of A. densa in eastern North America are edaphic endemics.[8] A. carlotta-halliae and the West Coast populations of A. densa are commonly associated with these ultramafic soils but are not restricted to them.[9][10]

Etymology

Not all authorities agree on the exact etymology of Aspidotis. In all cases, the name is derived from Greek, and refers to the distinctive shield-like false indusium found especially in A. californica. Some authors suggest ασπιδοτες (shield-bearer)[1] as the intended origin, while others claim ασπιδος-ωτος (shield-eared).[11]

References
  1. Flora of North America Editorial Committee, ed. (4 Nov 1993). Pteridophytes and Gymnosperms. Flora of North America: North of Mexico. 2. Oxford University Press. pp. 170–171. ISBN 978-0-19-508242-5.
  2. Beentje, H. J., ed. (1 Jun 2002). Flora of Tropical East Africa - Adiantaceae. A. A. Balkema Publishers. pp. 2–3. ISBN 978-90-5809-410-0.
  3. Smith, A. Reid (1975). "The Californian species of Aspidotis". Madroño. 23 (1): 15–24.
  4. Lellinger, David B. (1968). "A Note on Aspidotis". American Fern Journal. 58 (3): 140–141. doi:10.2307/1546553. JSTOR 1546553.
  5. Kramer, K.U.; Green, P.S.; Kubitzki, K., eds. (Jan 1990). Pteridophytes and Gymnosperms. The Families and Genera of Vascular Plants. 1. Springer. p. 242. ISBN 978-3-540-51794-8.
  6. Hassler, Michael & Schmitt, Bernd (November 2019). "Oeosporangium". Checklist of Ferns and Lycophytes of the World. 8.11. Retrieved 2020-01-01.
  7. Wagner Jr., W.H.; Gilbert, Elizabeth F. (Nov 1957). "An Unusual New Cheilanthoid Fern from California". American Journal of Botany. 44 (9): 738–743. doi:10.2307/2438394. JSTOR 2438394.
  8. Harris, Tanner; Rajakaruna, Nishanta (2009). "Adiantum viridimontanum, Aspidotis densa, Minuartia marcescens, and Symphyotrichum rhiannon: Additional Serpentine Endemics from Eastern North America". Northeastern Naturalist. 16 (sp5): 111–120. doi:10.1656/045.016.0509. S2CID 54871497.
  9. Howell, John Thomas (Jan–Mar 1960). "The Endemic Pteridophytes of the California Floral Province". American Fern Journal. 50 (1): 15–25. doi:10.2307/1545239. JSTOR 1545239.
  10. Safford, H. D.; Viers, J. H.; Harrison, S. P. (2005). "Serpentine Endemism in the California Flora: A Database of Serpentine Affinity". Madroño. 52 (4): 222–257. doi:10.3120/0024-9637(2005)52[222:seitcf]2.0.co;2.
  11. Gledhill, David (17 Mar 2008). The Names of Plants (4th ed.). Cambridge University Press. p. 59. ISBN 978-0-521-86645-3.
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