Aspidotis Explained

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]

Description

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

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

• 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, to chaparral, to higher-elevation ridges, to marginal habitats like rocky crevices and the bases of boulders.

Some laceferns show an affinity for serpentine soil. In particular, disjunct populations of A. densa in eastern North America are edaphic endemics.^[7] A. carlotta-halliae and the West Coast populations of A. densa are commonly associated with these ultramafic soils but are not restricted to them.^{[8] [9]}

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) as the intended origin, while others claim ασπιδος-ωτος (shield-eared).^[10]

Notes and References

1. Book: Flora of North America Editorial Committee. Pteridophytes and Gymnosperms. Flora of North America: North of Mexico. 2. Oxford University Press. 4 Nov 1993. 978-0-19-508242-5. 170–171.
2. Book: Beentje. H. J.. Henk Jaap Beentje. Flora of Tropical East Africa - Adiantaceae. 2–3. A. A. Balkema Publishers. 1 Jun 2002. 978-90-5809-410-0. Beentje02. Flora of Tropical East Africa.
3. Smith. A. Reid. The Californian species of Aspidotis. Madroño. 23. 1. 15–24. 1975.
4. Lellinger. David B.. David B. Lellinger. A Note on Aspidotis. American Fern Journal. 58. 3. 140–141. 1968. 10.2307/1546553. 1546553.
5. Book: Kramer. K.U.. Green. P.S.. Kubitzki. K.. Pteridophytes and Gymnosperms. The Families and Genera of Vascular Plants. 1. Springer. Jan 1990. 242. 978-3-540-51794-8.
6. Wagner Jr.. W.H.. Warren H. Wagner. Gilbert. Elizabeth F.. An Unusual New Cheilanthoid Fern from California. American Journal of Botany. 44. 9. Nov 1957. 738–743. 10.2307/2438394. 2438394.
7. Harris. Tanner. Rajakaruna. Nishanta. Adiantum viridimontanum, Aspidotis densa, Minuartia marcescens, and Symphyotrichum rhiannon: Additional Serpentine Endemics from Eastern North America. Northeastern Naturalist. 16. sp5. 2009. 111–120. 10.1656/045.016.0509. 54871497.
8. Howell. John Thomas. John Thomas Howell. The Endemic Pteridophytes of the California Floral Province. American Fern Journal. 50. 1. Jan–Mar 1960. 15–25. 10.2307/1545239. 1545239.
9. Safford. H. D.. Viers . J. H. . Harrison . S. P. . Serpentine Endemism in the California Flora: A Database of Serpentine Affinity. Madroño. 52. 4. 222–257. 2005 . 10.3120/0024-9637(2005)52[222:seitcf]2.0.co;2. 84632195.
10. Book: Gledhill, David. The Names of Plants. limited. 4th. Cambridge University Press. 59. 17 Mar 2008. 978-0-521-86645-3.