Aspidotis is a small genus of leptosporangiateferns 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]
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]
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 sectionofHypolepis, 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]
As of January 2020[update], the Checklist of Ferns and Lycophytes of the World recognized five species,[6] including one identified as a fertile interspecific hybrid.[7]
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
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.
Ferns in this genus grow in a variety of conditions, from low woodland slopes,[2]tochaparral, 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 populationsofA. 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]
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]
^ abcdFlora of North America Editorial Committee, ed. (4 Nov 1993). Pteridophytes and Gymnosperms. Flora of North America: North of Mexico. Vol. 2. Oxford University Press. pp. 170–171. ISBN978-0-19-508242-5.
^Kramer, K.U.; Green, P.S.; Kubitzki, K., eds. (Jan 1990). Pteridophytes and Gymnosperms. The Families and Genera of Vascular Plants. Vol. 1. Springer. p. 242. ISBN978-3-540-51794-8.
