Aspidotis, commonly known as laceferns, is a small genus of leptosporangiate ferns in the family Pteridaceae (order Polypodiales). The genus comprises around five species, with most native to slopes, ridges, and rocky outcroppings primarily in California and Mexico, and one species, A. schimperi, widely distributed in eastern Africa.
Members of Aspidotis are small ferns with shiny, tufted fronds typically less than 35 centimetres long. A defining feature of the genus is the false indusium — a protective covering for the spore-bearing sori formed not by a true flap of tissue but by the inrolled margins of the fertile leaf. This distinctive shield-like false indusium was the basis on which David Lellinger formally established Aspidotis as a genus separate from Cheilanthes, where species had previously been placed (and sometimes still appeared as late as the Kubitzki system of 1990). Before that, the group had been treated as a section of Hypolepis.
Notable members include Aspidotis californica (California lacefern), Aspidotis densa (cliffbrake or Indian's dream), and A. carlotta-halliae — a fertile interspecific hybrid of the two, endemic to California. The genus occupies a range of habitats from low woodland slopes and chaparral to high-elevation rocky ridges, and some species show a particular affinity for ultramafic (serpentine) soils.
Etymology
The name Aspidotis is derived from Greek and refers to the genus's distinctive shield-like false indusium, which partially covers the sori on fertile fronds. Authorities disagree on the precise root: some propose ασπιδοτες (shield-bearer), while others favor ασπιδος-ωτος (shield-eared).
Distribution
Aspidotis is distributed primarily in California and Mexico, where species occupy slopes, ridges, chaparral, and rocky outcroppings. Disjunct populations of A. densa occur in eastern North America as edaphic endemics on serpentine soils. Aspidotis schimperi extends the genus's range to eastern Africa.
Ecology
Laceferns in Aspidotis tolerate a wide range of conditions, from low woodland slopes and chaparral to high-elevation ridges and marginal habitats such as rocky crevices and the bases of boulders. A notable ecological trait in the genus is an affinity for serpentine (ultramafic) soils — A. carlotta-halliae and West Coast populations of A. densa are commonly associated with these mineral-rich substrates, while eastern North American populations of A. densa are strict edaphic endemics restricted to them.
Taxonomy Notes
The taxonomy of Aspidotis has been substantially revised since species were first described in the late 1800s. They were originally assigned to a section of Hypolepis, then transferred to Cheilanthes. David Lellinger segregated Aspidotis as an independent genus based on the characteristic false indusia and the distinctive shiny leaf surface; some treatments continued to include these ferns in Cheilanthes as late as the 1990 Kubitzki system. GBIF places the genus in family Pteridaceae, order Polypodiales.
