The Cytology of Some Species of the Genus Notholaena

Although analyses of chromosome numbers represent a fundamental step in the study of any group of organisms, the xeric-adapted cheilanthoid ferns (Pteridaceae: subfamily Cheilanthoideae) have received little attention from cytogeneticists due to the difficulty in obtaining samples and accurate chromosome counts. In an effort to clarify patterns of chromosomal evolution in this group, we present 131 chromosome counts representing 75 taxa of cheilanthoid ferns from the western United States and Mexico. First reports are provided for 24 taxa, including the first count for the genus Cheiloplecton. Nine other taxa yielded numbers that had not been reported previously. Our data suggest that chromosome base numbers are more stable than previously thought and that much of the reported variation may involve erroneous counts. When coupled with published DNA sequence data, our counts suggest that the plesiomorphic base number of subfamily Cheilanthoideae is x = 30 and that x = 29 has arisen just once or twice among the taxa studied.

Section: Cheiloplecton-although Included Insupporting

confidence: 92%

Section: Cheilanthes (''Brandegei Group'')-supporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Section: Aspidotis-although Aspidotis Is Sometimes Included Inmentioning

confidence: 98%

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Chromosome studies of cheilanthoid ferns (Pteridaceae: Cheilanthoideae) from the western United States and Mexico

Windham

Yatskievych

2003

Infraspecific diversification of the star cloak fern (Notholaena standleyi) in the deserts of the United States and Mexico

Kao

Rothfels

Melgoza‐Castillo

et al. 2020

2020. Infraspecific diversification of the star cloak fern (Notholaena standleyi) in the deserts of the United States and Mexico.PREMISE: Not all ferns grow in moist and shaded habitats. One well-known example is Notholaena standleyi, a species that thrives in deserts of the southwestern United States and Mexico. This species exhibits several "chemotypes" that differ in farina (flavonoid exudates) color and chemistry. By integrating data from molecular phylogenetics, cytology, biochemistry, and biogeography, we circumscribed the major evolutionary lineages within N. standleyi and reconstructed their diversification histories. METHODS:Forty-eight samples were selected from across the geographic distribution of N. standleyi. Phylogenetic relationships were inferred using four plastid and five nuclear markers. Ploidy levels were inferred using spore sizes calibrated by chromosome counts, and farina chemistry was compared using thin-layer chromatography. RESULTS:Four clades are recognized, three of which roughly correspond to previously recognized chemotypes. The diploid clades G and Y are found in the Sonoran and Chihuahuan deserts, respectively; they are estimated to have diverged in the Pleistocene, congruent with the postulated timing of climatological events separating these two deserts. Clade P/YG is tetraploid and partially overlaps the distribution of clade Y in the eastern Chihuahuan Desert. It is apparently confined to limestone, a geologic substrate rarely occupied by members of the other clades. The cryptic (C) clade, a diploid group known only from southern Mexico and highly disjunct from the other three clades, is newly recognized here. CONCLUSIONS:Our results reveal a complex intraspecific diversification history of N. standleyi, traceable to a variety of evolutionary drivers including classic allopatry, parapatry with or without changes in geologic substrate, and sympatric divergence through polyploidization.

Chemical Variation in Notholaena Standleyi

Seigler

Wollenweber

1983

In Notholaena standleyi (Pteridaceae), differences in geographic range, aspect, height, edaphic requirements, and the color and chemistry of the ceraceous exudate on the abaxial side of the frond suggest at least three distinct subgroups ofthis taxon. One race, with a light yellow exudate consisting mostly ofkaempferol, 3-0-methylkaempferol and 4'-0-methylkaempferol occurs in the eastern portion of the range. A yellow-green race and a gold race possess mostly 7-0methylkaempferol and 4' -O-methylkaempferol but also the uncommon compounds 7-O-methylherbacetin and 7,4'-di-0-methylherbacetin. Plants of the yellow-green race produce minor constituents with methyl substituents in the 3-position whereas those ofthe gold race lack them. Plants of this last group produce only traces of kaempferol.Principal Components Analysis based on nine flavonoid constituents and 59 samples was carried out. Plants ofthe three groups clustered in plots of Principal Components I vs. 2, I vs. 3, and 2 vs. 3 and were separated from each other.These plants reproduce ameiotically and thus there is little or no gene fk, among them and they are geographically distinct. We prefer to maintain them as informally recognized taxa pending further studies.