Michael D. Windham

Genetic diversity and gene flow in the endangered dwarf bear poppy, Arctomecon humilis (Papaveraceae)

Arctomecon humilis is a critically endangered species endemic to the Moenkopi shale of Washington County, Utah. Recovery plans for the species would be improved by an understanding of genetic diversity and gene flow among its remaining populations. Ten variable isozyme loci were used to calculate genetic diversity statistics for study populations. Westerly populations possessed higher levels of genetic variability than other populations at the same isozyme loci. Three of the populations exhibited significant deviations from Hardy-Weinberg expectations. No correlation existed between genetic distance and geographic distance. Most of the genetic diversity was distributed among populations with little gene flow between populations, suggesting that observed genetic differences may arise from genetic drift. For the westerly populations, similar genotypes were observed in the seedling and old age classes, while intermediate age classes typically possessed an alternate set of genotypes at Pgi-2. Mean heterozygosity increased with age class across populations. Westerly populations of A. humilis shared more alleles with the nearest geographic population of A. californica than other populations. Since the westerly populations contained more genetic variability and more alleles in common with a near relative, they may be relictual. Other populations may contain less genetic diversity due to founder effects and/or genetic drift.

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

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.

NEW AND NOTEWORTHY SPECIES OF BOECHERA (BRASSICACEAE) I: SEXUAL DIPLOIDS

ABSTRACT On the basis of a critical examination of the type collections of all taxa described in Arabis and Boechera from North America, we propose the following nomenclatural adjustments among the sexual diploid taxa. Seven new species of Boechera (B. evadens, B. rollinsiorum, B. serpenticola, B. shevockii, B. texana, B. ultraalsa, B. villosa) are described and new names are proposed for the taxa originally described as A. pulchra var. munciensis (B. lincolnensis) and A. breweri var. austinae (B. breweri ssp. shastaensis). Ten new combinations (B. arcuata, B. atrorubens, B. fernaldiana ssp. vivariensis, B. formosa, B. howellii, B. nevadensis, B. paupercula, B. pendulocarpa, B. polyanthua, B. spatifolia) are validated. Notes on the delimitation, distribution, and/or typification of B. davidsonii, B. holboellii, B. johnstonii, B. lignifera, B. lyallii, B. microphylla, B. pallidifolia, B. pendulina, B. retrofracta, B. sparsiflora, and B. subpinnatifida are presented, with the last species reported for the first time from Idaho, Nevada, and Utah. Arabis davidsonii var. parva, A. demissa, A. hirshbergiae, and A. thompsonii are reduced to synonymy under B. davidsonii, B. oxylobula, B. johnstonii, and B. pallidifolia, respectively.

NEW AND NOTEWORTHY SPECIES OF BOECHERA (BRASSICACEAE) II: APOMICTIC HYBRIDS

ABSTRACT The following nomenclatural adjustments are proposed for the apomictic, hybrid species of Boechera to make the names available for the forthcoming account of the Brassicaceae in the Flora of North America. Two new species of Boechera (B. elkoensis and B. peirsonii) are described, and a new name (B. cascadensis) is proposed for the taxon currently known as Arabis microphylla var. thompsonii. In addition, 13 new combinations (B. calderi, B. californica, B. consanguinea, B. depauperata, B. drepanoloba, B. harrisonii, B. horizontalis, B. macounii, B. paddoensis, B. pauciflora, B. pinetorum, B. porphyrea, B. rubicundula) are validated. Notes on the delimitation and/or distribution of B. calderi, B. falcatoria, and B. goodrichii are presented. Boechera calderi is reported for the first time from California, Idaho, Montana, Oregon, Washington, and Wyoming, and B. goodrichii is reported for the first time from Nevada.

NEW AND NOTEWORTHY SPECIES OF BOECHERA (BRASSICACEAE) III: ADDITIONAL SEXUAL DIPLOIDS AND APOMICTIC HYBRIDS

ABSTRACT The following nomenclatural adjustments are proposed for Boechera to make the names available for the forthcoming account of the Brassicaceae in the Flora of North America. Two new species of Boechera (B. quebecensis and B. tularensis) are described, and a new name (B. xylopoda) is proposed for the taxon currently known as Boechera pulchra var. gracilis. In addition, 10 new combinations (B. acutina, B. burkii, B. covillei, B. duchesnensis, B. gracilenta, B. grahamii, B. languida, B. pratincola, B. saximontana, and B. serotina) are validated. Notes on the delimitation, distribution, and/or typification of Arabis confinis, B. brachycarpa, B. divaricarpa, and B. inyoensis are presented, and A. codyi and A. holboellii var. derensis are reduced to synonymy under B. lemmonii and B. inyoensis, respectively. Two summary tables comparing our taxonomic treatment of Boechera with those of other recent authors are provided.

New or Noteworthy North American Draba (Brassicaceae)

ABSTRACT The following nomenclatural adjustments are proposed for Draba to make the names available for the forthcoming account of the Brassicaceae in the Flora of North America. Three new species of Draba (D. abajoensis, D. malpighiacea, and D. santaquinensis) are described, and two new combinations (D. bifurcata and D. serpentina) are validated. Notes on the delimitation, distribution, or typification of D. corrugata, D. cyclomorpha, D. demareei, D. helleriana, D. lemmonii, D. longisquamosa, D. novolympica, D. oreibata, D. paysonii, D. petrophila, D. saxosa, D. spectabilis, and D. viridis are presented. Draba helleriana var. blumeri, D. paysonii var. treleasii, and D. spectabilis var. glabrescens are reduced to synonymy under D. petrophila, D. novolympica, and D. abajoensis, respectively.