Galax, a monotype endemic to the southern Appalachian Mountains and outlying areas, has been reported to comprise both a diploid and tetraploid cytotype (x = 6). In this study more than 850 ...chromosome counts of Galax urceolata from 460 locations, including numerous intra-populational counts, were made and mapped along with most of Baldwin's original counts in order to obtain a clear picture of the geographic distribution of the cytotypes. A strong correlation between guard cell size and chromosome number allowed estimation of ploidy level of herbarium collections. The diploid race occurs over most of the range of the species. Tetraploids occupy a relatively smaller portion of the range; they are abundant along the area of the Blue Ridge escarpment, sharply bounded on the northwest by the escarpment in northern North Carolina and by the Blue Ridge divide further south. On the Virginia coastal plain and north-central piedmont of North Carolina tetraploids occur exclusive of diploids. Along the escarpment diploids and tetraploids occur in complex patterns of sympatry and triploids are abundant, usually growing intermixed with or immediately adjacent to one of the other cytotypes. Along the escarpment there is much overlap in habitat preference, but commonly the more xeric habitats are occupied by diploids and the more mesic ones by tetraploids. No differences in habitat are apparent on the piedmont and coastal plain where the cytotypes are allopatric.
Ionactis caelestis Leary & Nesom is a new species known from a single population that occurs on the Aztec Sandstone near Bridge Mountain in the Spring Mountains of Clark County, Nevada. It is placed ...in the genus Ionactis (=Aster subg. Ianthe) on the basis of its crowded, multicipital crown, lack of persistent basal leaves and presence of densely arranged cauline ones, strongly carinate phyllaries, blue rays, disc style branches with linear-lanceolate appendages, asymmetric carpopodia, double pappus, and chromosome number of 2n = 9 II. A key to the four species of the genus emphasizes the distinction of the new species in its taproot, the abundant, large, glandular trichomes on its stems and leaves, and disc flowers with sterile ovaries. Ionactis is more similar to the goldenaster (Heterotheca) lineage than to Aster, with which it has been allied formerly. The core of the goldenaster genera differ from Ionactis primarily in their yellow-rayed heads, the crystal complement within cells of their disc corollas, and their primarily multinerved achenes.
Chaptalia dentata (L.) Cass. and C. albicans (Sw.) Vent. ex Steudel incorrectly have been recognized as conspecific in recent treatments. Although they are vegetatively similar, they differ in ...features of the flowers and fruits-especially the mature achenes. Both species occur in the Bahamas and the Greater Antilles of the West Indies: Chaptalia dentata is endemic to that area, absent only from Jamaica; C. albicans is more widespread, as it occurs in Jamaica as well as in scattered localities on the American mainland-southern Florida, various localities in Belize, Honduras, and Guatemala, and the Mexican states of Veracruz, San Luis Potosi, Chiapas, and Yucatan.
Hedyotis spellenbergii Nesom & Vorobik is described from west-central Chihuahua, Mexico, where it appears to be endemic to the area of Basaseachic. It is a member of the "H. rubra group," which is ...characterized primarily by recurved fruiting pedicels and deeply concave seeds. The new species is most similar to H. cervantesii but is distinctive in its prostrate, mat-forming habit and salverform corollas. In addition, the following new combinations to Hedyotis are made: H. butterwickiae (Terrell) Nesom, H. kingii (Terrell) Nesom, H. sharpii (Terrell) Nesom, and H. teretifolia (Terrell) Nesom.
We have made the first measurement of the double-inclusive B/B energy distribution in e+e− annihilations, using a sample of 400000 hadronic Z0-decay events recorded in the SLD experiment at SLAC ...between 1996 and 1998. The small and stable SLC beam spot and the CCD-based vertex detector were used to reconstruct B/B-decay vertices with high efficiency and purity, and to provide precise measurements of the kinematic quantities used to calculate the B energies in this novel technique. We measured the B/B energies with good efficiency and resolution over the full kinematic range. We measured moments of the scaled energies of the B and B hadrons vs. the opening angle between them. By comparing these results with perturbative QCD predictions we tested the ansatz of factorisation in heavy-quark production. A recent next-to-leading order calculation reproduces the data.
Chaptalia transiliens Nesom, a new species from Mexico, is described and assigned to Chaptalia sect. Leria; notes on its distribution and phenology are given.
Recent collections of Aster blepharophyllus A. Gray, the first since its discovery in 1851, prompted a reevaluation of its identity. It is properly placed in the genus Machaeranthera as M. ...gypsitherma Nesom, Vorobik, & Hartman. Within that genus, it shares characters with species of sect. Blepharodon as well as those of sect. Arida (both groups sensu Hartman), but we place it tentatively in the latter group. Of particular significance is its chromosome number of n = 5 pairs, reported for the first time, which is shared with species of sect. Arida.
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