Search

The genusBotrychium(Ophioglossaceae) is comprised of about 30 widely distributed species. Because of their small size and few, yet variable, morphological characters, many questionable taxa have been described over the years. Since its description in 1906,B. duseniihas been treated as both a distinct species and variously divided into four taxa:B. lunariavar.dusenii,B. lunariavar.typicum,B. lunariavar.antarctica, andB. ramosumvar.patagonicum(B. matricariaefoliumsubsp.patagonicum). The aim of this study is to evaluate the validity of these taxa using spore wall sculpture, spore size, allelic composition employing enzyme electrophoresis, and morphological characters. We conclude that only one species ofBotrychiumoccurs in southern South America and recognize this asB. dusenii, a species distinct fromB. lunaria. Spore size and results of enzyme electrophoresis suggest thatB. duseniiis an allotetraploid derived through hybridization between a diploid member of theB. lunariacomplex and a diploid member of theB. campestrecomplex. We provide information about habitat, distribution, and full exsiccate citations. [ABSTRACT FROM PUBLISHER]

The article discusses a "proof of concept" study of a survey method for cost-effective recovery of depleted uranium (DU) fragments from the soil, performed at Sandia National Laboratories. A table summarizing the performance of 3 detectors that were used for measuring DU is presented. It was found that using the survey method based on the Environmental Restoration Group Inc. (ERG) Three-Dimensional Indoor Survey System (3-DISS), the cost to scan and remove the fragments and contaminated soils was about 65 dollars per cubic meter.

Gemmae are generally defined as vegetative propagules. In the shoestring ferns, Vittaria, gemmae grown in the presence of mature gametophyte plants or on medium containing gibberellic acid produce antheridia in lieu of vegetative growth. This suggests that antheridial differentiation in Vittaria is controlled by a chemical antheridogen system similar to those described in other fern genera. In natural populations of Vittaria gametophytes composed primarily of long-lived individuals, gemmae may provide the only source of tissue susceptible to antheridogen action and may have evolved in response to that condition.

Vegetative reproduction and dispersal by way of gemmae are known to occur in four types of fern gametophytes. Although they belong to basically tropical rain-forest genera, all four types have now been discovered growing natu rally in the vicinity of Highlands, North Carolina, as clones on shady, damp rocks. Their sporophytes were rare or absent. The gametophytes are now identified as Grammitis nimbata (Jenm.) Proctor, Grammitidaceae; Hymenophyllum tunbridg ense (L.) J.Sm., Hymenophyllaceae; Vittaria lineata (L.) J.Sm., Vittariaceae; and Trichomanes, probably representing several species, Hynmenophyllaceae. Identifi cation of the Grammitis was facilitated by the presence of some juvenile or dwarfed sporophytes; this constitutes the first report of this species, genus, and family for temperate North America. Growth and spread of fern gametophytes independently of, and distant from, the corresponding sporophytes is a novel phenomenon which should be investigated in other parts of the world.