Carex huangshanica (sect. Rhomboidales, Cyperaceae), a new species from Anhui, eastern China

Carex huangshanica X. F. Jin & W. J. Chen, a new species from Anhui Province of eastern China, is described and illustrated. It belongs to Carex sect. Rhomboidales and resembles C. longirostrata in having perigynia gradually contracted into a long beak at apex; orifice 2-lobed with long teeth; achenes abruptly contracted into a beak at apex. It differs from C. longirostrata in having upper spikes aggregated, pistillate scales shortly awned at apex, perigynia nearly glabrous, and achenes ovoid. Micromorphological characters of the perigynia and achenes under scanning electron microscope are compared between the new species and C. longirostrata. Carex huangshanica has glabrous perigynia (vs. pubescent perigynia in C. longirostrata), achenes abruptly contracted in a short curved beak at apex, and only one silica body is present in each epidermal cell (vs. achenes of C. longirostrat that are contracted in a short coiled beak at apex, and without silica body in epidermal cells).

Bioactive Porous Silica Ceramics Prepared Using Rice Husk Ash by Gelcasting Method

Silica-based porous bioactive ceramics was prepared by gel-casting method using silica xerogel powder. Xerogel was derived from rice husk ash. 42 vol.% solid containing slurry was prepared in 1:30 (MBAM:AM) monomer cross-linker solution. The srurry was thixotropic. Gel-casted body was machined efficiently. Dired cast body was sintered at 1100oC. Apatite layer was formed on silica body during In vitro bioactivity experiment. The results suggest that the gel-casted silica ceramics can be used as a bioceramics.

Silica bodies and their systematic implications at the subfamily level in Podostemaceae

Podostemaceae is a family of eudicotyledonous rheophytes with unique morphology, sometimes resembling algae, lichens or bryophytes. This study evaluates the taxonomic value of silica-body morphology (presence, location, size, shape, ornamentation) in species representing the three subfamilies: Tristicha trifaria (Bory ex Willd.) Spreng. (Tristichoideae), Weddellina squamulosa Tul. (Weddellinoideae) and Diamantina lombardii Novelo, C.T. Philbrick & Irgang (Podostemoideae). T. trifaria and D. lombardii have silica bodies in stems and leaves. In contrast, W. squamulosa exhibits silica bodies only in the scale-like leaves. The morphology of these bodies is unique to each species. The results denote the taxonomic usefulness of silica characteristics and a need for a more complete study of silica bodies throughout the family.

Self‐potentials associated with the Yanacocha high‐sulfidation gold deposit in Peru

Significant self‐potential (SP) anomalies characterize the large silica bodies associated with high‐sulfidation oxide gold deposits in the Yanacocha district, Peru. Large SP effects and high apparent resistivities have been observed that coincide with areas of intense silicification. Negative SP anomalies of several volts have been routinely recorded on numerous projects and deposits. The peak value measured was −10.2 V. A direct relationship is shown to exist between the magnitude of an SP response and the size and apparent resistivity of a silica body. Extensive field measurements over numerous high‐sulfidation deposits show that the negative SP effect increases with the size and/or resistivity contrast associated with these unique mineral deposits.

Silica in Several Rattan Species

Summary The overall silica content in 10 rattan species was analyzed. Its distribution within the stem of Calamus merrillii Becc. was also tested. Anatomical observations were performed to explain the silica content variation. Ash and silica content varied among species. Regardless of diameter class, silica accounts for 44% to 48% of the overall ash content of the stem. Silica in the medium and small diameter stem was twice as much as in the large diameter stem. Within Calamus merrillii Becc., silica was abundant in the epidermal layer. It was responsible for 74% to 85% of the total silica content of the stem, which explains the variation in silica content between diameter classes. The proportion of epidermal layer contained in the sample deviated among the species causing a variation in silica content. Epidermal silica did not vary along the length of the stem while silica in the stem itself varied significantly from base to top. Differences in silica body frequency per vascular bundle caused such deviation.

The taxonomic and phylogenetic utility of vegetative anatomy and fruit epidermal silica bodies in Carex section Phyllostachys (Cyperaceae)

In Carex, vegetative anatomy and fruit epidermal silica bodies have been used to delimit species and sections, although frequent conflicts with traditional classifications have led many authors to question whether they can be used to infer evolutionary relationships. This conclusion, however, has largely been drawn from poorly circumscribed groups that have not been phylogenetically analyzed. This study was undertaken to assess the taxonomic and phylogenetic utility of these characters within Carex section Phyllostachys, a small (eight species), monophyletic group whose taxonomy and phylogeny has been extensively studied. Leaf and culm anatomy clearly separate the close species pair of Carex backii Boott and Carex saximontana Mackenzie, and they provide unique characters that distinguish Carex latebracteata Waterfall and Carex juniperorum Catling, Reznicek, & Crins. Anatomical and silica body characters strongly support the recognition of three species within the Carex willdenowii Willdenow complex (Carex willdenowii s.s., Carex basiantha Steudel, Carex superata Naczi, Reznicek, & B.A. Ford). Although unique characters were lacking in Carex jamesii Schw., infraspecific variation in its silica bodies was consistent with the high levels of genetic and morphological variation previously detected. Silica body characters support groups that are congruent with previous phylogenetic hypotheses derived from both morphological and molecular data. In contrast, vegetative anatomy, in this and previous studies, supports contradictory groups suggesting that its use in future phylogenetic studies below the sectional level in Carex may be limited.Key words: Carex, anatomy, silica bodies, cladistics, species circumscription.