James M. Affolter

Adventitious bud development and regeneration in Tillandsia eizii.

SummaryThe bromeliad Tillandsia eizii is a stricking species with large, colorful, and persistent inflorescences that can reach 1 m in length. The value of this plant as an ornamental and its importance in cultural and religious activities has led to its overcollection in the wild. Clonal propagation via tissue culture may be a means to repopulate native stands while meeting the demands for this species as an ornamental and ceremonial plant. Adventitious bud proliferation was induced from axenically germinated scedling material. Parameters evaluated were the age of explant material at the time of transfer onto bud-induction medium, the concentration of plant growth regulators, and the period of exposure to induction medium. Light and seanning electron microscopy (SEM) established the origin and development of buds. Twelve-week-old seedling explants rapidly initiated adventitious buds after a 30-d induction period on shoot-initiation medium. Adventitious buds were induced in 40% of the explants placed on media with 2 mg l−1 6-benzylaminopurine (BA) (8.88 μM) plus 0.1 mg l−1 α-naphthaleneacetic acid (NAA) (0.54 μM) with some cultures becoming highly prolific after repeated subeulture. Shoots elongated in proliferating cultures, and plants were successfully acclimatized and planted into the greenhouse. The results indicate that tissue culture may be used as a means to propagate this epiphytic bromeliad species, which is being seriously affected by deforestation and habitat destruction. In addition, adventitious bud proliferation can provide a means to propagate superior genotypes.

A Phylogenetic and Biogeographic Study of the Genus Lilaeopsis (Apiaceae Tribe Oenantheae)

Abstract The genus Lilaeopsis (Apiaceae subfamily Apioideae) comprises 15 species and exhibits both American amphitropic and amphiantarctic patterns of disjunction. The group is difficult taxonomically because of its simplified habit, phenotypic plasticity of vegetative characters, and extensive variation in fruit characters. Sequence data from the nrDNA ITS and cpDNA rps16 intron and rps16-trnK intergenic spacer regions were obtained for 60 accessions, representing 13 species of Lilaeopsis and five closely related outgroup genera from the North American Endemics clade of tribe Oenantheae. These molecular data were subjected to maximum parsimony, Bayesian inference, and dispersal-vicariance analyses in an effort to reconstruct evolutionary relationships and infer biogeographic scenarios. The results suggest that: (1) L. macloviana, L. masonii, and L. occidentalis, distributed in western South America and western North America, collectively represent a single, polymorphic species of amphitropic distribution; (2) The Australasian species L. brisbanica, L. novae-zelandiae, L. polyantha, and L. ruthiana comprise a well-supported clade. However, L. novae-zelandiae is not monophyletic, but may be rendered so by the inclusion of all Australasian taxa into one polymorphic species; (3) L. mauritiana from Mauritius is closely related to L. brasiliensis from South America and may even be subsumed under the latter pending further investigation; and (4) Lilaeopsis probably originated in South America following a dispersal of its ancestor from North America. A minimum of seven dispersal events is necessary to explain its present-day distribution, including one dispersal from South America to Australia or New Zealand, two dispersals between Australia and New Zealand, and three dispersals from South America to North America.

Spatial and temporal distribution of the alkaloid sanguinarine in Sanguinaria canadensis L. (Bloodroot)

Acclimated and non-acclimated potted plants of Sanguinaria canadensis L. were harvested at early and late dormancy, anthesis, and immature and mature fruiting stages. Sanguinarine content and concentration were determined for rhizomes (distal, proximal, and middle sections), roots, leaves, flower, and fruit. Rhizomes had highest sanguinarine content and concentrations, and exhibited decreasing concentration gradients from the distal to proximal third. Concentrations in roots were a tenth of rhizome concentration. Concentrations in leaves, flowers, and fruit were one-thousandth of rhizome Sanguinarine content in whole acclimated plants was constant. Content in whole nonacclimated plants increased as the plant became physiologically active, but was constant during fruit maturation: content in roots, leaves, and fruit did not change. The substantial increase in whole-plant dry weight coupled with the unchanging sanguinarine content during fruit maturation suggests either a shift in photosynthate allocation from defense to growth, or a constant turnover of sanguinarine.

Three new species and a new combination in Arracacia Bancroft (Umbelliferae/Apiaceae)

Three species ofArracacia—A. hintonii, A. colombiana, andA. tillettii—from Mexico, Colombia, and Venezuela, respectively, are described as new, andCoulterophytum brevipes Coulter & Rose is transferred toArracacia asA. quadrifida, nom. nov. and comb. nov.

Using Prescribed Burning to Restore Granite Rock Outcrop Ecotones in the Piedmont of the Southeastern United States

Rock outcrop habitats in the Georgia Piedmont of the United States host many endemic and rare plants, and the sensitivity of these endemic species to fire is unknown. After surveying 2 granite rock outcrops for 1 yr, we applied a winter burn treatment to their margins to observe the effect of burning on the plant community. Using measures of vegetation class occurrence and species richness, along with hemispherical photographs, soil nutrients, and soil depth, we monitored the success of the restoration effort. Burning did not significantly alter soil nutrients, pH, or the abundance of different vegetation classes. In the 2–yr period following the prescribed burn, burning did not significantly increase canopy openness or noticeably alter total species richness or woody species richness. The burn treatment did not significantly change invasive species richness or abundance, and abundance of the 2 rare rock outcrop endemics present, tenpetal thimbleweed (Anemone berlandieri) and granite stonecrop (Sedum pusillum), was not significantly impacted. Prescribed fire has been used as an effective tool for managing forests in the Piedmont by clearing fuel buildup on the ground and suppressing invading secondary hardwoods. The findings of our study suggest that prescribed winter burns can be an appropriate management tool for outcrop ecotones, but rock outcrop habitats are variable and the benefits of prescribed fire should be evaluated on a site-specific basis.

A Trio of New Tauschias (Umbelliferae) from Eastern Mexico

Three new species are described in the genus Tauschia: T. hintoniorum from Coahuila and Nuevo Le6n, T. infernicola from Nuevo Le6n, and T. moorei from Hidalgo and Puebla.

Ecological Value of Native Plant Cultivars Versus Wild-Type Native Plants for Promoting Hemipteran Diversity in Suburban Areas

Abstract Because of concerns over recent declines in overall biodiversity in suburban areas, homeowners are attempting to improve the ecological functioning of their landscapes by incorporating native plants. Native plants are important for supporting native herbivorous insects, but it is unknown whether the native plants that are commercially available, typically cultivated varieties (cultivars) of a single genotype, are equally effective as food sources as the local, wildtype plants. We compared the hemipteran communities feeding on cultivars and wild-propagated plants for four species of native perennials commonly used as ornamentals. Of 65 hemipteran species collected, 35 exhibited a preference for some plant species over others, indicating a high degree of host-plant specialization. Moreover, the insect community associated with cultivars was distinct from the insect community associated with wild-type plants for each plant species, with three to four insect species accounting for most of the observed difference. Total insect abundance and insect biomass differed between cultivars and wild-propagated plants, but the direction of the difference changed over time and was not consistent among plant species. Species richness and a diversity index (the Q statistic) did not differ between cultivars and wild-type plants. These data suggest that abundance and diversity of hemipteran insects does not depend on the source of the plant material per se, but rather on the particular characteristics of cultivars that distinguish them from the wild type.

A pair of species of Tauschia Schltdl. (Umbelliferae/Apiaceae) from Mexico

Two species of Tauschia—T. spellenbergii from Chihuahua and T. beruloides from Michoacán and México—are described as new.