bluuebunny/crossref_metadata_2025 huggingface dataset:
Clarification of the relationship between Apiaceae and Araliaceae based on matK and rbcL sequence data
Authors: Plunkett Gregory M. , Soltis Douglas E. , Soltis Pamela S.
Published: April 2006

Apiaceae and Araliaceae (Apiales) represent a particularly troublesome example of the difficulty in understanding evolutionary relationships between tropical‐temperate family pairs. Previous studies based on rbcL sequence data provided insights at higher levels, but were unable to resolve fully the family‐pair relationship. In this study, sequence data from a more rapidly evolving gene, matK, was employed to provide greater resolution. In Apiales, matK sequences evolve an average of about two times faster than rbcL sequences. Results of phylogenetic analysis of matK sequences were first compared to those obtained previously from rbcL data; the two data sets were then combined and analyzed together. Molecular analyses confirm the polyphyly of apiaceous subfamily Hydrocotyloideae and suggest that some members of this subfamily are more closely related to Araliaceae than to other Apiaceae. The remainder of Apiaceae forms a monophyletic group with well‐defined subclades corresponding to subfamilies Apioideae and Saniculoideae. Both the matK and the combined rbcL‐matK analyses suggest that most Araliaceae form a monophyletic group, including all araliads sampled except Delarbrea and Mackinlaya. The unusual combination of morphological characters found in these two genera and the distribution of matK and rbcL indels suggest that these taxa may be the remnants of an ancient group of pro‐araliads that gave rise to both Apiaceae and Araliaceae. Molecular data indicate that the evolutionary history of the two families is more complex than simple derivation of Apiaceae from within Araliaceae. Rather, the present study suggests that there are two well‐defined “families,” both of which may have been derived from a lineage (or lineages) or pro‐araliads that may still have extant taxa.
Pollination by deceit in nutmeg (Myristica insipida, Myristicaceae): floral displays and beetle activity at male and female trees
Authors: Armstrong Joseph E.
Published: April 2006

Pollination by deceit in Myristica insipida, a beetle‐pollinated nutmeg, was hypothesized to operate on intersexual differences in flower production and longevity, producing a daily fluctuation between floral display maxima and minima. Sticky traps were used to continuously monitor beetle activity. Flower production and naturally occurring intersexual differences in display were recorded. Male and female trees flowered in synchrony producing daily display maxima at 1800–0600 and display minima at 1400–1800. Rewarding male trees produced three times the number of flowers of female trees, but the greater longevity of female flowers reduced the intersexual difference in display maxima to a factor of two. There was no intersexual difference in display minima. Beetles were demonstrated to be sensitive to differences in both maximum and minimum displays on rewarding male trees, a necessary prerequisite for directional selection on display size. Beetle captures were significantly higher at male trees during floral display maxima, and no intersexual differences in capture rate occurred during floral display minima. However, capture rates at male trees did not decline as predicted, and the pattern of captures was consistent with crepuscular activity. Beetle captures at male and female trees were lower from 1800 to 0600 and 1000 to 1400, and higher from 0600 to 1000 and 1400 to 1800, but the differences were only significant at female trees. These data suggests that foraging errors are numerous, frequent, and the result of overall foraging activity.
Patterns of wing size variation in seeds of the lily Cardiocrinum cordatum (Liliaceae)
Authors: Sakai Satoki , Sakai Akiko , Ishii Hiroshi S.
Published: April 2006

We examined the patterns of variation in wing‐loading and its related characteristics in Cardiocrinum cordatum to clarify the factors that determine the variation in seed dispersal ability in this species. The square root of wing‐loading of a seed of a plant was not significantly correlated with basal stem diameter of a plant, indicating that large plants did not necessarily produce seeds with high dispersal ability. This result was inconsistent with the hypothesis that large plants produce seeds with high dispersal ability to avoid high mortality of seeds and seedlings in the vicinity of the parents. On the other hand, the square root of wing‐loading of a seed of a fruit was negatively dependent on seed number of a fruit. Thus, many‐seeded fruits produced seeds with high dispersal ability. This was because the projected surface area per seed was large in large fruits and large fruits contained large numbers of seeds. The cost per seed of producing fruit structures was small for many‐seeded fruits. Thus, high dispersal ability of seeds in many‐seeded fruits may be a result of an effective resource allocation pattern in which a high proportion of resources are allocated to those many‐seeded fruits, enabling seeds to develop large wings and thus reducing the structural cost of fruits per seed.
Distance‐dependent performance of asexual progeny in Allium vineale (Liliaceae)
Authors: Ronsheim Margaret L.
Published: April 2006

Local adaptation within and among populations may have an impact on processes ranging from speciation to the evolution of mixed breeding systems and dispersal strategies. It is also one potential factor that could favor the production of asexual over sexual propagules. This field experiment tested whether asexually produced bulbils of Allium vineale demonstrate local adaptation to the parental microsite at the scale of natural dispersal from the parent (5, 25, 50, 100, and 1000 cm). Both “home” and randomly chosen “away” genotypes were planted at each location to determine the relative performance of the “home” genotype. Overall, bulbil performance declined with distance from the parent. In particular, “home” bulbils outperformed “away” bulbils at a distance of 25 cm from the parent, indicating that local adaptation has occurred at the scale of natural dispersal in this species. The variance in propagule performance also increased at farther distances from the parent, indicating that the predictability of offspring performance decreases with distance. Fine‐scale local adaptation within the range of seed dispersal in this population may be one factor favoring asexual reproduction in Allium vineale.
Perithecial ontogeny in the fungal genus Epichloë: An Examination of the Clavicipitalean centrum
Authors: White James F.
Published: April 2006

The structure and development of perithecia in five collections of Epichloë from Europe and North America were studied. Perithecia in early stages of development are oblong to ovate in overall shape. Dichotomously branched paraphyses form on the bottom and sides of the inner walls of the perithecial primordium. As the ovate primordium expands, a mound of ascogenous mycelium develops in its base. As asci develop from the ascogenous mound, paraphyses proximal to asci evanesce and no paraphyses are observable within the cluster of asci. In E. amarillans and E. baconii paraphyses are converted into pseudoparenchyma‐like tissues, while in E. typhina paraphyses remain filamentous until they evanesce. Ascospore development is seen to differ among all three species of Epichloë. The development and structure of the Epichloë centrum are compared to those of the Nectria and Xylaria types. It is apparent that a distinct type of centrum is present in Epichloë, and perhaps all of the Clavicipitaceae. It is proposed that the Epichloë type centrum may represent a key feature for distinguishing the Clavicipitaceae from the Hypocreaceae or other groups of pyrenomycetes.
The effect of interplant distance on mating Success in Federally Threatened, Self‐Incompatible Hymenoxys Herbacea = H. Acaulis var. glabra (Asteraceae)
Authors: Morán‐Palma Pedro , Snow Allison A.
Published: April 2006

We investigated large‐ and fine‐scale effects of interplant distance on compatibility, seed set, and seed germination in a rare, self‐incompatible perennial, Lakeside daisy (Hymenoxys herbacea = H. acaulis var. glabra). Plants were collected at the Marblehead Peninsula, Ohio, and transplanted to a greenhouse where they were hand‐pollinated. For the large‐scale analysis, 110 crosses were classified in three categories: Near crosses (0.75–6.70 m), Far crosses (17–72 m), and Very Far crosses (>900 m). There was no significant effect of interplant distance on compatibility, seed set, or seed germination in these crosses. For the fine‐scale analysis, we made 44 crosses with interplant distances ranging from 0.75 to 10 m. At this scale, interplant distance explained 10.9% of the variance of the seed/floret ratio, suggesting that local genetic structure may result in a modest amount of biparental inbreeding. We found no fine‐scale effects of interplant distance on compatibility or percentage of seed germination, but it is possible that biparental inbreeding could affect later stages of the life cycle not included in this study. For all distance classes, >80% of the crosses were compatible, indicating that lack of compatibility between mates is not likely to limit seed production. Apparently, presumed population bottlenecks have not been severe enough for genetic drift to eliminate substantial numbers of self‐incompatibility alleles.
Roles of the Af and Tl genes in pea leaf morphogenesis: characterization of the double mutant (afaftltl)
Authors: Villani Philip J. , DeMason Darleen A.
Published: April 2006

The pleiofila phenotype (afaftltl double mutant) of Pisum sativum arises from two single‐gene, recessive mutations known to affect the identity of leaf pinnae, afila (af), and acacia (tl). The wild‐type leaf consists of proximal leaflets and distal tendrils, whereas the pleiofila leaf consists of branched pinnae terminating in small leaflets. Using morphological measurements, histology, and SEM, we characterized the variation in leaf form along the plant axis, in leaflet anatomy, and in leaf development in embryonic, early postembryonic, and late postembryonic leaves of aftl and wild‐type plants. Leaves on aftl plants increase in complexity more rapidly during shoot ontogeny than those on wild‐type plants. Leaflets of aftl plants have identical histology to wild‐type leaflets although they have smaller and fewer cells. Pinna initiation is acropetal in early postembryonic leaves of aftl plants and in all leaves of wild‐type plants, whereas in late postembryonic leaves of aftl plants pinna initiation is bidirectional. Most phenotypic differences between these genotypes can be attributed to differential timing (heterochrony) of major developmental events.
Chloroplast DNA phylogeny, reticulate evolution, and biogeography of Paeonia (Paeoniaceae)
Authors: Sang Tao , Crawford Daniel J. , Stuessy Tod F.
Published: April 2006

The coding region of the matK gene and two intergenic spacers, psbA‐trnH and trnL(UAA)‐trnF(GAA), of cpDNA were sequenced to study phylogenetic relationships of 32 Paeonia species. In the psbA‐trnH intergenic spacer, short sequences bordered by long inverted repeats have undergone inversions that are often homoplasious mutations. Insertions/deletions found in the two intergenic spacers, mostly resulting from slipped‐strand mispairing, provided relatively reliable phylogenetic information. The matK coding region, evolving more rapidly than the trnL‐trnF spacer and more slowly than the psbA‐trnH spacer, produced the best resolved phylogenetic tree. The matK phylogeny was compared with the phylogeny obtained from sequences of internal transcribed spacers (ITS) of nuclear ribosomal DNA. A refined hypothesis of species phylogeny of section Paeonia was proposed by considering the discordance between the nuclear and cpDNA phylogenies to be results of hybrid speciation followed by inheritance of cpDNA of one parent and fixation of ITS sequences of another parent. The Eurasian and western North American disjunct distribution of the genus may have resulted from interrruption of the continuous distribution of ancestral populations of extant peony species across the Bering land bridge during the Miocene. Pleistocene glaciation may have played an important role in triggering extensive reticulate evolution within section Paeonia and shifting distributional ranges of both parental and hybrid species.
An electronic device for continuous, in vivo measurement of forces exerted by twining vines
Authors: Matista Anthony A. , Silk Wendy Kuhn
Published: April 2006

Contact forces are important in maintaining the twining habit of viny stems. A stem twining around a supporting pole puts itself into tension and uses a helical geometry to generate normal loads that are large relative to stem mass per unit length (Silk and Hubbard, Journal of Biomechanics 24(7):599–606, 1991). An electronic pressure‐sensing device has been constructed to provide continuous, in vivo measurements of the forces exerted by twining stems. The pressure‐sensing element is based on a thin beam load cell that is sheared by a twining stem ascending a split pole. Preliminary results show that after morning glory stems begin to coil around a supporting pole, the twining force increases in an oscillatory fashion over 3 or 4 d, corresponding to positions at least 200 mm from the apex. The force‐measuring device should reveal relationships between twining forces and developmental attributes or environmental factors.
The maryland mammoth allele reduces floral stimulus activity in stem piece explants of Nicotiana tabacum (Solanaceae)
Authors: Smith Susan M. E. , McDaniel Carl N. , Hartnett Laura K.
Published: April 2006

The response of axillary buds to floral stimulus activity in stem pieces was examined in two near‐isogenic cultivars of tobacco that differ in the recessive maryland mammoth (mm) allele, which confers short‐day behavior. All axillary buds from day‐neutral plants assayed on six‐internode stem pieces made few nodes (less than 20) before flowering, while axillary buds from plants homozygous for mm assayed on six‐internode stem pieces either did not flower in noninductive conditions or made many nodes before flowering in inductive conditions. About 80% of day‐neutral axillary buds grafted onto day‐neutral stem pieces did not respond to floral stimulus in stem pieces, indicating that the floral stimulus in stem pieces is ephemeral. In other graft combinations, the proportion of axillary buds that did respond to floral stimulus in stem pieces was substantially reduced from the 20% of day‐neutral buds on day‐neutral stem pieces that responded. These results indicate that the mm allele probably reduces both the amount of floral stimulus activity in stem pieces and the competence of axillary buds to respond.
Frequency and direction of hybridization in sympatric populations of pinus taeda and p. echinata (Pinaceae)
Authors: Edwards‐Burke Melinda A. , Hamrick J. L. , Price Robert A.
Published: April 2006

Two naturally occurring, sympatric, northern Georgia populations of Pinus taeda L. (loblolly pine) and P. echinata Mill. (shortleaf pine) were examined with respect to genetic diversity within populations and the frequency, spatial distribution, and morphology of putative hybrids. Shortleaf pine predominated at the “road” site while loblolly pine predominated at the “granite outcrop” site. Hybrid individuals were identified by their IDH allozyme genotype, the only such locus known to be fixed for different alleles in the two species. All allozymatically detectable hybrids (34 at the road site and two at the granite outcrop site) were juveniles that were distributed in open, sunny patches. A similar pattern of recruitment was seen for juveniles of the parental species. Hybrids were spatially distant from mature shortleaf pine, suggesting that shortleaf pine was not the seed parent. Discriminant analysis on needle characteristics indicated that loblolly pine was easily distinguished from shortleaf pine and the hybrids, but that shortleaf pine and the hybrids were barely distinguishable from each other. A diagnostic cpDNA restriction site marker indicated that shortleaf pine sired all the hybrids at both sites. No evidence of later generation hybridization was found.
Ontogenetic changes in size, allometry, and mechanical design of tropical rain forest trees
Authors: Sterck Frank J. , Bongers Frans
Published: April 2006

Size, allometry, and mechanical design were measured for trees of three canopy species in a tropical rain forest in French Guiana. Mechanical design was expressed as the safety factor, using the elastic‐stability model, and the wind resistance factor, using the constant‐stress model. Changes with ontogeny were described as regressions using stem diameter as the independent variable, and they were compared between species. Height, crown size, and the wind resistance factor increased with ontogeny. The safety factor decreased to a minimum and then increased continuously in thicker trees. The crown width/height ratio did not change with ontogeny. Interspecific differences in allometry and mechanical design were related to the adult stature of the species, and not to shade tolerance. The short stature species (Vouacapoua americana) was less slender (height:DBH [stem diameter at 1.3 m] ratio) and had a higher crown width/height ratio than the tall stature species (Goupia glabra and Dicorynia guianensis). Vouacapoua had a higher safety factor, but a similar wind resistance factor. The safety factors of our study species were lower than those of two temperate tree species because of a higher slenderness. Differences in safety factors between tropical and temperate trees may result from unrealistic assumptions of the elastic‐stability model, and may also be related to lower light levels and/or wind rates in the tropics.
Degradation of the upper pulvinus in modern and fossil leaves of Cercis (Fabaceae)
Authors: Owens Shirley A. , Fields Patrick F. , Ewers Frank W.
Published: April 2006

Identification of fossil leaf impressions as Cercis has been questioned based upon the presence or absence of a pulvinus at the base of the lamina (upper pulvinus). In the present study, leaves of Cercis canadensis were examined before and after abscission to explore the degradation processes that could occur prior to fossilization, and the North American record for fossil foliage of Cercis was revised accordingly. Results for C. canadensis indicate that: (1) the pulvinus consists largely of tissues with nonlignified cells (a wide cortex, a nonlignified fiber sheath, phloem, and pith) that degrade rapidly after leaf abscission, (2) the lignified xylem tissue that remains in the pulvinus after degradation is in brittle strands, (3) the pulvinus degrades at a faster rate than the lamina or the petiole, and (4) the degraded pulvinus cushion leaves a semicircular pattern on the lamina. From examination of fossils as well as extant species, we: (1) demonstrated that in fossils, the upper pulvinus can show a greater degree of degradation than the adjoining petiole or lamina tissue, suggesting the degradation of upper pulvinus tissue is similar in modern vs. fossil specimens, (2) defined numerous other laminar characters that can be used in conjunction with, or in the absence of, an upper pulvinus to confirm the presence of Cercis in the fossil record, and (3) showed from those criteria that the earliest known North American fossil leaf record for Cercis, from a specimen newly reported in the present study, is from the middle Miocene Succor Creek flora of Oregon.
Is relative pollen production or removal a good predictor of relative male fitness? an experimental exploration with a wild strawberry (Fragaria virginiana, Rosaceae)
Authors: Ashman Tia‐Lynn
Published: April 2006

Understanding plant reproduction requires knowledge of genetic contributions through pollen and seeds. Since direct genetic assessments of fitness through pollen are often intractable, reproductive ecologists use components of male fitness such as pollen production and pollen removal as surrogates for paternity. However, we know little of the strength of the relationship between these components and actual paternity. Here, I report on a study undertaken to examine the relationship of pollen production and removal with paternity in Fragaria virginiana, a wild strawberry. A morphological marker was used to track paternity in experimental arrays exposed to native pollinators. Relative pollen production proved to be a poor predictor of relative paternity in most arrays, and over all arrays there was no significant correlation between relative paternity and relative pollen production. In contrast, relative pollen removed correlated significantly and positively with proportion of seeds sired, suggesting that a plant's contribution to the pool of removed pollen is a good predictor of its male reproductive success. Deviations from expected paternity based on relative pollen removal suggest a systematic overestimation of the siring success of plants with low pollen removal. And, in at least one specific case, low pollen removal may be explained by delayed anther dehiscence, which could lower the effectiveness of the removed pollen.
Resource‐based models of competitive Interactions. I. Intraspecific Competition In Ratibida columnifera (Asteraceae)
Authors: Vargas‐Mendoza Mónica de la C. , Fowler Norma L.
Published: April 2006

We constructed and tested a series of regression models of intraspecific competition in Ratibida columnifera (Asteraceae), based on the growth and water use of individual plants. Models were constructed from a set of plants (“model”) grown without competition under three watering regimes. Each model was then tested on another set of plants (“test”) grown, singly or in pairs, under two watering regimes, one of them different than those of the “model” plants. Both sets of plants were grown simultaneously. Models that used only estimates of plant dry mass (ISON [interval by interval size only], and SON [size only]) were outperformed (i.e., the difference between predicted values of final dry mass and their true values were larger on average) by models that incorporated direct measures of water uptake and usage (ISAW [interval by interval size and water], WON [water only], SAW [size and water]). Harvest biomass predictions given by these three last models deviated from values of true biomass by an average of only 6.1%.
Phylogeny of Podocarpaceae: comparison of Evidence from Morphology and 18s rDNA
Authors: Kelch Dean G.
Published: April 2006

Maximum parsimony analyses of the genera of Podocarpaceae were conducted using sequence data from 18S ribosomal DNA. Trees from sequence, morphological, and combined data differ in taxon arrangement, but are similar in that Podocarpus sensu lato and Dacrydium s.l. are unnatural, while Podocarpaceae (including Phyllocladus) are monophyletic. The clade Microcachrys + Microstrobos is recognized in all analyses, but its placement differs, i.e., nested among other scale‐leaved taxa in the morphological analysis, but associated with Nageia and other tropical genera in the sequence analyses. Trees from combined data reflect this ambiguity. Podocarpus sensu stricto is paraphyletic according to most trees. Inferences of plesiomorphic character states within the family are largely consistent between analyses and support the view that prototypical podocarps had bifacial leaves, cones with several fertile cone scales, and large epimatia (cone scales) that covered the inverted ovules.
Phylogenetic relationships in Asarum (Aristolochiaceae) based on morphology and ITS sequences
Authors: Kelly Lawrence M.
Published: April 2006

A cladistic analysis of Asarum was conducted using data from morphology and nuclear ribosomal internal transcribed spacer sequences (ITS) to examine the relationships among several groups of taxa that have often been treated as segregate genera. Morphological and molecular data were analyzed simultaneously for a set of 36 terminals representing the taxonomic, morphological, and geographic diversity of the genus. The two data sources are generally congruent and together provide more resolution than either by itself. The data support two main clades in the genus: an Asarum sensu stricto clade and an Asiasarum + Hexastylis + Heterotropa clade. The former consists of ∼17 species and is distributed through North America, Europe, and Asia. Within this group, the North American species are monophyletic and derived from within the paraphyletic Asiatic species group. The Asiasarum + Hexastylis + Heterotropa clade consists of two Asiatic segregates and the North American segregate, Hexastylis. Resolution within this group supports both the monophyly of Heterotropa and a sister group relationship of Asiasarum to Hexastylis + Heterotropa. Hexastylis is paraphyletic and occurs as two separate clades on the tree; one of these is sister to Heterotropa and the other is sister to the latter plus Heterotropa. The phylogenetic data provide several clues about the biogeographic history of Asarum and suggest that: (1) the genus likely originated in Asia and underwent substantial diversification prior to colonizing North America; and (2) Asarum in North America represents at least two historically distinct groups that likely achieved their North American distributions at different times. The results of these analyses support recognition of two subgenera, Asarum and Heterotropa, each with two sections: Asarum and Geotaenium of the former, and Asiasarum and Heterotropa of the latter. Asarum sect. Ceratasarum (Hexastylis) is here treated as a synonym of Asarum sect. Heterotropa. A taxonomic conspectus of the genus is provided, and the combination Asarum sect. Geotaenium (F. Maek.) L. Kelly is made in accordance with the revised circumscription of taxa.
Reproductive biology of two dominant prairie grasses (Andropogon gerardii and sorghastrum nutans, Poaceae): male‐biased sex allocation in wind‐pollinated plants?
Authors: McKone Mark J. , Lund Christopher P. , O'Brien Joshua M.
Published: April 2006

It has been proposed that some wind‐pollinated plants have the necessary conditions for an optimal sex allocation that is male biased, though there are few data that address this prediction. We determined that two prairie grass species (Andropogon gerardii and Sorghastrum nutans) had reproductive characteristics that theoretically would result in a male‐biased allocation: both species were self‐incompatible and neither species had increased seed set after supplemental hand pollination. The relative allocation to pollen and seed production was measured in terms of biomass, energy, nitrogen, phosphorus, potassium, magnesium, and calcium. Sex allocation in A. gerardii was significantly male biased (from 60 to 89% male) when measured in currencies of biomass, energy, potassium, and calcium; there was no significant bias in the sex allocation (from 49 to 57% male) when measured in currencies of nitrogen, phosphorus, and magnesium. sex allocation in S. nutans was significantly male biased (from 69 to 81% male) for all currencies except phosphorus (61% male). This is the first evidence for male‐biased sex allocation in any plant or animal hermaphrodite. Though the necessary conditions may be uncommon, male‐biased allocation may be found in other species with similar reproductive biology.
OSMUNDA (OSMUNDACEAE) FROM THE TRIASSIC OF Antarctica: an example of evolutionary stasis
Authors: Phipps Carlie J. , Taylor Thomas N. , Taylor Edith L. , Cúneo N. Rubén , Boucher Lisa D. , Yao Xuanli
Published: April 2006

Compressed specimens of the fern Osmunda are described from the Triassic of the Allan Hills, Antarctica. The specimens consist of a once pinnate, deeply pinnatifid fertile frond as well as several sterile specimens. Six pinnae are present on the partial fertile rachis, with two sterile pinnae above four fertile pinnae. Both sterile and fertile specimens are virtually identical to the modern species Osmunda claytoniana. Entire fronds are fragmentary; the longest is 21 cm in length. Sterile pinnae are alternate and deeply pinnatifid, with slightly toothed pinnules and dichotomous venation. Fertile pinnae are 1–1.3 cm long, once pinnate, and lack vegetative lamina. Sporangia are clustered, each 300–375 µm in diameter, and possess a transverse annulus 6–8 cells long; dehiscence is by a vertical slit. Fronds arise from a rhizome 4 cm long by 1 cm wide; two croziers are present on the rhizome. Two frond segments up to 6 cm long and three deeply pinnatifid pinnae are present on the uppermost part of one rachis. Pinnules are ~4 mm long and 2–3 mm wide. The presence of this Osmunda species in the Triassic demonstrates stasis of frond morphology, both fertile and vegetative, for the genus.
Molecular systematics of Apiaceae subfamily Apioideae: phylogenetic analyses of nuclear ribosomal DNA internal transcribed spacer and Plastid rpoC1 intron sequences
Authors: Downie Stephen R. , Ramanath Seemanti , Katz‐Downie Deborah S. , Llanas Esmeralda
Published: April 2006

Evolutionary relationships among representatives of Apiaceae (Umbelliferae) subfamily Apioideae have been inferred from phylogenetic analyses of nuclear ribosomal DNA internal transcribed spacer (ITS 1 and ITS 2) and plastid rpoC1 intron sequences. High levels of nucleotide sequence variation preclude the use of the ITS region for examining relationships across subfamilial boundaries in Apiaceae, whereas the rpoC1 intron is more suitably conserved for family‐wide phylogenetic study but is too conserved for examining relationships among closely related taxa. In total, 126 ITS sequences from subfamily Apioideae and 100 rpoC1 intron sequences from Apiaceae (all three subfamilies) and outgroups Araliaceae and Pittosporaceae were examined. Phylogenies estimated using parsimony, neighbor‐joining, and maximum likelihood methods reveal that: (1) Apiaceae subfamily Apioideae is monophyletic and is sister group to Apiaceae subfamily Saniculoideae; (2) Apiaceae subfamily Hydrocotyloideae is not monophyletic, with some members strongly allied to Araliaceae and others to Apioideae + Saniculoideae; and (3) Apiaceae subfamily Apioideae comprises several well‐supported subclades, but none of these coincide with previously recognized tribal divisions based largely on morphological and anatomical characters of the fruit. Four major clades in Apioideae are provisionally recognized and provide the framework for future lower level phylogenetic analyses. A putative secondary structure model of the Daucus carota (carrot) rpoC1 group II intron is presented. Of its six major structural domains, domains II and III are the most, and domains V and VI the least, variable.
Anatomy and distribution of foliar idioblasts in Scrophularia and Verbascum (Scrophulariaceae)
Authors: Lersten Nels R. , Curtis John D.
Published: April 2006

Internal secretory structures have rarely been reported from Scrophulariaceae, and foliar idioblasts only once before, in 1887. Presented here are the first unambiguous descriptions of subepidermal foliar idioblasts in the family, from Scrophularia and Verbascum, genera regarded as closely allied on other grounds. Leaf samples from 183 mostly herbarium specimens (128 species, with 55 replicates) were cleared and stained, which revealed idioblasts in 62 (69.7%) of 89 Scrophularia species and 13 (33.3%) of 39 Verbascum species. We then chose 14 representative species to examine by resin sectioning and scanning electron microscopy. Idioblasts occurred both adaxially and abaxially. Most were conspicuous, in some species penetrating to vasculature level. Idioblasts had a thin primary wall and were empty at maturity. Verbascum and Scrophularia species with and without idioblasts were scattered among the subgeneric taxa without taxonomic clustering; likewise, both types occurred in approximately proportionate numbers throughout the geographic range, except that 14 of 15 North American Scrophularia species had idioblasts. Petals of two species had abundant idioblasts. The 1887 report illustrated a huge idioblast in S. deserti and we also found the largest in either genus in this species. We also noted trichome and stomata types and report that paraveinal mesophyll and foliar endodermis with casparian strip were both absent.
Conservation of microsatellites among tropical trees (Leguminosae)
Authors: Dayanandan S. , Bawa Kamaljit S. , Kesseli Rick
Published: April 2006

Although microsatellites or simple sequence repeats (SSRs) have become a popular tool in genetic mapping and gene flow studies, their utility is limited due to paucity of information about DNA sequences in plants. We tested the utility of microsatellite markers characterized for the tropical tree Pithecellobium elegans as a genetic tool for related species. The results indicate that SSR loci are conserved among closely related species, and SSR primers developed for P. elegans could be successfully used as a genetic tool in several species of the tribe Ingeae. This study indicates that there is high potential for the transfer of SSR markers among closely related taxa, circumventing laborious cloning and screening procedures involved in characterizing SSR loci for many species.
Effects of bison and cattle on growth, reproduction, and abundances of five tallgrass prairie forbs
Authors: Damhoureyeh Said A. , Hartnett David C.
Published: April 2006

Forb populations were sampled on Kansas tallgrass prairie to examine the effects of native (bison) and domestic (cattle) ungulates on plant growth, reproduction, and species abundances. Five locally and regionally abundant native tallgrass prairie perennials, Baptisia bracteata, Oenothera speciosa, Vernonia baldwinii, Solidago missouriensis, and Salvia azurea, were selected for study. Replicate watershed‐level treatments included three grazing regimes (ungrazed, grazed by cattle, and grazed by bison), and two spring fire frequencies (annually burned and burned at 4‐yr intervals). The results show that forb responses to ungulates in tallgrass prairie are complex and vary significantly among plant species, ungulate species, fire regimes, and plant life history stages. Some forbs (e.g., B. bracteata, O. speciosa, and V. baldwinii) increased in growth and reproduction in grazed sites, indicating competitive release in response to selective grazing of the dominant warm‐season matrix grasses. Forbs that reduced performance in grazed sites are likely negatively affected by disturbances generated by ungulate nongrazing activities, because none of the forbs studied were directly consumed by bison or cattle. Large grazers had no detectable effect on the frequency of plant damage by other herbivores or pathogens. Significant effects of grazers on patterns of flowering and seed production were not congruent with their effects on population densities, indicating that variation in sexual reproduction plays a minor role in regulating local population abundances. Furthermore, the native and domestic ungulates differ significantly in their effects on forb growth and reproduction.
Variation in magnesium and nitrogen content in seeds of antelope bitterbrush (Purshia tridentata, Rosaceae)
Authors: Krannitz Pam G.
Published: April 2006

One‐hundred and sixty‐three seeds from 38 shrubs of antelope bitterbrush (Purshia tridentata) from four different sites were individually analyzed for N and Mg content. Seed nutrient content has previously been shown to affect seedling growth, competitive ability, and adult biomass and seed production, though estimations of nutrient concentration in seeds have always been based on bulk samples of more than one seed. The results from antelope bitterbrush show that individual seeds vary in N and Mg content (coefficient of variation = 15.9 and 10.1%, respectively), with most of the variation being attributable to seed size (over 70%). Larger seeds not only had greater absolute quantities of N and Mg, but also a greater concentration of N. Differences between seeds from the same shrub explained the second largest amount of variation (over 20%), while differences between shrubs and site of growth, though significant, accounted for much less of the variation (just over 5%). Soil N and Mg were not closely related to seed N or Mg at a site, suggesting that decisions on how much N or Mg to allocate to seeds are not entirely based on supply. Shrubs that were browsed most intensively the winter prior to seed production had seeds with higher concentrations of Mg. Differences in seed mineral content between shrubs suggest the possibility for natural selection to operate, though research to determine heritability of this character will be necessary to confirm how much of the observed variation is attributable to plasticity in seed filling.
Early floral development of Camellioideae (Theaceae)
Authors: Tsou Chih‐Hua
Published: April 2006

The early floral development of Camellioideae was studied. Two major evolutionary lineages were recognized for this subfamily. The earlier evolved lineage (Camellia, Polyspora, and Pyrenaria) has normally 11–14 perianth members, which are initiated in a continuous spiral and are differentiated into sepals and petals at late floral development, and numerous stamens initiated individually and centrifugally on the whole androecial region. The later derived lineage (Franklinia, Hartia, Schima, and Stewartia) has five sepals and five petals arranged in two whorls, and numerous individual stamens originating centrifugally from the five petal‐opposed zones. Hartia‐Stewartia and Franklinia‐Schima further diverged as two branches — the former is characterized by having androecial fascicles and axile‐basal placentation. The androecial fascicle is considered to be derived within this subfamily. The latter exhibits a higher degree of carpellary congenital fusion and axile‐central placentaion, and as a whole, is concluded to be the most advanced group in the Camellioideae. A taxonomic treatment of the Camellioideae at the tribal level is also proposed.
Effects of competition and litter on a carnivorous plant,Drosera capillaris(Droseraceae)
Authors: Brewer J. Stephen
Published: April 2006

Although carnivorous plants are widely recognized as being generally restricted to open habitats, tests of the effects of competition on individual performance are extremely rare. In this study, I examined the effects of the removal of herbaceous and shrub canopies on seedling density and growth, survival, and reproduction of phytometers of a small insectivorous plant,Drosera capillaris(pink sundew). I also examined the distribution of this species in relation to the occurrence of woody species in a frequently burned wet savanna in southeastern Mississippi. Killing plants and removing dead biomass increased seedling density in both open areas and shrub thickets. The removal of dead biomass following herbicide application was critical to increasing densities of seedlings. Killing plants with herbicide without also clearing residual litter and standing dead was not sufficient to increase seedling densities in shrub thickets. Although the removal of the groundcover canopy strongly influenced the density of seedlings, it had very little effect on survival, growth, and reproduction of small phytometers during a single growing season. Survival of phytometers was greater in open areas than in shrub thickets, regardless of whether the groundcover canopy was removed. Densities of both seedlings and adults were greater in open areas away from shrub thickets than beneath the woody canopies of thickets and were negatively correlated with the leaf area index of groundcover vegetation. Results of this study show that the establishment of this carnivorous plant species is limited in part by the effects of litter on seedling density in both open areas and shrub thickets.
The effects of developmental stage and source leaf position on integration and sectorial patterns of carbohydrate movement in an annual plant, Perilla frutescens (Lamiaceae)
Authors: Preston Katherine A.
Published: April 2006

A well‐integrated plant shows extensive carbohydrate translocation through the plant body. Even in highly integrated plants, however, translocation patterns will be sectorial if vascular tissue restricts carbon movement to sectors along stems. Both integration and sectorial translocation patterns are sensitive to plant architecture and thus may change as a plant develops. These patterns should vary also with the position of the source leaf because leaves at each node are unique in age and vascular relationship to the rest of the plant. I measured the effects of developmental stage and location of the source leaf on integration and sectoriality in an annual plant, Perilla frutescens, by labeling plants with 14C at one of three leaves and four developmental stages. Stage and source leaf affected both integration and sectoriality. Most notably, integration declined and sectoriality increased during seed fill, when resource demand at each node was high. Furthermore, translocation was least extensive from the leaf supporting the largest number of seeds on its axillary branch. These results suggest that plants are not homogeneous collections of subunits; rather, the role of each leaf in a plant's carbon budget is a function of its age and location on the plant.
Estimation of temperature and precipitation from morphological characters of dicotyledonous leaves
Authors: Wiemann Michael C. , Manchester Steven R. , Dilcher David L. , Hinojosa Luis Felipe , Wheeler Elisabeth A.
Published: April 2006

The utility of regression and correspondence models for deducing climate from leaf physiognomy was evaluated by the comparative application of different predictive models to the same three leaf assemblages. Mean annual temperature (MAT), mean annual precipitation (MAP), and growing season precipitation (GSP) were estimated from the morphological characteristics of samples of living leaves from two extant forests and an assemblage of fossil leaves. The extant forests are located near Gainesville, Florida, and in the Florida Keys; the fossils were collected from the Eocene Clarno Nut Beds, Oregon. Simple linear regression (SLR), multiple linear regression (MLR), and canonical correspondence analysis (CCA) were used to estimate temperature and precipitation. The SLR models used only the percentage of species having entire leaf margins as a predictor for MAT and leaf size as a predictor for MAP. The MLR models used from two to six leaf characters as predictors, and the CCA used 31 characters. In comparisons between actual and predicted values for the extant forests, errors in prediction of MAT were 0.6°–5.7°C, and errors in prediction of precipitation were 6–89 cm (=6–66%). At the Gainesville site, seven models underestimated MAT and only one overestimated it, whereas at the Keys site, all eight models overestimated MAT. Precipitation was overestimated by all four models at Gainesville, and by three of them at the Keys. The MAT estimates from the Clarno leaf assemblage ranged from 14.3° to 18.8°C, and the precipitation estimates from 227 to 363 cm for MAP and from 195 to 295 cm for GSP.
Intraspecific variation and phylogeographic patterns of Fagus crenata (Fagaceae) mitochondrial DNA
Authors: Tomaru Nobuhiro , Takahashi Mizuki , Tsumura Yoshihiko , Takahashi Makoto , Ohba Kihachiro
Published: April 2006

Mitochondrial (mt) DNA variation in Japanese beech, Fagus crenata (Fagaceae), was studied in 17 populations distributed throughout the species’ range. Total genomic DNA of samples from single trees representing each of 12 populations were digested with 18 restriction enzymes and hybridized with three probes containing coxI, coxIII, and atpA gene sequences. Thirty‐four of the 54 enzyme/probe combinations showed polymorphisms and all the individuals were subsequently analyzed with six combinations of three probes and two enzymes. Restriction fragment length polymorphisms were evident around all three genes, allowing the identification of eight distinct haplotypes. Haplotype diversity within the populations was found to be very low (HS = 0.031), but population differentiation to be much higher (GST = 0.963). The mtDNA variation was strikingly different from allozyme variation (HS = 0.209; GST = 0.039). Gene flow for maternally inherited mtDNA should be restricted to seed dispersal while nuclear gene flow occurs by both seed and pollen dispersal. Therefore, the difference in the variation between mtDNA and allozymes may be largely a result of the much higher rate of gene flow associated with pollen dispersal than with seed dispersal. The mtDNA variation displayed strong geographic structure, which may reflect the species’ distribution in the last glacial maximum and subsequent colonization, and probably also reflects intraspecific phylogeography of the species.
Anatomically preserved leaves of the conifer notophytum krauselii (Podocarpaceae) from the Triassic of Antarctica
Authors: Axsmith Brian J. , Taylor Thomas N. , Taylor Edith L.
Published: April 2006

Permineralized leaves of the Triassic podocarpaceous conifer Notophytum krauselii are described from the Fremouw Formation of Antarctica. The leaves are elongate and apetiolate with 8–12 parallel veins. The adaxial epidermis consists of rows of rectangular to pentagonal cells; the abaxial epidermis is papillate. Longitudinally oriented stomata occur on both surfaces. An adaxial palisade layer is present and auxiliary sclereids are common in the mesophyll. The vascular bundles have a weakly defined sheath and are flanked by transfusion tracheids. Bundles in the basipetal area of the leaf are capped by sclerotic tissue and subtended by resin canals. These leaves are superficially similar to those of the extant podocarp genus Nageia, but probably represent a distinct acquisition of this leaf type within the Podocarpaceae. Notophytum leaves are similar to the common compression fossil Heidiphyllum elongatum and may be closely related or even conspecific. Evidence from Antarctica suggests that Heidiphyllum and the seed cone Telemachus were produced by the same plant, and may be closely related to several other early Mesozoic conifers with multiveined leaves.
Nonrandom mating and sexual selection in a desert mustard: an experimental approach
Authors: Mitchell Randall J. , Marshall Diane L.
Published: April 2006

We report on an experiment to explore the importance of pollinator behavior and postpollination events within flowers in generating nonrandom mating in the desert perennial Lesquerella fendleri (Brassicaceae). In this experiment, we crossed four plants with each other in all combinations. We performed these crosses in three different ways, which varied the opportunity for nonrandom mating: single‐donor hand pollinations, mixed hand pollinations, and field pollinations. Number of seeds sired by each donor following single‐donor pollinations differed only slightly (though significantly) from random, indicating little variation in siring ability. However, we found more dramatic (and significant) departures from random mating for mixed hand pollinations. In the field we found even more nonrandomness, with some donors siring >71% of seeds on some maternal plants, despite equal opportunity to father seeds. The rank ordering of donors was consistent across the four females and across treatments, indicating that there was concordant nonrandom mating, a requirement for sexual selection. The most successful donor in all treatments also had the greatest pollen production per flower, and this trait may therefore be an important cause of the observed patterns. We infer that pollinator behavior and postpollination processes both contribute to the nonrandom mating observed in the field, and discuss the advantages of this new experimental approach.