Pityopsis Graminifolia Research Articles

Underground carbohydrate stores and storage organs in fire-maintained longleaf pine savannas in Florida, USA.

Many perennial herbaceous plants develop underground storage organs (USOs) that store carbohydrates, water, and minerals. The resprouting ability of plants is influenced by the availability of these materials and by the type of underground organ and number of viable buds. In this study, we illustrate the diversity of longleaf pine savanna species and their nonstructural carbohydrate (NSC) pools and concentrations. We also determined whether NSC concentrations by USO are good predictors of NSC pools in species with different types of underground structures. We excavated in their entirety 1-4 individuals of each of 100 ground-layer pine savanna species, classified their USO types, and measured their NSC concentrations and NSC pools. The NSC concentrations in underground organs varied widely among the 100 species sampled. Surprisingly, the fibrous roots of Pityopsis graminifolia stored higher concentrations of NSCs than many species with USOs. The relationship between NSC concentrations and NSC pools was strong after controlling for underground biomass. Our results revealed the high diversity of underground organs in pine savannas. It also showed that NSC concentrations in species with USOs reach high levels. Predictions of NSC pool sizes from NSC concentrations are interpretable, when corrections for underground biomass are considered. Research on underground organs would benefit from inclusion of morphological-anatomical analyses and phylogenetic controls to promote use of the data in broad-scale analyses.

Influence of selection systems and shelterwood methods on understory plant communities of longleaf pine forests in flatwoods and uplands

Although longleaf pine (Pinus palustris Mill.) forests have mostly been managed with even-aged methods, interest has been rising in uneven-aged systems, as a means of achieving a broader range of stewardship objectives. Selection silviculture has been practiced on a limited scale in longleaf pine, but difficulty of using traditional approaches and absence of an evaluation across a range of site types has left managers in doubt about its suitability. This study was conducted to quantify the effects on understory plant communities of applying single-tree selection, group selection, irregular shelterwood and uniform shelterwood in longleaf pine forests on flatwoods and uplands of the southeastern United States. Wiregrass (Aristida beyrichiana Trin. & Rupr.) and numerous other graminoids are highly desirable understory species, because they facilitate the essential ecological process of recurrent surface fire that sustains longleaf pine ecosystems. Forbs such as partridge pea (Chamaecrista fasciculata (Michx.) Greene) and low shrubs such as gopherapple (Licania michauxii Prance), blueberries (Vaccinium spp. L.) and huckleberries (Gaylussacia spp. Kunth) are also desirable as components of good wildlife habitat. Selection treatments reduced stand basal area to ∼11.5m2ha−1 and shelterwood treatments left a basal area of ∼5.8m2ha−1. While higher levels of logging traffic from shelterwood treatment caused a significant decline in saw-palmetto (Serenoa repens W. Bartram) cover and increases in wiregrass at the flatwoods site, on the upland site it resulted in a sharp decline in wiregrass and silverthread goldaster (Pityopsis graminifolia (Michx.) Nutt.). Absence of prescribed fire during the post-treatment years led to progressive increases for shrub cover broadly across the flatwoods. Group selection caused modest understory change in flatwoods (temporary decrease in shrubs and increase in wiregrass), but resulted in a doubling of understory plant cover on uplands, with significant increases for hardwood tree seedlings, shrubs, vines, wiregrass, forbs and ferns. Single-tree selection caused no lasting impact on saw-palmetto, a decline in gallberry (Ilex glabra (L.) A. Gray) and increase in wiregrass in flatwoods and was related on uplands to increases in oak (Quercus spp. L.), dangleberry (Gaylusaccia frondosa (L.) Torr. & A. Gray ex. Torr.), broomsedge bluestem (Andropogon virginicus L.) and several forbs. Single-tree selection produced less change in the forest than group selection, which caused less alteration than shelterwood treatment. Selection silviculture appears to be a lower risk option for guiding longleaf pine forests along a trajectory of gradual improvement, with adjustments provided by frequent surface fires and periodic tree harvest. Long-term observation is needed to verify that selection can sustain diverse plant communities on sites characterized by differing environments.

Land‐use legacies and present fire regimes interact to mediate herbivory by altering the neighboring plant community

Past and present human activities, such as historic agriculture and fire suppression, are widespread and can create depauperate plant communities. Although many studies show that herbivory on focal plants depends on the density of herbivores or the composition of the surrounding plant community, it is unclear whether anthropogenic changes to plant communities alter herbivory. We tested the hypothesis that human activities that alter the plant community lead to subsequent changes in herbivory. At 20 sites distributed across 80 300 hectares, we conducted a field experiment that manipulated insect herbivore access (full exclosures and pseudo‐exclosures) to four focal plant species in longleaf pine woodlands with different land‐use histories (post‐agricultural sites or non‐agricultural sites) and degrees of fire frequency (frequent and infrequent). Plant cover, particularly herbaceous cover, was lower in post‐agricultural and fire suppressed woodlands. Density of the dominant insect herbivore at our site (grasshoppers) was positively related to plant cover. Herbivore access reduced biomass of the palatable forb Solidago odora in frequently burned post‐agricultural sites and in infrequently burned non‐agricultural woodlands and increased mortality of another forb (Pityopsis graminifolia), but did not affect two other less palatable species (Schizachyrium scoparium and Tephrosia virginiana). Herbivory on S. odora exhibited a hump‐shaped response to plant cover, with low herbivory at low and high levels of plant cover. Herbivore density had a weak negative effect on herbivory. These findings suggest that changes in plant cover related to past and present human activities can modify damage rates on focal S. odora plants by altering grasshopper foraging behavior rather than by altering local grasshopper density. The resulting changes in herbivory may have the potential to limit natural recovery or restoration efforts by reducing the establishment or performance of palatable plant species.

Characterization of 12 polymorphic microsatellite loci of Pityopsis graminifolia var. latifolia

Pityopsis graminifolia (Michx.) Small var. latifolia (Fern.) Semple is an herbaceous perennial that grows in close proximity to the federally endangered species P. ruthii (Small) Small. Twelve polymorphic microsatellite loci were identified from 87 samples of P. graminifolia var. latifolia and additionally characterized with P. ruthii and P. falcata samples. Alleles per locus ranged from 4 to 21. Expected heterozygosity ranged from 0.077 to 0.106 and Shannon’s Information Index ranged from 0.135 to 0.244. These microsatellite loci can be used to study genetic diversity and population diversity of P. graminifolia var. latifolia and its relationship to other Pityopsis species.

Ornamental Landscape Performance of Native and Nonnative Grasses under Low-input Conditions

Full sun trial gardens (full sun) were established at Leon County (LC) and Santa Rosa County (SRC), Florida, to evaluate the effect of site on horticultural performance traits pertinent to landscape use (long-term growth, flowering, vigor, overall quality, and survival) of native and nonnative warm season grasses when grown under low-input landscape conditions over a 3-year period. The gardens contained landscape fabric- (LC) or plastic (SRC)-covered rows, with the synthetic mulch at each site covered by 4 inches of hardwood chip mulch. Fifteen native and eight nonnative grass species, and cultivars were evaluated as were the two grass-like species black flowering sedge (Carex nigra) and narrowleaf silkgrass (Pityopsis graminifolia), a native dicot with grass-like foliage. Many of the native species were derived from seeds or plants collected from naturally occurring populations in Florida, and other species or cultivars were obtained from commercial sources. Based on quality ratings and survival, a majority of the species and cultivars were rated as at least being marginally acceptable for 2 years or more, but only six species and cultivars were rated as excellent or good over all 3 years. Four of these six species were native, with 100% survival at both sites occurring only for purpletop tridens (Tridens flavus). The other three native species, gulf hairawn muhly, (Muhlenbergia capillaris var. filipes), ‘Alamo’ switchgrass (Panicum virgatum), and indian woodoats (Chasmanthium latifolium) had high rates of survival. Porcupine grass (Miscanthus sinensis ‘Strictus’) and ‘Cabaret’ silver grass (M. sinensis ssp. condensatus) were the only two nonnative species demonstrating potential for long-term performance in a low-input landscape at both sites. Three of the four cultivars of miscanthus (Miscanthus spp.) survived the entire evaluation period in SRC, while two cultivars suffered losses only in LC, demonstrating the importance of site effects on the long-term performance of individual species or cultivars of grasses. Chalky bluestem (Andropogon capillipes) (Orange County, FL), sand lovegrass (Eragrostis trichoides), giant silver grass (Miscanthus ×giganteus), and bamboo muhly (Muhlenbergia dumosa) each survived 3 years at one site but only 1 year at the other site. Pineland threeawn (wiregrass) (Aristida stricta), ‘Red Baron’ cogon grass (japanese blood grass) (Imperata cylindrical), ‘Hameln’ fountain grass (Pennisetum alopecuroides), black flowering fountain grass (P. alopecuroides ‘Moudry’), and ‘Feesey Form’ ribbon grass (Phalaris arundinaceae) were categorized as marginal for low-input landscapes and could only be considered short-term perennials under the conditions of this test. ‘Morning Light’ silver grass (M. sinensis), coastal bluestem (Schizachyrium maritimum), and ‘Lometa’ indiangrass (Sorghastrum nutans) had good 2-year landscape performance and survived at least 2 years at both sites. Bigtop lovegrass (Eragrostis hirsuta), silver plumegrass (Saccharum alopecuroides), and lopsided indiangrass (Sorghastrum secundum) were categorized as having excellent 1-year landscape performance and have potential for short-term performance under low-input conditions. Chalky bluestem (Andropogon capillipes) (SRC), black flowering sedge, ‘Heavy Metal’ switchgrass (Panicum virgatum), and narrowleaf silkgrass were categorized as having good 1-year landscape performance.

Geographic Variation in Flowering Responses to Fire and Season of Clipping in a Fire-Adapted Plant

Identifying optimal fire regimes for a given species requires monitoring its responses to different fire regimes. This study examined the effects of fire during the lightning season and clipping in different seasons on the induction of flowering in a fire-adapted species, Pityopsis graminifolia, in two different fire-dependent ecosystems (oak forest edges in north Mississippi and longleaf pine savannas in south Mississippi). The two ecosystems differed in the frequency of lightning (higher in south Mississippi) and the timing of peak drought conditions during the lightning season (earlier in south Mississippi). Flowering was induced by prescribed fires during the lightning season in both regions. Flowering was greater in unburned controls in north Mississippi than in south Mississippi. These differences persisted in a common grass-dominated environment in the greenhouse, suggesting a genetically-based bet-hedging strategy with respect to fire-induced flowering in north Mississippi. Flowering of both varieties responded better to clipping during peak drought periods during the lightning season than to clipping treatments at other times of the year, but the causes of such seasonal differences (be they genetic or environmental) remain unresolved at this time and require further investigation.

Long-Term Population Changes of a Fire-Adapted Plant Subjected to Different Fire Seasons

Abstract Long-term studies of the responses of plant populations to fire can inform adaptive management of ecosystems. I present results of an analysis of responses of a fire-adapted plant, Pityopsis graminifolia (Michx.) Nutt. (silkgrass goldenaster), to season of fire from 2001 to 2005 in a longleaf pine (Pinus palustris P. Miller) sandhill community in north Florida. Replicated May-burned and January-burned plots had been burned biennially from 1986 to 2004. Previous work in the early 1990s showed that populations of this species benefited more from fires during the peak lightning fire season (i.e., May) than from January fires. In 2001, however, shoot densities in both treatments were substantially lower than in 1992 and remained relatively low through March 2005. Shoot densities were significantly higher in May-burned plots than in January-burned plots between 2001 and 2005. May fires significantly increased shoot densities in 2002 (relative to January fires), but did not in 2004. Shoot densities in ...

Equipment Modifications for Harvesting Fluffy Seeds

Fluffy seeds of native wildflowers are difficult to harvest using traditional equipment and methods. We modified intake and storage on a tractor-drawn leaf vacuum machine to better harvest fluffy seeded species such as aster (<i>Aster</i> L. [Asteraceae]) and narrowleaf silkgrass (<i>Pityopsis graminifolia</i> (Michx.) Nutt. [Asteraceae]). By inserting collection bags inside the vacuum and creating a vacuum hood to ride over the rows of plants, only 1 person is needed for the harvest process. The modified equipment allows us to make repeated harvests over the several-week ripening period and it removes only ripe seeds from the plants.

Host Preference of the Federally Endangered Hemiparasite Schwalbea americana L. (Scrophulariaceae)

HELTON, R. C., L. K. KIRKMAN, AND L. J. MUSSELMAN. Host preference of the federally endangered hemiparasite Schwalbea americana L. (Scrophulariaceae) J. Torrey Bot. Soc. 127:300-306. 2000.-We examined the host-preference and optimal hosts of the federally endangered hemiparasite, Schwalbea americana L. We also determined the effects of four fertilizer treatments (NO3-140ppmN, N03-280ppmN, NH4-140ppmN, and NH4280ppmN) on the formation of haustoria of S. americana to two of these host species, Panicum tenue and Pityopsis graminifolia. Results of the host preference study show that Schwalbea americana seedlings are more likely to form haustorial connections with Pityopsis graminifolia and Ilex glabra than with other common associates. We also found that size of Schwalbea americana seedlings played an important role in year to year survivorship independent of host attachment. Regardless of nitrogen form, we observed a greater rate of attachment of Schwalbea americana to Pityopsis graminifolia than to Panicum tenue. Nitrogen treatment had no effect on parasitism of Panicum tenue, although more seedlings of Schwalbea americana survived without haustoria with the NH4-280ppm treatment. Growth (leaf area and stem height) of Schwalbea americana increased with NH4-280 ppm treatment with Pityopsis graminifolia as a host. Panicum tenue had much higher nitrate reductase activity levels in the leaf tissue than Pityopsis graminifolia, and both hosts showed low levels in the root tissue. Low levels of nitrate reductase activity were found in the leaves of Schwalbea americana. Host preference of Schwalbea americana may be related to the host's ability to utilize NH4 as opposed to its ability to reduce NO3. Growth of Schwalbea americana appears to be influenced by the amount of NH4 available to the host.

Ecological land classification in the Southern Loam Hills of south Alabama

A landscape scale classification of ecosystems was undertaken on the Conecuh National Forest and Solon Dixon Forestry Education Center in south Alabama. Nine landtypes (LTs) were identified in the study area. Each LT had a unique assemblage of plant species and environmental variables. In the Pine Hills, three LTs were identified with diagnostic species including Quercus incana, Ipomoea sp., Q. stellata, Rhus copallina, Vaccinium myrsinites, and Pityopsis graminifolia. The diagnostic environmental variables were landform index, slope, B horizon depth, percent B horizon nitrogen (N), percent A horizon fine sand, and percent A horizon silt. In the Dougherty Plain, two LTs were identified with diagnostic species including Diospyros virginiana, Elephantopus tomentosus, Vaccinium corymbosum, Lechea minor, Aristida stricta, and Q. virginiana. The diagnostic environmental variables were slope and percent B horizon fine sand. In the Wet Pine Flatwoods, four LTs were identified. The diagnostic species included Diospyros virginiana, Smilax glauca, Vaccinium stamineum, Hibiscus aculeatus, Pinus elliottii, Drosera brevifolia, Clethra alnifolia, and Aristida stricta. The diagnostic environmental variables were slope, landform index, depth to mottling, percent B horizon clay, and drainage class. The vegetation of the LTs is similar to longleaf pine ecosystems throughout the southeastern Coastal Plain.

Effects of fire on sandhill herbs: nutrients, mycorrhizae, and biomass allocation

Differences in growth responses, tissue and soil inorganic nutrients, and mycorrhizal relationships of four herbaceous species were studied on burned and unburned sandhill sites in south-central Florida, USA. Three species, (Aristida stricta, Liatris tenuifolia var. laevigata, and Pityopsis graminifolia) responded positively to conditions following the burn by increased vegetative growth and flowering. The fourth species, Balduina angustifolia, is a fire-sensitive biennial and its first-year rosettes were, with an occasional exception, unable to survive or resprout following fire. Availability of all soil inorganic nutrients examined (Ca, K, Mg, and P) was low, as were total nitrogen, soil organic matter, and pH. There was a slight nutrient pulse of phosphorus into the soil following burning. For two species (Aristida and Liatris), shoot tissue concentrations of several inorganic nutrients (especially N and P) were higher on the burned site than the unburned site following burning. These differences generally dissipated over time since burning. The high concentration of tissue nutrients postburn followed by a decline on the burned site may result from rapid nutrient uptake after fire and dilution of this concentration following restoration of plant mass. Despite low levels of soil inorganic nutrients, including phosphorus, mycotrophy was absent or weakly developed among the herbaceous species examined, except for the tap-rooted Balduina angustifolia. Colonization of host plants by vesicular mycorrhizal fungi was unaffected by burning. Mycorrhizal inoculum potentials of sandhill soil were extremely low, varying seasonally from (mean +/- 1 SE) 0.3 +/- 0.2 to 3.8 +/- 0.7%.

Effects of Fire-Generated Gaps on Growth and Reproduction of Golden Aster (Pityopsis graminifolia)

only slightly greater (- 10%), however, inside gaps than outside gaps in May-burned blocks four months after the May fires. We therefore conclude that golden aster potentially performs better within fire-generated gaps than within dense vegetation dominated by wiregrass, at least in years without lightning season (May) fires. We suggest, however, that such differences between gaps and dense vegetation likely have little effect on the long term performance of golden aster in pine savannas frequently burned in May.

The Relationship between Soil Fertility and Fire-Stimulated Floral Induction in Two Populations of Grass-Leaved Golden Aster, Pityopsis graminifolia

Classic life-history theories of reproductive strategies ignore the relationship between the cost of reproduction and reproductive plasticity. In this study, I examined the extent to which two populations of a perennial plant (Pityopsis graminifolia) differed in their floral induction responses to manipulation of fire, clipping, and fertilization regimes. I also measured site differences in soil concentrations of several mineral nutrients. The two populations differed dramatically in their observed patterns of reproduction ; the north Florida population substantially increased rates of bolting in response to fire, clipping and litter removal, and nutrient addition, whereas the central Florida population did not. Soils at the central Florida site contained over three times the concentration of phosphorus compared to soils at the north Florida site. Soil phosphorus levels were significantly (albeit slightly) increased by fire at the north Florida site but not at the central Florida site. Results of a field experiment using clonal transplants indicated that the population differences in reproductive sensitivity to fire-related environmental changes were associated with genetic differences. A May fire was more effective at stimulating floral induction in clonal fragments from the north Florida site than from the central Florida site. The results of this study were consistent with the prediction that selection pressure for fire-stimulated flowering is most intense in habitats in which flowering is highly resource (e.g., phosphorus) limited. I hypothesize that fire-stimulated flowering may be a means of reducing the direct resource costs of reproduction.

Effects of Fire Season and Herbivory on Reproductive Success in a Clonal Forb, Pityopsis Graminifolia

1 In 1990 and 1992, we experimentally manipulated fire season in a longleaf pine sandhill community in north Florida, USA, and studied floral induction, bud herbivory, clone fecundity, and seedling dynamics of a perennial forb, Pityopsis graminifolia. In addition, some proximate cues of fire-related floral induction were examined using a factorial arrangement of clipping season and fertilization treatments in 1992. 2 Flowering was induced by fire. Results from the clipping/fertilization experiment showed that removal of canopy and litter is an important inductive cue associated with fire. Floral induction of clipped shoots was further influenced by soil fertility and the season during which clipping occurred. 3 Fire season influenced the proportion of shoots that bolted, the size of bolting shoots, and bud herbivory. Floral induction was greater following May and August (growing-season) fires than following January fires in 1990 and 1992. Bud herbivory by white-tailed deer was lower following growing-season fires than following January fires in 1990 and 1992. As a result, in 1992, fecundity of growing-season-burned clones was greater than that of January-burned clones, with greater shoot size leading to greater fecundity in May-burned clones than in August-burned clones. 4 Seedling emergence in early 1991, following 1990 fires, was highest in May-burned plots, intermediate in August-burned plots, and lowest in January-burned plots. Seedling survivorship through December 1992 was low in all fire season plots, but still varied in response to fire season (6% in May-burned plots, 2% in August-burned plots, and 0% in January-burned plots). Successful reproduction of 1991 cohorts following 1992 fires only occurred in May-burned plots. 5 Results from the current study suggest that reproductive success in P. graminifolia is greatest in May, intermediate in August and lowest in January. These rankings are the same as the relative likelihoods that longleaf pine savannahs will burn at these different times of the year.

Effects of Fire Season and Soil Fertility on Clonal Growth in a Pyrophilic Forb, Pityopsis graminifolia (Asteraceae)

We experimentally manipulated fire season in a longleaf pine sandhill community in north Florida in 1990 and 1992. We determined the size and demography of shoots, rhizomes, and clones of Pityopsis graminifolia from late 1990 to early 1993. In addition, we examined shoot responses to seasonal variation in canopy/litter removal and soil fertility in 1992. May fires caused a higher short-term rate of increase in shoot density than did either January fires or August fires. The combination of canopy/litter removal and mineral nutrient addition as part of the clipping experiment revealed a similar effect on shoot density in May. Fire season influenced clone structure. May fires resulted in greater numbers of shoots/clone than did January or August fires. January-burned plots had clones and rhizomes that contained larger (but fewer) shoots than did May-burned or August-burned plots. We suggest that such variation in clone structure may indicate a greater capacity of clones to grow laterally following May fires than following either January or August fires. This capacity is positively associated with the likelihood that longleaf pine savannas will be burned by lightning fires at different times during the year.

Effects of fire season and soil fertility on clonal growth in a pyrophilic forb, Pityopsis graminifolia (Asteraceae)

We experimentally manipulated fire season in a longleaf pine sandhill community in north Florida in 1990 and 1992. We determined the size and demography of shoots, rhizomes, and clones of Pityopsis graminifolia from late 1990 to early 1993. In addition, we examined shoot responses to seasonal variation in canopy/litter removal and soil fertility in 1992. May fires caused a higher short‐term rate of increase in shoot density than did either January fires or August fires. The combination of canopy/litter removal and mineral nutrient addition as part of the clipping experiment revealed a similar effect on shoot density in May. Fire season influenced clone structure. May fires resulted in greater numbers of shoots/clone than did January or August fires. January‐burned plots had clones and rhizomes that contained larger (but fewer) shoots than did May‐burned or August‐burned plots. We suggest that such variation in clone structure may indicate a greater capacity of clones to grow laterally following May fires than following either January or August fires. This capacity is positively associated with the likelihood that longleaf pine savannas will be burned by lightning fires at different times during the year.

Size-dependent allocation to sexual and vegetative reproduction in four clonal composites.

Populations of Silphium speciosum, Vernonia baldwinii, Solidago canadensis and Pityopsis graminifolia were studied to determine whether biomass allocation to sexual and vegetative reproduction and the balance between them were size-dependent and whether interpopulation differences in allocation patterns could be predicted from differences in population size distributions. All four species showed strong linear relationships between inflorescence mass and vegetative mass with negative y-intercepts. As a result, sexual reproductive effort (SRE) was a monotonically increasing function of ramet size. Genet size was a poor predictor of SRE. In each species, the regression parameters of these relationships differed significantly between burned and unburned habitats indicating size-independent interpopulation differences in patterns of reproductive effort as well as sizedependent effects. Interpopulation variation in vegetative reproductive effort (VRE) was greater than variation in SRE, but neither VRE nor the pattern of partitioning of VRE among daughter rhizomes showed significant relationships to plant size.

Gopher Tortoise (Gopherus polyphemus) Effects on Soils and Vegetation in a Florida Sandhill Community

Burrowing and mound-building activities of gopher tortoises generated significant environmental heterogeneity in an oak-pine sandhill forest in Florida. Mounds were characterized by lower soil nutrient and organic matter concentrations, higher light intensities and greater diurnal temperature fluctuations than adjacent undisturbed areas. Temperatures during prescribed spring fires were significantly lower on mounds and near burrow openings relative to the surrounding undisturbed vegetation. Changes in plant species composition and relative abundances between recently abandoned mounds, old mounds and undisturbed areas indicated that mounds undergo microsuccession and contribute toward increased plant species diversity in the forest understory. Old mounds had the highest species richness per unit area. Mound size had no effect on plant population dynamics or community structure. Gopher tortoise disturbances increased the frequency of recruitment by seed relative to vegetative reproduction in the common rhizomatous forb, Pityopsis graminifolia.

EFFECTS OF FIRE ON CLONAL GROWTH AND DYNAMICS OF PITYOPSIS GRAMINIFOLIA (ASTERACEAE)

The rhizomatous perennial Pityopsis graminifolia was studied in a Florida sandhill community in an annually burned site, a periodically burned site, and a site that has been protected from fire since 1965. These different fire regimes significantly affected the demography and life histories of both plants and plant parts in this clonal species. Fires resulted in reductions in ramet biomass and height, and an increase in the (root + rhizome)/shoot biomass ratio. Burning also decreased the total number of flower heads and new rhizomes produced per ramet. However, the survivorship of initiated rhizomes was greater in burned sites and resulted in a larger number of established daughter ramets per clone. As a result, in burned sites there was a shift in clone structure toward larger numbers of smaller ramets, but there were no significant reductions in seed or rhizome production on a per genet basis.The results showed that the responses to fire in P. graminifolia are different when measured at the genet vs. ramet level and that the effects of fire on clones can be explained by demographic responses of plant parts. Population regeneration in the study sites was dependent on successful clonal ramet production because no seedling recruitment was observed. This suggests that disturbances other than fire are important for new genet recruitment in these clonal populations.

Morphological, anatomical, habit, and habitat differences among the goldenaster genera Chrysopsis, Heterotheca, and Pityopsis (Compositae–Astereae)

The leaf morphology and anatomy, fruit morphology, growth forms, and distribution patterns of species of the three goldenaster genera Chrysopsis, Heterotheca, and Pityopsis were analyzed and compared, with the conclusion that they should be treated as three distinct genera. The species of Chrysopsis were characterized by flexible flagelliform hairs. Heterotheca had stiff uniseriate, osteolate hairs. Pityopsis had long filamentous hairs that adhered to each other in a reticulate pattern. Chrysopsis and Heterotheca had similar leaf anatomy and compressed-obconic fruits (except for the epappose ray floret fruits of sect. Heterotheca). Pityopsis had distinctive leaf anatomy and morphology and had fusiform fruits. Chrysopsis included one annual plus biennial to weakly perennial and true perennial species distributed primarily in Florida. Pityopsis included only herbaceous perennials with fibrous roots distributed throughout the southeastern United States for the most part. Heterotheca included mostly herbaceous perennials with taproots distributed throughout western North America from Canada to Mexico. Some members of sect. Heterotheca were annuals occurring in the southern United States. A key to the genera and sections of the goldenasters has been included. The following new nomenclatural combinations have been made: Chrysopsis gossypina ssp. cruiseana, C. gossypina ssp. hyssopifolia, C. gossypina, f. trichophylla, Heterotheca camphorata, Pityopsis adenolepsis, and Pityopsis graminifolia var. microcephala.