Three oak species dominate the mature montane cloud forests in the Talamanca mountain range, Costa Rica. These oak species exist at different elevations and encounter increasing soil and atmospheric stress conditions as elevation increases along a gradient (2,000–3,200 m). We compared acorn characteristics, seed germination, seedling morphology, and leaf morphology of these three oak species to determine if these traits varied along this elevation gradient. Seeds were measured, weighed, and examined for viability and germination. Seeds were planted in a common garden at 2,700 m to evaluate seedling development, morphology, and growth. We found that seeds had high water content and germination patterns typical of the recalcitrant syndrome. Quercus costaricensis acorns were bigger and had higher viability and seed germination than acorns and seeds of Quercus salicifolia and Quercus bumelioides. However, seeds from the smaller acorns of Q. salicifolia and Q. bumelioides were not less prone to germinate than Q. costaricensis. Germination was of the phanerocotylar-semihypogeal-reserve type, consistent with the temperate origin of the genus. The developing seedlings produced a leafy crown and a vigorous adventitious root system soon after germination. Together, these new organs allow seedlings to substitute or complement the resources provided by the fleshy cotyledons. Leaves of Q. costaricensis seedlings (from the highest elevation) were smaller, darker, and thicker than those of Q. bumelioides and Q. salicifolia. However, there were no differences in leaf mass per area among seedlings of different species. We discuss the importance of interspecific differences in seedling growth resulting from seed size differences and environmental heterogeneity for niche segregation and the observed distribution of Q. salicifolia, Q. bumelioides, and Q. costaricensis along the elevation gradient.

Although it is yet to be conclusively established, floral features of many legumes of the mimosoid clade suggest the existence of a highly wasteful late-acting form of genetic self-incompatibility. We evaluated the role this may have played in the evolution of aggregated pollen, restricted stigmas, and polycarpelly in these plants by first investigating the reproductive biology of two species from the southeastern United States: Mimosa microphylla and Albizia julibrissin. Insights gained from detailed study of their reproductive biology informed a wider, critical review of reproductive characters in other members of the clade. Descriptions of the flowers and inflorescences of the two southeastern U.S. species fail to define clearly the functional situation, including that both species are andromonoecious. Pollen of M. microphylla is released as tetrads, whereas polyads of 16 pollen grains characterize A. julibrissin. Diameters of the cup-like stigmas are constrained so that typically only one or a few tetrads or one polyad will fit. These features are consistent with a syndrome involving, in its fullest manifestation, low fruit set, restriction of stigmatic surfaces, pollen aggregation, reduction of ovule number, and polycarpelly. We interpret all of these unusual features as adaptations to circumvent a highly wasteful (of pollen and ovules) form of late-acting self-incompatibility in which rejection of self-pollen occurs in the ovary. These adaptations reduce the likelihood of a mixed load of self- and cross-pollen being delivered. Enhanced efficiency of pollen transfer may also contribute to the evolution of aggregated pollen, but this explanation fails to account for the other unusual features of this syndrome.

The Linnaean names Malva abutiloides, Sida alba, Sida americana, and Sida triquetra are investigated. Sida alba is a nomen nudum and not validly published according to the Art. 38.1 of the International Code of Nomenclature for algae, fungi, and plants. Sida triquetra is a superfluous and illegitimate name, replacement of the legitimate Sida trisulcata by Jacquin. The name S. americana is lectotypified by a specimen kept at LINN (No. 866.25). For nomenclatural purposes, the names Abutilon dentatum (= A. abutiloides), Albutilon ramosissimum (= S. trisulcata), Sida tricuspidata (= A. abutiloides), and Sida lignosa (= A. abutiloides) were also studied. These four names are lectotypified by specimens preserved at US (A. dentatum), PR (A. ramosissimum), and MA (S. tricuspidata and S. lignosa).

Soil and whole plant samples were collected from two natural populations of Appalachian black cohosh (Actaea racemose L.) to assess soil-plant-microbe interactions and determine seasonal mineral acquisition by the species. A. racemosa is one among medicinal forest plants subject to excessive harvesting, and there is increasing concern over the sustainability of natural populations. Following standard procedures, mineral content and chemistry of soils sampled from the two sites were determined, and monthly (May to August) A. racemosa root, stem, and leaf mineral content were analyzed. Fresh tissue samples were processed for isolation and genotyping of associated endophytic organisms, and classical root staining was used to assess presence and extent of the arbuscular mycorrhizal (AM) symbiosis. Results showed that forest soils in the natural habitat of A. racemosa are slightly acidic (pH 4.5–6.0; 40–70% base saturation) with high organic matter (6–25%) and microelement content. Significant (P ≤ 0.05) variation was observed in seasonal concentration of key elements in leaf, stem, and root samples, with high levels of iron (Fe), aluminum (Al), manganese (Mn), and zinc (Zn) sequestered in root tissues. Root colonization by AM fungi was found to be high (85–100%) at both locations throughout the sampling period. A total of 22 fungal and 24 bacterial endophytes were isolated from A. racemosa root, shoot, and flower organs. Molecular characterization revealed bacterial isolates to be primarily Bacillus, Pseudomonas, and Serratia spp., whereas fungal isolates included Alternaria, Cadophora, Diaporthe, Penicillium, and Volutella spp. We conclude that potential exists for managed cultivation of black cohosh in arable land. Further, our findings confirm endophytic (mycorrhizal and nonmycorrhizal) associations in A. racemosa. We believe associated organisms could play a role in the adaptation of A. racemosa to the Appalachian ecosystem and recommend further examination of these relationships.

Primary old-growth forests are rare in the state of Indiana and are found only in small, isolated patches of nature preserves. Recent research underscores the values of large tracts of secondary old-growth (referred to in this paper as “older” forests), including carbon sequestration, forest resiliency, mitigation of climate change impacts, and conservation of biological diversity. Due to historical management, many portions of Indiana state forests are maturing, and yet the “older” successional stage is underrepresented. One of these maturing forests, the site of our study, is in south-central Indiana within the Back Country Area (BCA) of the Morgan-Monroe/Yellowwood State Forest (two state forests, herein called a complex, including parcels in three counties with the largest block of forests spanning Brown and Monroe counties). Our study of the forest structure of the BCA addresses the following questions: (a) Is this mature forest developing ecological attributes of old-growth forests, thus making it a good candidate for an older forest reserve? (b) Does this forest support the plant community characteristic of natural areas of Indiana? We analyzed forest stand metrics, coarse woody debris and snags, age of the largest live trees, and the floristic quality of the herbaceous layer. We then compared these data with published accounts from Indiana nature preserves. Metrics such as tree basal area, number of large-diameter trees, and number of snags are within the range of those measured in existing old-growth forests of Indiana. Analysis of tree cores and log cross-sections shows that 78% of the sample trees were over 100 yr old, with 24% over 130 yr, which is also comparable to old-growth forest nature preserves in the state. The metrics of the Floristic Quality Assessment of the broader plant community of the BCA are comparable to or higher than the metrics from published assessments of Indiana nature preserves. Collectively, the attributes measured indicate that the BCA supports a maturing secondary forest with old-growth characteristics. In the absence of further timber harvest, the BCA as a reserve could reach older forest status within 50 yr. Our study demonstrates that the BCA forest is a prime candidate for an older forest reserve. This study of the BCA could also serve as a model for future assessments of potential older forest reserves in other state forests. Reserves of older forests free from harvest are not incompatible with other management goals and can be a valuable part of a broader-scale management plan. These forest reserves should be promoted across the state to increase the representation within Indiana's state forest system of late-successional secondary forest exhibiting ecological attributes of old-growth forests, thereby enhancing the role of state forests in biodiversity protection and climate mitigation.