Members of the genus Trillium are widely distributed in temperate hardwood forests. Due to shared life history traits, including long maturation, self-incompatibility, and limited seed dispersal, the genus is sensitive to anthropogenic disturbance, which reduces plant abundance and fecundity. In the southern Appalachian Mountains, Trillium species are widespread across a range of forest types, but are less common in secondary forests that originated following the abandonment of degraded agricultural land. One exception is Trillium luteum, which commonly occurs in floodplains formerly used as homesteads and farmland. We examined five populations of T. luteum in Great Smoky Mountains National Park to quantify population characteristics of this common, but rarely studied, species and relate these characteristics to historic disturbance. Plants within our sampled populations ranged in minimum age from 2 to 24 yr, with an overall mean age of 9.5 ± 0.4 yr. However, many plants may have been much older than our estimates due to rotting of the rhizome tip. We observed generally continuous recruitment across sites, but some sites displayed distinctly fewer young plants. Neither mean T. luteum density (plants 100 m^–2) by life stage nor mean plant age were correlated with overstory density or stand age (P > 0.102). We found that 20% of single-leaf plants originated from sprouts on fragments of old rhizomes. This ability to reproduce vegetatively has been observed in other sessile Trillium species and may provide a reproductive advantage in floodplains and former agricultural lands exposed to regular substrate disturbance.

Although the conditions that render forests likely to support nonnative plants are well documented, there are surprisingly few data on the long-term dynamics of nonnative invasive species in eastern temperate forests. We examined 11 years of compositional and structural change in a small (60 ha) forest preserve in Connecticut with abundant invasive plants, a diverse land use history, and varied edaphic characteristics. We quantified the extent to which vegetation composition changed at the species, life form, and community scales and then assessed the possible factors driving these changes. Fifty-four plots were sampled in 2004, 2009, and 2015; these plots spanned two major forest types, (a) Acer rubrum L.-Fraxinus americana L and (b) Quercus montana Willd.-Quercus coccinea Muenchh. Significant changes in composition occurred over time with a greater magnitude of change in the Acer-Fraxinus forest than in the Quercus forest at all scales of analysis. Large increases in the abundance of the invasive Microstegium vimineum (Trin.) A. Camus (+1760%), Berberis thunbergii DC. (+180%), and Rosa multiflora Thunb. ex Murr (+1790%), along with a surprisingly large decline in the dominant Alliaria petiolata (Bieb.) Cavara & Grande (–86%) occurred in the Acer-Fraxinus forest. Native shrub and herb life forms growing alongside these invasive species remained unchanged or increased in abundance. Soil moisture predicted change in abundance of R. multiflora and B. thunbergii. Our results suggest that A. petiolata may be less persistent over time than previously believed and underscore the difficulties of generalizing about invasive species dynamics and relationships with native plants.

Pennisetum setaceum (Forssk) Chiov. is a perennial C4 bunchgrass native to North Africa that has become widely naturalized or invasive outside of its native range. It commonly grows in disturbed habitats, which may have high levels of soil phosphorous (P). While nitrogen (N) addition and mixed-nutrient addition have been shown to increase growth and flowering in P. setaceum, no previous research has directly tested the effects of elevated soil P. We used a nutrient addition greenhouse experiment to test the effects of elevated P and N availability independently and in combination. N-treated plants grew faster and larger, were less stressed (as measured by maximum quantum yield of photosystem II, F_V/F_M), flowered earlier, and produced more inflorescences than plants not treated with N. P-treated plants were significantly larger compared to controls, but the difference in size was small. We show that N is the nutrient more strongly limiting the growth and reproduction of P. setaceum. We suggest that the affinity of P. setaceum to habitats of characteristically high P availability may reflect other, similar characteristics of these habitats, such as high disturbance rates.

In this study the environmental factors influencing foliar anthocyanin production in Pinguicula planifolia, a carnivorous plant whose leaves express varying colors of red and green, were examined. Seven P. planifolia sites within the Florida Panhandle were used. At each site, chlorophyll and anthocyanin content in leaves and environmental factors (light intensity, water depth, soil/water nutrients and pH, and vegetation height) were measured. At one of the sites, a light manipulation study (i.e., control, clipped, and caged) was conducted to test the effects of normal, heightened, and lowered solar radiation on red and green plants. Overall, foliar anthocyanin was influenced by environmental factors (i.e., light intensity as affected by water depth and vegetation height, vegetation cover, soil/water nutrient content) and the light manipulation study confirmed the role of light intensity on anthocyanin production. This study provides evidence that light intensity alone can effectively increase or decrease anthocyanin production in P. planifolia. Further work is needed to determine if anthocyanins may serve as a type of protective screening from ultraviolet radiation in this species.

Rare plant species can be at risk of hybridization, reduced genetic variation, and genetic assimilation when a numerically abundant congener co-occurs in or invades their habitat. We investigated hybridization between a species in decline, Asclepias purpurascens L., and its common and widespread congener, Asclepias syriaca L. A total of 40 morphological traits were measured on 60 flowering plants from a mixed population in Connecticut. Cluster and principal component analyses identified two distinct clusters of parental species taxa and a third cluster representing putative hybrids. Although leaf traits of putative hybrids were more similar to A. syriaca, floral traits and the morphological space on the principal component analysis were more similar to A. purpurascens. This suggests that the population contains a mix of F1 and advanced generation hybrids with the possibility of introgression into A. purpurascens. Although putative hybrids are intermediate for most traits, pollen counts reveal reduced fertility of presumed hybrid that might influence mating behaviors and increase the likelihood of backcrossing with A. purpurascens. We suggest a combination of morphological traits that better identify the two parental species as well as hybrids in the field. Conservationists should consider options of managing A. syriaca where A. purpurascens needs protection from competition to prevent genetic assimilation of the latter.

Few studies have reported on the morphology of Malveae fruits; particularly scarce are those examining internal morphology. The fruits of Malveae are considered schizocarps, and inside the mericarps, they have an appendix termed as the endoglossum. This structure presents different degrees of prominence among genera of the tribe, ranging from vestigial to well-developed. Although the external morphology of the endoglossum in Gaya has been studied, few studies have described its anatomy and ontogeny, knowledge which would contribute to our understanding of the evolution of such structure in the context of Malveae. Therefore, we herein propose to establish the origin of the well-developed endoglossum based on the ontogenesis of fruits of two species of Gaya, G. domingensis Urb. and G. gaudichaudiana A.St.-Hil., as well as a description of its tissues. To accomplish this, the usual techniques in plant anatomy were used to produce permanent slides for optical microscopy and sample preparation for scanning electron microscopy. Based on these studies, it was determined that the endoglossum structure in Gaya species has mixed origin, one from the basal portion of the carpelar mesophyll and another from the internal carpel epidermis. It can be concluded that the endoglossum, as herein validated, is a useful character for systematic and phylogenetic analyses in Gaya.

Monardella is a western North America genus ranging from the Rocky Mountains to the Pacific Ocean and from southern Canada to the southern tip of Baja California Sur. The levels of unrecognized and cryptic taxa within Monardella are similar to other taxonomically complicated western North American genera, such as Eriogonum (Polygonaceae), Penstemon (Plantaginaceae), and Oreocarya (Boraginaceae). We present variation in trichome morphology as a taxonomic tool within Monardella, being comparable in importance to trichome variation in other plant families and genera (e.g., Brassicaceae, Draba; Loasaceae, Mentzelia; Solanaceae, Solanum). Trichome morphology within Monardella is a useful character to differentiate taxa and resolve taxonomic ambiguities. We present nomenclatural novelties and revisions for Monardella occurring in the Hells Canyon region along the lower Snake River of west-central Idaho and northeastern Oregon. We introduce the following taxonomic and nomenclatural changes. Monardella odoratissima Benth. var. neglecta Cronquist is recognized as a later homonym; a new name and rank are presented for it: M. perplexans Elvin, R. B. Kelley, & B. T. Drew. Two new species are described: M. kruckebergii Elvin, R. B. Kelley, & B. T. Drew and M. walwaamaxsia Elvin, R. B. Kelley, & B. T. Drew.

A new species, Cyanocephalus veadeiroensis, from the Chapada dos Veadeiros region, Goiás state, which was first recognized on Facebook, is here described and illustrated. This new species is unique due to the combination of densely imbricate leaves obscuring the stems, the leaves longer than the internodes, the secondary veins almost parallel to the main vein, the margin entire to serrate and the leaf apex acuminate. The new species is compared with morphologically similar species such as Cyanocephalus adpressus and Cyanocephalus lanatus. We also provide comments on the distribution, ecological aspects and recognition of this taxon.