Lonicera maackii (Rupr.) Herder (Amur honeysuckle) is one of the most important invasive plants in the Ohio Valley. Because of its phenology and dense canopy, L. maackii can exclude native herbs and interfere with regeneration of woody plants. In 2005, in a county park in southwest Ohio, I established modified Whittaker plots in four stands with a gradient of L. maackii cover ranging from 24 yr old to 40 yr old. The L. maackii canopies were removed by herbicides in fall 2005. Plant cover was monitored from 2005 to 2013. After 8 yr, there was an increase in species richness and herbaceous cover at all sites. Herbaceous species turnover was generally greater at sites with greater initial L. maackii cover. All of the most-common herbaceous species increased or maintained their coverage; most of the species that increased were those that bloom in late spring or summer. The abundances of other invasive species also increased, including Alliaria petiolata (M. Bieb.) Cavara & Grande (garlic mustard). However, A. petiolata abundance peaked 2–6 yr after L. maackii removal, suggesting that this increase, frequently seen after L. maackii removal, may be transitory. Previous studies have not shown such a decline after an initial increase in A. petiolata, but few studies have extended over this length of time. Ash (Fraxinus L.) decline caused by the emerald ash borer may now be affecting the recovery of these stands.

While hunting is employed as a means to control overabundant populations of white-tailed deer (Odocoileus virginianus) and reduce the negative effects of herbivory, few studies have examined whether recovery of forest regeneration occurs following a long-term controlled hunting program. In Indiana state parks, controlled hunts were implemented in the 1990s to reduce deer population abundance and allow vegetation communities to recover. In 1996 and 1997, long-term vegetation monitoring plots were established in 16 state parks and six historically hunted reference areas to monitor vegetation response to hunting. We resampled these plots in 2010 to examine how deer reductions affected woody stem density and species composition in three height classes: < 50 cm, 50–200 cm, and > 200 cm. We also examined changes in species richness (S), evenness (E), and Shannon-Wiener diversity (H′) between 1996–97 and 2010. Temporal changes were tested with generalized linear mixed models. Density in the < 50 cm height class increased significantly in both state parks and reference areas. Density in the 50–200 cm height class increased significantly in parks, but not in reference areas. Species richness increased significantly in all three height classes in parks, but only in the > 200 cm class in reference areas. Density of Fraxinus americana and Acer saccharum increased greatly in the < 50 cm and 50–200 cm height classes in both state parks and reference areas. While still abundant in the parks, two unpalatable species, Asimina triloba and Lindera benzoin exhibited reduced relative density in the < 50 cm height class. Within parks and reference areas, the density of these species increased in the > 200 cm height class. These results indicate that the void in forest understories created by chronic herbivory in Indiana state parks is being filled by a diverse array of species following deer population reductions. In addition, the species composition of parks has become more similar to that of reference areas through time.

Flowering phenology may play a critical role in plant coexistence, allowing not only a temporal partitioning of resources but also conditioning the relationship between seed mass and number in these species. We analyzed how flowering phenology was related to seed mass and number, and how these seed traits were related in five coexisting Gymnocalycium (Cactaceae) species in two consecutive flowering seasons. The flowering phenology of each species was characterized in terms of timing (onset and peak), duration, and flowering synchronicity. Although species showed differences in duration and synchronicity, the earliest flowering species tend to have higher reproductive success than species flowering later. However, we did not find a clear relationship between the flowering time and seed traits. A trade-off between seed mass and number in these species was highlighted, as species with higher seed mass were those producing a lower number of seeds per fruit and individual, whereas species with lower seed mass had a higher number of seeds. Our results showed a temporal resource partitioning associated with differences in flowering timing among species, which may lead to differences in reproductive success (number of mature fruits and fruit set) and highlight the importance of the trade-off between colonization vs competitive ability in promoting plant coexistence.

Research has shown that older plants of more than 20 species of tall, long-lived cacti of the Americas have surface bark injuries. This bark is caused by sunlight exposures over several decades. This bark formation (which first appears on south-facing surfaces) leads to premature morbidity and eventually premature mortality (rates of 2.3% per year for Carnegiea gigantea. Current research was aimed at changes in C. gigantea bark formation over a 4-yr period. Of the 89 C. gigantea analyzed, 35% died. Among survivors, surface areas with bark increased by 20% over the 4-yr period. Rib troughs of a more southerly orientation had more bark injuries (up to 15% more) than troughs with a more northerly orientation. Over time, the amount of bark on north-facing troughs becomes similar to bark levels on south-facing troughs. Machine learning techniques that used 18 parameters of bark percentages on cactus surfaces had an 84% probability of predicting cactus death with two independent methods. Machine learning techniques also made accurate predictions about rates of bark formation (morbidity). As expected, cacti with high bark percentages were predicted to be the most vulnerable to die in coming years as compared with cacti with less bark. Since many tall, long-lived cactus species of the Americas exhibit extensive bark formation, the current results suggest that bark can lead to death of adult plants over relatively short time periods for such long-lived cactus species. This study combined two disciplines, namely visual/digital estimates of bark formation in columnar cacti and its links to morbidity/mortality with machine learning techniques. These two very different disciplines combined to produce results that could not be accomplished alone.

Populations of wide-ranging plant species may vary significantly from one another with respect to physiological and reproductive traits, allowing each population to adapt to its local environment. One example of this variation is observed as differences in floral form and breeding system. In the California wildflower Clarkia tembloriensis Vasek, breeding system varies from populations of outcross-pollinating individuals, with relatively large, protandrous flowers, to populations of self-pollinating individuals, with small, nonprotandrous flowers. Variation within the selfing flower types includes populations with small flowers that are polymorphic for petal form; WT (flowers with normal expanded petals) and crinkle-petal (cp; flowers with small, unexpanded petals). The aims of this study were to investigate the nature of this variation in floral biology with respect to resource allocation to male and female function and to components important for reproductive success in the six California populations included in this study. Our study revealed that more resources were allocated to pollen production relative to ovule production in large, outcrossing flowers than in small, selfing flowers. Pollen deposition on the stigma was significantly higher in selfing flowers than it was in outcrossing flowers and significantly higher in cp selfing flowers than it was in WT selfing flowers. Despite these differences, sufficient pollen was deposited on stigmas in all populations to fertilize available ovules. The numbers of seeds produced per capsule was significantly lower in populations of C. tembloriensis, with small, selfing flowers than it was in large, outcrossing flowers, which was probably due to differences in rainfall amounts between populations. Large outcrossers occupy the core of the species range, whereas small selfers occupy marginal habitat. The differences we observed reflect adaptations of each population to their local environment.

Dyckia is characterized by conserved external floral and fruit morphology. Considering the conservative morphology of Dyckia fruits, anatomical features could be an important source of phylogenetically useful characters. The objectives of this study were to characterize fruit ontogeny and dehiscence in three species of Dyckia (Dyckia distachya, Dyckia reitzii, and Dyckia remotiflora), and in the process to identify characters that contribute to the systematics of the genus and family. Differences were found among species in the number of mesophyll/mesocarp layers, presence of pluristratified hypodermis, presence of mucilage secretory structures, and presence of perivascular bundle sheath extensions. In addition, a xerochastic mechanism of dehiscence in Dyckia denticidal capsules is described here for the first time. As a potential source of characters, fruit anatomical features can be useful at the generic and specific levels.

Xyridaceae comprise two subfamilies: Xyridoideae and Abolbodoideae, which are morphologically distinct. Orectanthe belongs to Abolbodoideae and comprises two species with restricted distribution. The anatomy of root, stem, leaf, and inflorescence axis of Orectanthe sceptrum was studied aiming to characterize the species in a comparative approach. The anatomy of the roots is first described here for the genus and they are characterized by presenting two distinct patterns according to their developmental stage and function. Intracellular papillae were observed in the epidermal and cortical cells, increasing the root absorption surface. These papillae are exclusive of O. sceptrum within the family as well as the following characteristics: epidermal cells with thickened outer periclinal walls in the stem, epidermal cells with U-shaped thickened walls in the leaf blade, and chlorenchyma with arm cells in both the leaf blade and inflorescence axis. Orectanthe shares with Abolboda an indistinct endodermis in the stem and a hypodermis beneath both leaf surfaces and in the inflorescence axis. A continuous pericycle in the root, stomata restricted to the abaxial surface of the leaf blade, vascular bundles with sheath extensions distributed in a single row in the mesophyll, and large lacunae in the leaf sheath are features shared by Orectanthe, Abolboda, and Aratitiyopea, characterizing Abolbodoideae. A great similarity was observed between Abolbodoideae and Eriocaulaceae, as both have roots with heterogeneous cortex and continuous pericycle, and bifacial, hypostomatic leaves presenting hypodermis and vascular bundles with sheath extensions.