Janice M. Coons

Assessing genetic diversity for the USA endemic carnivorous plant Pinguicula ionantha R.K. Godfrey (Lentibulariaceae)

Understanding patterns of genetic diversity and population structure for rare, narrowly endemic plant species, such as Pinguicula ionantha (Godfrey’s butterwort; Lentibulariaceae), informs conservation goals and can directly affect management decisions. Pinguicula ionantha is a federally listed species endemic to the Florida Panhandle in the southeastern USA. The main goal of our study was to assess patterns of genetic diversity and structure in 17 P. ionantha populations, and to determine if diversity is associated with geographic location or population characteristics. We scored 240 individuals at a total of 899 AFLP markers (893 polymorphic markers). We found no relationship between the estimated population size with either of two measures of diversity (proportion of loci polymorphic, Pxa0=xa00.37; Nei’s gene diversity, Pxa0=xa00.50). We also found low levels of population genetic structure; there was no clear relationship of genetic isolation by distance (Pxa0=xa00.23) and only a small (but significant) proportion of genetic variation was partitioned amongst regions (2.4xa0%, Pxa0=xa00.02) or populations (20.8xa0%, Pxa0<xa00.001). STRUCTURE analysis found that the model with two inferred clusters (Kxa0=xa02) best described the AFLP data; the dominant cluster at each site corresponded to the results from PCoA and Nei’s genetic distance analyses. The observed patterns of genetic diversity suggest that although P. ionantha populations are isolated spatially by distance and both natural and anthropogenic barriers, some gene flow occurs among them or isolation has been too recent to leave a genetic signature. The relatively low level of genetic diversity associated with this species is a concern as it may impair fitness and evolutionary capability in a changing environment. The results of this study provide the foundation for the development of management practices that will assist in the protection of this rare carnivorous plant.

Germination of Two Seed Types from Three Dalea Species

Abstract Dalea species are legumes that often are included in seed mixtures used for prairie restorations. Three Dalea species (D. foliosa, D. candida, and D. purpurea) exhibit two different types of seeds: plump (well-rounded larger) and dented (wrinkled smaller) seeds. Differences in germination and viability of these two types of seeds have not been reported. Our objectives were to compare seed mass, germination and viability between these types of seeds for three Illinois Dalea species. Fruits were collected for D. foliosa from 1998–2001 (Will County) and for D. candida and D. purpurea from 2001–2003 (Kankakee, Tazewell and Will Counties). For each species, seed mass, germination and viability were determined per seed type (plump or dented). Seed mass was significantly higher for plump than dented seeds for all three species. For D. foliosa and D. candida, germination of dented seed exceeded that of plump seed in some years. For D. purpurea, germination was significantly greater for plump seeds in both years. For ungerminated seeds of D. foliosa, only the plump seeds were viable, whereas for D. candida and D. purpurea, both seed types were viable. A comparison of seed germination among all three species when collected in the same county and year showed lower germination for D. foliosa than for D. candida and D. purpurea. In summary, seed types play a significant role in germination of these three species, and D. foliosa has lower germination than D. candida or D. purpurea.

Floral Biology of Physaria ludoviciana (Brassicaceae), a Plant Rare to the Midwest

ABSTRACT Physaria ludoviciana (Brassicaceae) is rare in Illinois, Minnesota, and Wisconsin. Environmental effects on floral development are unclear. Both self-compatibility and self-incompatibility occur within Physaria species. Objectives were to describe flowers, to determine how photoperiod affects flower development, and to predict whether flowers are self-compatible or self-incompatible. For photoperiods, greenhouse-grown plants were placed in either 16 or 8 hr photoperiods. Inflorescences and open flowers were counted weekly. For pollination, flowers were self-pollinated or cross-pollinated. Plants developed inflorescences after 20 and 28 d in long and short days, respectively. Inflorescences/plant increased for both photoperiods throughout the study. In short days, plants produced more inflorescences (10.8/plant) than in long days (7.1/plant). Anthesis started at 48 and 56 d for long and short days, respectively. Blooming peaked at 83 d (4.9 flowers/plant/day) for long days, and at 98 d (3.5 flowers/plant/day) for short days. Cross-pollinated flowers produced fruits, while self-pollinated ones did not.

Influence of Reproductive and Environmental Factors on Population Size of Wild Hyacinth [Camassia angusta (Engelm. and A. Gray) Blank. (Liliaceae)], an Illinois Endangered Species

Abstract Wild hyacinth (Camassia angusta) is a perennial species native to mesic prairies of the midwestern and south-central United States. In Illinois, the only extant population of this state-endangered species is in a small section of degraded black-soil prairie along a railroad track right-of-way south of Elwin, Macon County. The objectives of this study were to determine the population status, seed production, and effects of scarification and stratification on germination of C. angusta. The population was surveyed from 1990 to 2007. A survey of other plant species present was conducted in 1999. The site consisted of approximately 75% native and 25% exotic species. The number of flowering stems of Camassia angusta fluctuated significantly (28 to 169 plants) during the course of this study. Prescribed spring burns and a construction equipment disturbance may be partially responsible for these fluctuations. A large percentage of undeveloped fruit, resulting in low seed production (<3,000), as well as low seed germination (8%), may be responsible for this populations inability to increase consistently in number of individuals.

The Role of Red Leaf Coloration in Prey Capture for Pinguicula planifolia

Abstract Anthocyanins in the leaves of carnivorous plants are suggested to play a role in prey capture. In this study, we investigated the role of red leaf coloration (an indicator of anthocyanins) on prey capture using Pinguicula planifolia (Chapmans Butterwort). Overall, red leaves had less prey (i.e., Collembola) than green leaves, suggesting that red coloration does not enhance prey capture for Chapmans Butterwort. However, the frequent presence of Collembola on leaves suggests that this plant species could be relying on other cues to attract prey (e.g., olfactory cues).

Effect of habitat structure on reproduction and prey capture of a rare carnivorous plant, Pinguicula lutea

Habitat degradation is one of the greatest threats to biodiversity worldwide and the main contributor to the decline of many carnivorous plant species. For carnivorous plants in the southeastern United States, including many Pinguicula species (butterwort, Lentibulariaceae), degradation via altered fire regime has been implicated in their decline. Despite this decline, limited empirical research has been conducted examining the influence of habitat structural changes (through natural succession or human management) on reproduction and prey capture by carnivorous plants. The objectives of our study were to compare reproduction and prey capture for Pinguicula lutea (yellow butterwort) in habitats with different vegetation structures in the Florida Panhandle, where differences were largely due to management history. Pinguicula lutea is a self-compatible carnivorous plant that inhabits fire-dependent longleaf pine savannas of the southeastern United States and is threatened in the state of Florida. In 2014 and 2015, 13 sites were identified occupying three different habitat structures: maintained (intermittently mowed), grassy (dominated by Aristida stricta var. beyrichiana), and woody (encroachment by Hypericum and Ilex). Reproductive output was determined by assessing fruit set and ovule fertilization rate at each site. Additionally, prey availability and prey capture were assessed at each habitat site. In general, there were no differences in either measure of reproduction across habitat structure types. There were differences in prey abundance of Collembola, Diptera, and total arthropods both in terms of availability and capture. Total arthropod availability and prey capture were lowest in grassy sites compared to maintained habitat sites and woody habitat sites. Microclimatic conditions associated with each habitat structure and leaf morphology or physiology could explain the observed arthropod abundance and prey capture patterns. This study is the first ecological assessment of plant–insect interactions for Pinguicula species of the southeastern US and highlights the importance of habitat quality and management for this understudied group of carnivorous plants.

Seed biology of Physaria ludoviciana (silvery bladderpod; Brassicaceae ), an endangered species in sand prairies of the Midwest

Abstract Physaria ludoviciana (Nuttal) OKane & Al-Shehbaz (silvery bladderpod) is a state endangered species in Illinois, Minnesota and Wisconsin, the eastern edge of its range. Our goal was to investigate its seed biology (production, dispersal, seed bank longevity, afterripening, seed longevity after storage using germination and emergence, and seedling establishment). This information will be useful for conservation efforts of this endangered species. Over a ten-year period, various seed biology parameters were measured. Infructescences were counted to estimate seed production with 110–744 seeds per reproductive plant. Soil samples were collected at various distances to estimate dispersal where seeds dispersed less than a meter, and also at various times to estimate longevity in the seed bank where only 4% as many seeds were found in November as in June. After-ripening tests used seeds imbibed every two months after harvest for ten months where germination rates increased when imbibition was delayed at least six months. Germination and emergence of stored seed was measured to estimate longevity. Seeds stored at 4 °C and 40–50% relative humidity remained viable for at least six years. For establishment and plant density, seedlings, vegetative plants, and reproductive plants were counted. For establishment, densities were 0–11 seedlings m−2. This seed biology information could be applied to conservation efforts for this endangered species.

Surveys of Stylisma pickeringii var. pattersonii (Convolvulaceae), Its Associated Plant Species, and Its Insect Visitors

Abstract Stylisma pickeringii var. pattersonii (Convolvulaceae) is endangered in Illinois and Iowa, and occurs in scattered populations in other states. During 1999 and 2000, two insect species previously unreported from Illinois were observed visiting its flowers. This study was undertaken to survey additional insect visitors, as well as to characterize the plant community where S. pickeringii occurs. The objectives were to survey: 1) floral traits (anthesis and flower density) of S. pickeringii, 2) associated plant species, and 3) insect visitor characteristics. Floral traits were determined and associated plant species surveyed in Mason County (degraded hay field on private property) and Henderson County (dry sand prairie at the Big River State Forest), Illinois. Insects visiting flowers were collected at 10:00 a.m., 12:30 p.m., and 3:00 p.m. during June, July, and August in 2001 and 2002. Individual flowers lasted one day and remained open for 6–8 hours. Peak flowering occurred from early to the middle of July when S. pickeringii was the dominant species in flower. Henderson County contained a greater diversity of native plant species with less bare ground and fewer non-native species than the Mason County site. Forty-seven insect species were observed visiting S. pickeringii flowers. Most frequent visitors were Apis mellifera (Hymenoptera: Apidae), Bombylius fraudulentus (Diptera: Bombyliidae), and Heterostylum croceum (Diptera: Bombliidae). The diversity of visiting insects was higher earlier than later in the day, in July and August than June, and in Henderson than Mason County.