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Advancements in molecular technology have reduced the constraints that the grain of observation, or the spatial resolution and volume of the sampling unit, has on the characterization of plant-associated microbiomes. With discrete ecological sampling and massive parallel sequencing, we can more precisely portray microbiome community assembly and microbial recruitment to host tissue over space and time. Here, we differentiate rarefied community richness and relative abundance in bacterial microbiomes of Salvia lyrata dependent on three spatial depths, which are discrete physical distances from the soil surface within the rhizosphere microhabitat as a proxy for the root system zones. To assess the impact of sampling grain on rarefied community richness and relative abundance, we evaluated the variation of these metrics between samples pooled prior to DNA extraction and samples pooled after sequencing. A distance-based redundancy analysis with the quantitative Jaccard distance revealed that rhizosphere microbiomes vary in richness between rhizosphere soil depths. At all orders of diversity, rarefied microbial richness was consistently lowest at the deepest samples taken (approximately 4 cm from soil surface) in comparison with other rhizosphere soil depths. We additionally show that finer grain sampling (i.e., three samples of equal volume pooled after sequencing) recovers greater microbial richness when using 16S rRNA gene sequencing to describe microbial communities found within the rhizosphere system. In summary, to further elucidate the extent host-specific microbiomes assemble within the rhizosphere, the grain at which bacterial communities are sampled should reflect and encompass fine-scale heterogeneity of the system.

Summary We report a four-year study of the dynamics of a population of Salvia lyrata L., growing in a greenhouse. The study exemplifies the population cage approach, which has been the basis of many long-term studies of dynamics of animal populations for over 50 years, but which has been overlooked by plant population biologists. The cohort of plants that founded the population had a very high probability of survival and, as adults, produced the greatest numbers of seeds and seedlings. Thereafter, the numbers of individuals in each stage class declined. This decline appeared to be a consequence of density-dependent processes. At the conclusion of the study, the population density was far lower than at the onset. The behaviour of the population differed from that of the population of S. lyrata studied in a nearby mown field in several respects, including timing of seedling emergence, average size of individuals and final density. Likely causes of these differences are discussed. We recommend the use of population cages in further studies of plant populations. Because it facilitates long-term observation, this approach can be of great use in elucidating the dynamic consequences of demography.

Coreopsis lanceolata L. and Salvia lyrata L. from local (Monticello, FL) and nonlocal seed sources were transplanted into a field and maintained under low input, noncompetitive landscape conditions for 2 years. Plants of both species from local seed sources began flowering and were in full bloom earlier than plants from the nonlocal seed sources. Nonlocal C. lanceolata were larger throughout the study. Local S. lyrata were taller than nonlocal plants only when local plants were in flower and nonlocal plants were not. Survival percentage of C. lanceolata was equivalent from both seed sources, but higher for local S. lyrata compared to nonlocal, at the conclusion of the study.

Horminum virginicum Linnaeus, Species Plantarum 2: 596. 1753. "Habitat in Virginia, Carolina." RCN: 184. Lectotype (Reveal & al. in Huntia 7: 236. 1987): [icon] " Melissa atrorubens, Bugulae folio" in Dillenius, Hort. Eltham. 2: 219, t. 175, f. 216. 1732. - Typotype: Herb. Sherard No. 42 (OXF). Current name: Salvia lyrata L. (Lamiaceae). Note: Although Epling (in J. Bot. 67: 10. 1929) noted a specimen in LINN as a standard specimen, this is not equivalent to a type statement (see Jarvis & al. in Taxon 50: 508. 2001)., Published as part of Jarvis, Charlie, 2007, Chapter 7: Linnaean Plant Names and their Types (part H), pp. 557-585 in Order out of Chaos. Linnaean Plant Types and their Types, London :Linnaean Society of London in association with the Natural History Museum on page 577, DOI: 10.5281/zenodo.291971

Individuals of Plantago lanceolata and Salvia lyrata, both herbaceous perennial species, were transplanted into plots of otherwise unmanipulted vegetation. Individuals came from one of 12 half—sibships (common mother). Individuals were marked and leaf and inflorescence numbers counted at intervals for 14 mo. Consistent differences among plots, in survivorship, size, and reproduction, were found in both species, although the plots were only metres apart. Causes of this spatial variation are discussed. Evidence for genetic and genetic x environmental variation in Plantago lanceolata is suggestive but not conclusive. See full-text article at JSTOR

In order to determine the potential for natural selection to promote genetic specialization to different environments, this study quantified genetic variation for response to conspecific density and to other aspects of the environment that vary spatially. The progeny of a random collection of Salvia lyrata, a perennial herb, were planted into the source field in a range of densities and into several closely neighboring locations. The highest density and particular locations induced significantly greater mortality relative to the remaining densities and locations, indicating major effects of density and spatial location on fitness. Over the duration of the entire study, there was also significant variation among families in mortality. The survival data gave no indication of variation among families in their responses to the range of environments. Conversely, results based on growth and size indicated that different families were favored in different densities and locations, in support of the hypothesis that environment-dependent selection promotes specialization to different environments in this species. The correlation among families between leaf number in high and low density was small and positive, indicating near-independence of performance in different densities.

Salvia lyrata, spec. nov. 3. Salvia foliis radicalibus lyratis dentatis, corollarum galea brevissima. Salvia corollarum labio superiore breviore; fauce patente. Gron. virg.8. Horminum virginianum erectum, urticae foliis, flore minore; Moris. hist.3. p.395. s.11. t.13. f.31. Habitat in Virginia ., Published as part of Linnaeus, Carolus, 1753, Species plantarum: exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas, Stockholm :Laurentius Salvius on page 23, DOI: 10.5281/zenodo.3931989

(1) Two experiments were conducted in a natural population of Salvia lyrata to investigate the effects of conspecific density on survival, fecundity and growth of established individuals. In both experiments, the density around monitored Salvia individuals was altered, either by removal of surrounding Salvia individuals within a specified distance, or by planting Salvia in as neighbours. (2) In both experiments, survival, fecundity and growth showed small responses to the density manipulations. The responses varied with individual size. In large individuals these traits tended to decrease with increasing density, whereas small plants were in several respects favoured by more crowded conditions. (3) The weakness of the responses to neighbours suggests that the population of mature Salvia is not strongly self-regulating at typical natural densities or that marked effects of crowding appear only after a delay of more than two years. Mortality at the seedling stage as well as density-independent determinants of growth appear to maintain the adult population below the threshold at which neighbour interactions have strong effects.