Propagation of Four Underused Native Species from Softwood Cuttings

Interest in native plants for landscaping is increasing and nursery growers must expand their product offerings by adding new native species. Softwood stem cutting propagation of four underused northeastern U.S. native species [Ceanothus americanus (L.), Corylus cornuta (Marsh.), Lonicera canadensis (Bartr.), Viburnum acerifolium (L.)] was studied. V. acerifolium cuttings containing two nodes taken mid-June to mid-August rooted at nearly 100% with at least 15 roots per cutting. Exogenous auxin application did not enhance rooting of two-node V. acerifolium cuttings. Single-node V. acerifolium cutting success and quality of rooting increased with increasing concentration of auxin applied and reached a maximum of 80% rooting, whereas untreated cuttings only rooted at 53%. C. cornuta cuttings taken mid-June to mid-August rooted at greater than 85%. Hormone concentration did not affect rooting percentage for C. cornuta; however, cuttings treated with 3000 and 8000 ppm indole-3-butyric acid (IBA) had more and longer roots than untreated cuttings. June was the optimal time to collect cuttings of C. americanus (57% rooting) and L. canadensis (49% rooting), and rooting hormone did not significantly impact propagation success. C. cornuta and V. acerifolium could be propagated at a level necessary for consideration as a new commercial crop by general wholesale nurseries looking to add select native shrubs to their product lines. All four species evaluated could be viable commercial crops for nurseries that specialize in native plants.

Evidence for community structuring associated with the actinorhizal shrub Ceanothus americanus in tallgrass prairies in Illinois, USA

The role of the actinorhizal shrub Ceanothus americanus L. in community organisation of native grasslands was examined in three Illinois tallgrass prairie remnants. We asked can C. americanus structure tallgrass prairie at the patch scale through nitrogen fixation leading to differences in species assemblages and diversity? Expectations were that warm season (C4) graminoid species would be more abundant and species diversity would be greater outside Ceanothus patches than in patches associated with C. americanus where, based on results from numerous nitrogen augmentation and deposition studies, we expected greater abundance of cool season (C3) graminoid species and lower species diversity. Plots with and without association to C. americanus were compared for differences in floristic similarity, diversity, and C3 versus C4 graminoid species abundance. C3 graminoid species, including the adventive Poa pratensis L., were significantly more abundant in prairie associated with C. americanus than were C4 species. C4 species, such as Andropogon gerardi Vitman and Schizachyrium scopariumii (Michx.) Nash., were more abundant than C3 graminoid species in prairie patches without association to C. americanus. Means for diversity among plots associated with C. americanus were significantly lower than for other plots, nearly so for evenness and species density, but not different for sum total cover or total species richness. There were no statistically-significant differences in measures of mean total soil nitrogen at points along linear transects radiating from the base of C. americanus shrubs nor between mean soil amino-sugar-nitrogen concentrations within and outside of C. americanus patches. Nonetheless, comparative evidence supports the hypothesis that C. americanus structures composition and diversity at the local patch scale in tallgrass prairie.

Brief Exposure to Boiling Water Combined with Cold-moist Stratification Enhances Seed Germination of New Jersey Tea

Although there is increasing interest in propagating prairie plants native to the midwestern United States for managed and natural landscapes, several species, including new jersey tea (Ceanothus americanus), are difficult to germinate from seeds. New jersey tea, which is an attractive, compact woody shrub, is found in high-quality prairie remnants throughout the tallgrass prairie region. Developing a protocol to increase the uniformity of seed germination in this species would allow for more widespread horticultural cultivation of this stress-resistant, nitrogen-fixing species. We hypothesized that the germination response of seeds of new jersey tea would be enhanced by replicating conditions that mimic their natural environment, which included treatments under controlled conditions exposing seeds to chilling temperatures, sulfuric acid, and boiling water. Two minutes of exposure to boiling water followed by 60 days of cold-moist stratification at 4 °C resulted in the highest germination percentage (48%) and mean daily germination (2.18 seeds/day). Scarification with 98% sulfuric acid for 15 min followed by 60 days of cold-moist stratification resulted in significant, but lower levels of germination percentage than seeds exposed to boiling water and cold-moist stratification. Cold-moist stratification in darkness and in an 18-hour photoperiod at 4 °C did not stimulate germination to a level suitable for production purposes. However, tetrazolium tests indicated that 79% of the seeds were viable. We conclude that cold-moist stratification should be used with boiling-water or acid-scarification to uniformly produce germinated seedlings of new jersey tea. However, nonresponsive seeds should not be discarded because they may germinate in later years if kept under appropriate conditions.

Phylogenetic placement of unculturedCeanothusmicrosymbionts using 16S rRNA gene sequences

Full-length 16S rDNA sequences were amplified directly from the nodules of Ceanothus americanus L. and Ceanothus thyrsiflorus Eschsch. using the polymerase chain reaction. Sequences were determined using an automated sequencer, compared against those in GenBank, and assembled into consensus sequences. The sequences were aligned with other full-length Frankia 16S rDNA sequences available from the data base. Phylogenetic trees were obtained using three different algorithms: neighbor joining, parsimony, and the maximum-likelihood method. All three methods showed that these Ceanothus L. microsymbionts were most closely related to the microsymbiont associated with Dryas drummondii Richardson ex Hook. Lvs. rather than Frankia isolated from the Elaeagnaceae.Key words: Frankia, Ceanothus, 16S rDNA.

Diversity of Frankia Strains in Root Nodules of Plants from the Families Elaeagnaceae and Rhamnaceae

ABSTRACT Partial 16S ribosomal DNAs (rDNAs) were PCR amplified and sequenced from Frankia strains living in root nodules of plants belonging to the families Elaeagnaceae and Rhamnaceae, includingColletia hystrix, Elaeagnus angustifolia, an unidentified Elaeagnus sp., Talguenea quinquenervia, and Trevoa trinervis. Nearly full-length 16S rDNAs were sequenced from strains ofFrankia living in nodules of Ceanothus americanus, C. hystrix, Coriaria arborea, and Trevoa trinervis. Partial sequences also were obtained from Frankia strains isolated and cultured from the nodules of C. hystrix, Discaria serratifolia, D. trinervis, Retanilla ephedra, T. quinquenervia, and T. trinervis (Rhamnaceae). Comparison of these sequences and other published sequences ofFrankia 16S rDNA reveals that the microsymbionts and isolated strains from the two plant families form a distinct phylogenetic clade, except for those from C. americanus. All sequences in the clade have a common 2-base deletion compared with other Frankia strains. Sequences from C. americanus nodules lack the deletion and cluster withFrankia strains infecting plants of the family Rosaceae. Published plant phylogenies (based on chloroplast rbcLsequences) group the members of the families Elaeagnaceae and Rhamnaceae together in the same clade. Thus, with the exception ofC. americanus, actinorhizal plants of these families and their Frankia microsymbionts share a common symbiotic origin.