Pennsylvania sedge (Carex pensylvanica) has horticultural and restoration potential, but the achenes are difficult to germinate due to complex dormancy requirements. This study identified treatments to overcome physiological dormancy and determined light and temperature requirements for optimum germination. We first tested the effects of perigynia removal and light on achene germination. In the second experiment, achenes were subjected to varying durations of dry-cold or dry-warm storage conditions and a presowing soak in gibberellic acid (GA3). In a third experiment, we studied whether storage conditions, cold stratification, and sowing temperatures affected germination. Pennsylvania sedge germination was improved by dry-warm storage, perigynia removal, cold stratification, and germination in light.
Pennsylvania sedge (Carex pensylvanica) is an upland forest sedge with restoration and horticultural potential as a low-maintenance groundcover for dry shade. For large landscape and restoration plantings, seed or achenes in this case are much preferred due to lower labor and material costs. However, pennsylvania sedge typically produces few achenes in its native habitat. As a first step in improving achene production, this research evaluated the effect of vernalization and photoperiod on floral initiation and development. We conclude that this sedge is an obligate short-day plant that does not require vernalization for flowering. Plants flowered when exposed to daylengths of 6 to 12 hours. Flowering was completely inhibited with 14-hour photoperiods. Pennsylvania sedge was florally determined after 4 weeks of 8-hour photoperiods. Inflorescence quantity and normal floral development varied by clone and by weeks of exposure to 8-hour photoperiods. For two of the clones, the largest number of normal monoecious inflorescences was produced with 8 to 10 weeks of 8-hour photoperiods while the other two clones only required 6 to 8 weeks of exposure to inductive photoperiods. Therefore, it is important to evaluate observable variation between clones when attempting to propagate pennsylvania sedge.
Although sedges (Carex L. spp.) are commonly recommended for planting in rain gardens, little work has been carried out in evaluating the ability of sedge species to tolerate the challenging moisture fluctuations in this environment. Seven sedge species native to the north central United States, yellow fox sedge [Carex annectens (E.P. Bicknell) E.P. Bicknell], plains oval sedge [Carex brevior (Dewey) Mack. ex Lunell], gray’s sedge (Carex grayi J. Carey), porcupine sedge (Carex hystericina Muhl. ex Willd.), palm sedge (Carex muskingumensis Schwein.), pennsylvania sedge (Carex pensylvanica Lam.), and sprengel’s sedge (Carex sprengelii Dewey ex Spreng.), were evaluated in a greenhouse trial to determine their ability to tolerate repeated flooding and drought cycles. Treatments consisted of two flood periods (2 or 7 days), followed by one of three drought set points measured by volumetric water content (VWC) thresholds of 0.05 (severe drought), 0.10 (moderate drought), or 0.15 m3·m−3 (drought onset). Each plant was subjected to a minimum of four flooding and drought cycles. For sprengel’s sedge, plains oval sedge, gray’s sedge, and yellow fox sedge, there was no significant difference in shoot counts between severe drought, moderate drought, and drought onset treatments. Shoot mass and root mass for all sedge species were significantly reduced under the severe drought set point. Plants subjected to the 7-day flood treatment exhibited significantly increased shoot mass compared with those in the 2-day flood treatment. Plains oval sedge showed a significantly higher shoot mass than all other species under all treatments. Visible damage ratings suggest that sprengel’s sedge, plains oval sedge, gray’s sedge, and yellow fox sedge could be suitable for the rain garden environment under all but the most extreme drought conditions. Results show that plains oval sedge, yellow fox sedge, and gray’s sedge may be able to tolerate harsh flooding and drought cycles that can occur in rain gardens. For the remaining species, supplemental irrigation of rain gardens should be considered during drought.
Many pollinator insects, especially honey bees [Apis mellifera Linnaeus (Apidae)] and wild bees, are experiencing population decline because of forage and habitat losses. Planting perennial flowering taxa is one method of increasing pollinator habitat. The objectives of this study were to evaluate the potential of 27 native species and ornamental perennial cultivars to determine their ability to attract insect pollinators in a rural and an urban landscape in North Dakota, assess the potential of these perennials to attract other beneficial insects and insect pests, and identify the bee species visiting these perennials. Five to eight native species and/or ornamental cultivars each from four genera, Monarda L. (bee balm), Hylotelephium H. Ohba (stonecrop), Baptisia Vent. (wild indigo), and Symphyotrichum Nees (aster), were tested. Weekly observations of individual plants during flowering and their pollinator visitations from 2018 to 2020 indicated that insect pollinators were present for the earliest flowering perennials in June and until the latest flowering perennials during the second week of October or the first freeze. A total of 16,194 insect pollinators were observed, and 87.8% of these pollinator visitations were Hymenoptera and Diptera. Significant landscapes × perennial flowering taxa interactions were detected for all insect groups, except for syrphid flies, for which both main effects were significantly different. Overall, honey bees and beetles preferred to visit Hylotelephium and Symphyotrichum. The wild bees, lepidopterans, and syrphids preferred Hylotelephium, Symphyotrichum, and Monarda. Tachinids preferred Symphyotrichum. Blow flies preferred Hylotelephium. More beneficial insect visitations (i.e., 96.0%) and fewer insect pest visitations (i.e., 30.4%) were counted on the rural landscape. A total of 3311 bee individuals were identified as species from the following families: Apidae, Andrenidae, Colletidae, Megachilidae, and Halictidae. Thirty-one and 21 bee species were unique to the rural and urban landscapes, respectively. The two most common wild bees were Ceratina calcarata Robertson on the cultivar S. oblongifolium (Nutt.) G.L. Nessom October Skies and Lasioglossum imitatum (Smith) on some Monarda and Hylotelephium. These findings suggest that pollinator visitations are influenced by the landscape and varied among the perennial flowering taxa in some cases. However, all evaluated perennial flower taxa would be suitable for attracting and supporting pollinators in rural or urban landscape settings in the northern Great Plains.