22 September 2024.
Pennsylvania, United States
Locality: Outcrops along the Susquehanna River, accessed from the Historic Lock 12 parking lot off of Pennsylvania Road 372.
Coordinates: 39.8148, -76.3276
(Map it)
Elevation: 34m.
Georeference protocol: Lat/lon determined by GPS
Habitat: Wild Habitat
Environment description: Plants are growing from part-sun to full sun in crevices of the outcrops and where organic debris has accumulated in between boulders along the Susquehanna River. The sites range from nearly xeric to dry mesic, at least on the surface. Plants are generally growing 4-10 m above the normal flow of the river; however, the Holtwood Dam is less than 1 kilometer upstream and debris found trapped in the boulders indicates that there is periodic flooding, at least, in the lower zone of 4+ meters or so above normal river flow. This habitat has a diverse assemblage of deciduous trees and shrubs as well as abundant herbaceous taxa. Slope: 0 to 25 percent. Aspect: Northeast (generally). Geology: The underlying geology of this area is probably of lower Paleozoic age and characterized as the Octoraro Formation. It includes albite-chlorite schist, phyllite, some hornblende gneiss, and granitized members. Soils: The area where this species occurs is right on the edge of two soil zones that transition from the river’s edge to mesic conditions upslope. The first is generally referred to as Rock Outcrop. This terrestrial matrix in which plants grow is largely exposed underlying rock geology with accumulated outwash, rock decomposition, and organic debris buildup. The second is Mt. Airy (80%) and Manor (20%) Series soils, 25 to 60 percent slopes, extremely stony (MRF). (Source: California Soil Resource Lab/NRCS Official Soil Series Descriptions). EPA Ecoregion (Level III): Northern Piedmont (64). EPA Ecoregion (Level IV): Piedmont Uplands (64c).
Number of plants sampled: 20
Associated species: Baptisia tinctoria; Fagus grandifolia; Alnus serrulata; Collinsonia canadensis; Rosa carolina; Toxicodendron radicans; Schizachyrium scoparium; Solidago bicolor; Solidago racemosa; Vaccinium angustifolium; Acer rubrum; Acer saccharinum; Aronia melanocarpa; Betula nigra; Vaccinium stamineum; Vaccinium corymbosum; Hypericum prolificum; Ionactis linariifolia; Rubus sp.; Fraxinus pennsylvanica; Viburnum dentatum; Quercus montana; Nyssa sylvatica; Malus sp.; Platanus occidentalis; Symphyotrichum sp.; Ageratina altissima; Chionanthus virginicus; Phlox subulata; Lonicera japonica; Rhododendron arborescens; Hamamelis virginiana; Physocarpus opulifolius; Crataegus sp.; Rhododendron periclymenoides; Sedum sarmentosum; Parthenocissus quinquefolia; Prunus serotina; Diospyros virginiana; Amelanchier sp.; Heuchera americana; Asplenium platyneuron; Carya glabra; Lindera benzoin; Asimina triloba; Ulmus americana; Viburnum prunifolium; Uvularia sessilifolia; Solidago juncea; Vitis sp.; Ilex verticillata; Carya cordiformis; Reynoutria japonica; Polystichum acrostichoides; Athyrium filix-femina; Eurybia divaricata; Tilia americana; Betula lenta; Quercus rubra; Rubus phoenicolasius; Liriodendron tulipifera; Veronicastrum virginicum; Sedum ternatum; Aquilegia canadensis; Thalictrum pubescens; Vaccinium pallidum; Pycnanthemum tenuifolium; Ambrosia artemisifolia; Cystopteris sp.; Carpinus caroliniana; Asplenium trichomanes; Rhus copallinum.
Comment: Plants are deciduous, multi-stemmed, sparsely branched, shrubs with an upright irregular spreading growth habit ranging from 0.5-2.0 m tall x 1-3 m or more wide. The lower stems are woody; the gray bark is relatively smooth with scattered small lenticels. The upper stems are dull light green and pubescent. Leaves are odd-pinnately compound with 10-30 leaflets and reaching 15-30 cm long. The overall outline of the compound leaves is lanceolate-ovate; widest toward the middle and narrower toward the base and tip. Both the leaf petioles and central stalks of the leaves are light grayish-green and pubescent. The leaflets are dull gray-green and sparsely canescent; scattered translucent glands are visible and resemble small dots. Clusters of fruiting racemes are borne terminally on upper stems. Individual racemes are erect to ascending, 7.5-20 cm long, and cylindrical in shape. Many small seedpods about 0.5-0.6 cm long (or a little more) are borne on the raceme, each containing 1-2 seeds. The seedpods are obovoid and somewhat flattened, terminating in short beaks; their outer surfaces are glandular-punctate. This species is common on the boulder outcrops and woodland edge along this portion of the Susquehanna River. Seed collected from 20 plants; approximately 5,500 to 6,500 fruits collected.
Collector(s):