Roan Mountain Bluet

Hedyotis purpurea var. montana is a herbaceous, cespitose (growing in tufts or clumps), a perennial distinguished by its large reddish purple flowers, small oval leaves, and compact growth form which flowers from late May through August and into September. Roan Mountain bluet grows in clumps of one to several hundred stems. The taxon is known to spread by horizontal rhizomes up to 5 cm long; therefore, a stem does not usually represent a genetically distinct individual. 

Site observations and accompanying estimates of abundance in this taxon are widely inconsistent due to varying methods of measuring clumps or patches as well as estimations of plants without defining stem counts. The recovery pan recognized eight extant populations of H. montana. As of 2014, there are 17 extant populations of this taxon which are distributed across numerous rock outcrops on the highest peaks of western North Carolina, eastern Tennessee, and southwestern Virginia. Ten of the 17 populations of H. montana consist of a single occurrence with no subpopulations. The remaining seven populations consist of 36 subpopulations largely occurring on Grandfather Mountain and Roan Mountain. 

Pollination occurs from small staphylinid beetles, bumblebees, syrphid flies, and ants. 

Habitat

H. montana occupies high elevations (over 5,000ft above sea level) rocky summits and cliffs in the southern Appalachian Mountains of western North Carolina, extreme eastern Tennessee, and south-western Virginia. These rocky summits and cliffs usually appear as smaller-scale, patchy habitats commonly found on mafic or felsic bedrock and embedded within a larger forested landscape consisting of Spruce-fir or northern hardwood forest and occasionally, high elevation read oak forest. H. montana can also appear as smaller outcrops; or over patches of talus or scree embedded within a grassy or heath bald habitat. 

Physical characteristics

Roan Mountain bluet is a cespitose perennial herb with unbranched or weakly terminally branched stems to 21 centimeters (cm) tall from a basal winter rosette. Cauline leaves are opposite, sessile, and typically ovate, 0.8 to 3.0 cm long and 0.6 to 1.3 cm wide. The flowers are reddish purple and funnel-shaped and the corolla has four lobes that are shorter than 8 to 12 millimeters (mm) long. This species is heterostylous with two flower morphs; in the pin form, the pistil style is longer than the stamen filaments, whereas, in the thrum form, the style is shorter than the filaments. 

Lifestyle

Roan Mountain bluet grows in high-elevation rocky summit plant communities, though some outcrop sites are found on grassy balds and include representatives of that community as well. On grassy slopes, growth began earlier in the season and led to taller plants occupying great group area, but neither reproductive output, number of leaves, or patterns of mychorhizal associations differed consistently between these habitats. H. montana emerged at least eight weeks earlier than all other species except Solidago glomerata which suggests a strategy for minimizing light competition. 

Reproduction

Asexual propagation occurs in late summer when Roan Mountain bluets begin to produce basal rosettes from rhizome buds.

The four main flower visitors, listed in decreasing order of probable pollination effectiveness (based on field observations of frequency, pollen loads, and movement distances), were small staphylinid beetles, bumblebees, syrphid flies, and ants. 

Geography

Roan Mountain bluet has been observed in higher elevations surrounding North Carolina’s Ashe, Avery, Watagua, and Mitchell counties.