Plant Evaluation Notes | Issue 45, 2020 A Comparative Evaluation of Ironweeds (Vernonia spp.)

Richard G. Hawke, Plant Evaluation Manager and Associate Scientist Vernonia gigantea

Ironweeds inhabit a broad swath of inflorescences of coneflowersEchinacea ( nonia lindheimeri var. leucophylla) sports the United States, from the mid-Atlan- spp.), asters (Symphyotrichum spp.), and bright silvery white linear leaves. Leaf size tic to the Midwest and from Minnesota sunflowers Helianthu( s spp.). Instead, up- enhances the robustness of some iron- south to Texas. While many are tall, even ward of 50 or more small tubular disk florets weeds; for example, giant ironweed (V. gi- towering in height, all ironweeds offer an are crowded into a compact flower head or gantea) reaches 8 feet tall, but the 10-inch abundance of purple-hued flowers in late capitulum, which is surrounded by involu- long leaves make it seem even larger. On summer and early fall. Their value as a food cral bracts or phyllaries that are unique to a the other hand, at 3 inches long and barely source for pollinators is irrefutable—scores species and helpful in identification. Phyl- wider than a sliver, the linear leaves of nar- of bees, butterflies, and numerous other in- laries are made up of whorls of small leaf- rowleaf ironweed (V. lettermannii) look sects feverishly work the flowers through- like structures that encase the flower more like Arkansas blue star (Amsonia hu- out the late bloom season. Ironweeds are heads, and may be leafy, spiny, or fringed. brichtii) than any of its kin. Ironweed leaves extraordinary ecological plants, due to their For several weeks beginning in mid- to late may be entirely smooth or hairy on the un- indigenousness and importance as power- summer, purple to magenta capitula bloom dersides—the soft fuzziness of Missouri house pollinator plants, but they are great in many-flowered inflorescences measuring ironweed’s (V. missurica) leaves and stems garden plants too. At a glance, some iron- up to a foot or more across. The genus is are a notable case. Most of the commonly weeds may seem too tall for many gardens, named for William Vernon (1688-1711), an cultivated species have woody, fibrous root but recent breeding has resulted in a num- English botanist who collected plants in crowns and stiff stems ranging from several ber of compact hybrid selections. The Maryland. The common name may be a feet to 10 or more feet in height. shorter ironweeds may have given up some nod to the iron-like rigidity of the stems, or size but have lost none of their ornamental more likely refers to the cinnamon-colored Ironweeds are generally easy to grow in full appeal or draw for pollinators. hairs on the fruit. sun and moist, well-drained soils but are often adaptable to light shade and drier Vernonia spp. are in the aster or daisy fam- Leaves are typically dark green and tend soils, and some species are drought-toler- ily (Asteraceae), but lack the showier pet- toward lance-shaped but can be willow-like ant once established. Silver ironweed, for al-like ray florets common to the composite to filiform. Conversely, silver ironweed (Ver- example, is best grown in lean, gravelly soil

Plant Evaluation Notes | chicagobotanic.org | 2 Vernonia lettermanii Vernonia lettermanii or decomposed granite, in full or half-day ing purple flowers attract a host of pollina- cold-hardy ironweeds. The trial group con- sun. Ironweeds tend to grow taller in moist tors. Ironweeds put on an impressive show sisted of 17 taxa in all—representing ten conditions. Many ironweeds are hardy to at in native and naturalistic landscapes, species with eight associated subspecies, least USDA Zone 5 or colder, while others meadows, and formal gardens. In early cultivars, or hybrid selections. Plants were are native to warmer places in the South- summer, the dark green foliage provides a acquired commercially or were grown from east and westward to Texas. Ironweeds are handsome backdrop for a variety of earlier wild-collected seeds; seed-grown species typically long-lived, growing into large -blooming perennials; whereas, late-sea- exhibited variable traits within a taxon and clumps over time, but rarely need division. son bloomers such as sunflowers (Helian- included V. arkansana, V. baldwinii, V. fas- Cutting stems back by half in late spring will thus spp.), goldenrods (Solidago spp.), and ciculata, V. gigantea, V. gigantea ssp. gi- reduce the ultimate plant height; while thin- big bluestems (Andropogon gerardii culti- gantea, V. glauca, V. missurica, and V. ning the crowns by selectively removing vars) make stellar floral companions. A noveboracensis. stems in spring increases air flow through shorter stature and feathery foliage sets the plant and can help reduce foliar diseas- narrowleaf ironweed (Vernonia lettermannii) The ironweed trial was originally initiated in es. Deadheading reduces unwanted seed- apart from other species, and provides a 2009 but was interrupted in 2010 by a ren- lings, which can be prolifically produced, pleasing textural contrast with bolder ovation project in the evaluation garden. especially in moist areas; however, dead- plants. Despite the large number of spe- Due to significant changes in bed design, heading removes a food source for cies—upward of 1,000 herbaceous and all plants were transplanted to pots and late-season songbirds. Powdery mildew woody plants from the Americas, Asia, Afri- moved to the production nursery in June and rust can infect foliage in late summer or ca, and Australia—ironweeds are not 2010. The original 11 taxa were replanted in fall—some species are more susceptible widely cultivated and still are uncommon in the trial garden in September 2011; the offi- than others. Disease levels can be severe, home gardens. cial restart of the trial began with data col- thus deleteriously affecting plant health. lection the following spring. Several new The bitter-tasting leaves are usually not pal- The Evaluation Study taxa were added to the trial between 2012 atable to most grazing mammals including and 2015 including Vernonia angustifolia The Chicago Botanic Garden (USDA Hardi- deer. ‘Plum Peachy’, V. gigantea ssp. gigantea ness Zone 5b, AHS Plant Heat-Zone 5) un- ‘Jonesboro Giant’, V. noveboracensis dertook a comparative trial of Vernonia Ironweeds are both a boon and a challenge ‘White Lightning’, V. ‘Southern Cross’, V. species and cultivars from 2012 through to gardeners—their size can be daunting ‘Summer’s Surrender’, and V. ‘Summer’s 2018. The goal of the trial was to determine for average gardens, but their late-bloom- Swan Song’. the garden-worthiness of a variety of

Plant Evaluation Notes | chicagobotanic.org | 3 Vernonia 'Summer's Surrender' Vernonia 'Summer's Surrender'

Five plants of each taxon were grown in The Performance Report The fine-textured inflorescences and upper side-by-side plots for easy comparison of In the trial, the ironweeds were regularly ob- stems were dark burgundy. Flower produc- ornamental traits and landscape perfor- served for their cultural adaptability to the tion was consistently heavy, with smallish, mance. The evaluation garden was openly soil and environmental conditions of the full ¾-inch-wide purple flower heads; the inflo- exposed to wind in all directions and poten- sun evaluation garden; diseases and pests; rescences were commonly more than 12 tially received up to ten hours of full sun dai- winter hardiness and survivability; and or- inches wide. The large, dark green leaves ly during the growing season, which aver- namental qualities associated with foliage, were generally healthy, with only minor pow- aged 175 days per year for the 2012-2018 floral display, and plant habits. Final perfor- dery mildew observed. The late bloom peri- trial period (see Table 1). The clay-loam soil mance ratings shown in Table 2 are based od of ‘Jonesboro Giant’—late September to had a pH of 7.4 during this period, and al- on foliage and habit quality, flower produc- early November—was occasionally truncat- though typically well-drained, the site occa- tion and floral display quality, plant health ed by early frosts in October; the historical sionally retained excess moisture for short and vigor, and winter hardiness. All taxa frost date at the Chicago Botanic Garden is periods in all seasons. were evaluated for a minimum of four years, October 15. In addition, the large leaves except for Vernonia angustifolia ‘Plum were sometimes tattered by strong winds, Maintenance practices were kept to a min- Peachy’, which died during the second especially on the upper half of the stems. imum, thereby allowing the plants to thrive winter in two different trials, and V. novebo- or fail under natural conditions. Trial beds racensis ‘White Lightning’, which had been The soft, needle-shaped leaves of Vernonia were irrigated via overhead sprinklers as in the garden for only three years when the lettermannii ‘Iron Butterfly’ had a similar needed, mulched with composted leaves trial was terminated in autumn 2018. feathery appearance to another Arkansas once each summer, and regularly weeded. native—spring-blooming blue star (Amso- Moreover, plants were not deadheaded, nia hubrichtii)—rather than to any of the fertilized, winter mulched, or chemically Top-rated Ironweeds other ironweeds. ‘Iron Butterfly’ originated Vernonia gigantea ssp. gigantea ‘Jones- treated for insects or diseases. Plants were in the University of Georgia’s trial garden, boro Giant’ was the largest ironweed in the cut back to near the base in late winter be- and was selected for its vigorous growth, trial, reaching 144 inches tall and 60 inches fore new growth began. compact habit, and floriferous nature. At 33 wide. ‘Jonesboro Giant’ differed from the inches tall, ‘Iron Butterfly’ was 10 inches subspecies in being significantly taller and shorter than the species and had a tighter narrower in habit, and flowering seven to habit. Otherwise, the purple flowers were ten days earlier. The rigid stems were up- the same color and size as the species, right at all times, although the plants re- and both taxa were equally floriferous. ‘Iron laxed a bit in October during peak bloom.

Plant Evaluation Notes | chicagobotanic.org | 4 Vernonia 'Summer's Swan Song'

Butterfly’ was less prone to opening up in Vernonia ‘Summer’s Surrender’ is a hybrid der’ was 48 inches tall and 74 inches wide the center in heavy rainfall but was not un- cross of V. lettermannii and V. arkansana with a densely broad habit after five years, touched by this issue; damage was always made by Jim Ault, Ph.D., at the Chicago and it had a passing resemblance to more significant on the species, which was Botanic Garden in 2010. It inherited the ‘Southern Cross’. From early September to also less likely to rebound than ‘Iron Butter- bushy habit of V. lettermannii and the larger early October, dark purple florets, packed fly’. Powdery mildew and rust were never plant size and capitula of V. arkansana; the into 1-inch-wide flower heads, were gener- observed on ‘Iron Butterfly’ or the species. olive-green linear leaves—5 inches long ously produced in airy inflorescences. These taxa were the latest of the ironweeds and ½ inch wide—were intermediate be- ‘Summer’s Surrender’ was resistant to to emerge in the spring. tween the two species. ‘Summer’s Surren- powdery mildew and rust.

Table 1: Weather Summary for 2012-2018 2012 2013 2014 2015 2016 2017 2018

Lowest temperature °F (°C) 2(-17) -3(-19) -16(-27) -13(-25) -4(-20) -5(-21) -8(-22) Lowest temperature date 1/21 1/22 1/6 2/28 1/18 12/27 1/1 Number of days below 0°F (-18°C) 0 3 24 17 13 5 9 Highest temperature °F (°C) 105(41) 96(35) 91(33) 94(34) 95(35) 95(35) 97(36) Highest temperature date 7/5 7/18 7/17 7/17 7/24 6/12 6/30 Number of days above 90°F (32°C) 40 15 5 13 17 16 23 Last frost date 4/24 4/20 4/16 4/24 5/15 4/1 4/29 First frost date 10/6 10/22 10/19 10/17 12/12 11/6 10/13 Number of growing season daysa 165 185 186 176 181 166 167 Annual rainfall in inches (cm)b 31.1(78.9) 39.1(99.3) 42.5(107.9) 43.6(110.7) 36(91.4) 47.6(120.9) 54(137.2) Annual snowfall in inches (cm)c 23.4(59.4) 40.3(102.4) 66.4(168.7) 45.5(115.6) 27(65.6) 17.2(43.7) 34(86.4) aNormal growing season: 165 days bAverage rainfall: 37.7 inches (95.7 cm) cAverage snowfall: 36 inches (91.4 cm)

Data collected at Chicago Botanic Garden weather station Latitude: 41°51’N. Longitude: 87°37’W. Altitude: 578.74 ft. (176.4 m)

Plant Evaluation Notes | chicagobotanic.org | 5 phyllaries

disk floret

capitulum

Vernonia glauca

Vernonia ‘Summer’s Swan Song’ is a hy- Other Ironweeds in the Trial decline in health, rust and powdery mildew brid created by Dr. Ault’s crossing of V. let- The remaining ironweeds varied in their are obligate parasites that require living termannii and V. angustifolia ‘Plum Peachy’. performances, due primarily to habit quali- plants to grow on, so they seldom kill their Similar in bushiness and fine texture to ‘Iron ty, flower production, and/or disease prob- hosts. Butterfly’, ‘Summer’s Swan Song’ is a lems, rather than issues related to cultural slightly larger plant that resists lodging be- adaptability or winter hardiness. Suscepti- Vernonia angustifolia ‘Plum Peachy’, a se- cause of its elongated floral branches; the bility to foliar diseases was the main reason lection of a southern species native from interlocking of the floral branches is a for lower ratings. Both powdery mildew and North Carolina to Mississippi, proved to be unique trait that helps hold stems upright foliar rust were commonly observed, initial- marginally cold-hardy in Zone 5b. Although on rainy days. Deep purple florets in 1-inch ly in mid-August and reaching maximum ‘Plum Peachy’ successfully overwintered in -wide heads were plentiful from early Sep- infection levels of 75 percent to 100 percent two different trials—2010-2012 and 2014- tember to mid-October. The feathery foli- by late September. Rust was far more prev- 2016—the plants died during the second age was moderate to dark olive-green with alent on the majority of ironweeds in all winter in each trial. In the 2014 growing red petioles, up to 5 inches long and less years of the trial; whereas powdery mildew season, plants were bushy, 42 inches tall than a quarter inch wide, and disease-free. was not observed every year and infection and 28 inches wide, with dark red-purple After five years in the trial, ‘Summer’s Swan levels were rarely severe. Rust-infected stems and a purplish tinge to the narrow Song’ measured 36 inches tall and 40 inch- ironweeds appeared to be healthy later into leaves. Violet-purple disk florets, in 1-inch es wide. ‘Summer’s Swan Song’ is hardy in the season because the pustules on the -wide heads, were moderately produced Zone 4, despite the marginal cold-hardi- undersides of the leaves were less notice- from early September to mid-October. ness of ‘Plum Peachy’. able until severely infected leaves began Plants emerged weakly in spring 2015; dropping. Conversely, powdery mildew habits remained spindly and uneven all more readily gave the perception of poor season, and died in the following winter of health because of the visibility of the dis- 2015-2016. Rabbit browsing was a signifi- ease, which ranged from a light dusting to cant problem in 2015; no foliar diseases a grey-white covering on leaf surfaces. were observed. Although infected ironweeds exhibited a

Plant Evaluation Notes | chicagobotanic.org | 6 Vernonia missurica

Long filiform phyllaries, yellowish green and incurved, distinguish Vernonia arkansana (synonym V. crinita) from other species. Purple disk florets, in large heads to 1¼ inches wide, typically bloomed from mid-August to early October on stiffly erect stems. Like many other species in the trial, the plants of V. arkansana were grown from wild-collected seeds; therefore, floral, foliar, and habit traits varied among the plants. The narrow, willow-like leaves—to 7 inches long—were significantly affected by late-season rust and powdery mildew. Although rust was a consistent problem re- sulting in significant defoliation in October of each year, powdery mildew was noted infrequently. Arkansas or curlytop ironweed is native from New York to Kansas and Wisconsin south to Arkansas.

The purple flowers of Vernonia baldwinii were held in loose, flattened inflorescences Vernonia ‘Jonesboro Giant’ from early August to mid-September. Each disk floret featured a conspicuously divided flower production was as profuse as other loose habits. Contrary to expectations, west- and coiled style, and the recurved phyllary ironweeds. The lance-shaped leaves were ern ironweed did not spread or create a colo- scales gave the involucre a barbed appear- rough on the surface and softly hairy on the ny during its seven years in the trial garden. ance. Given the smaller flower heads—less undersides. White hairs clothed the erect This species is native to the Central United than an inch wide—the floral display was stems, which formed robust, if somewhat States—from Minnesota to Texas and Illinois not as vivid as Arkansas ironweed, but

Plant Evaluation Notes | chicagobotanic.org | 7 Vernonia chinensis Vernonia noveboracensis west to Kansas—and is considered more At 103 inches tall, Vernonia gigantea (syn- Pennsylvania to Kentucky and south to Ala- drought-tolerant than other species. onym V. altissima) was the second largest bama and Mississippi. ironweed in the trial. Small flower heads, to Vernonia chinensis was one of several iron- only ½ inch wide, were held in large flat- Vernonia lettermannii had a similar appear- weeds that received lower ratings due to topped panicles from late August to early ance to ‘Iron Butterfly’ and performed disease issues, despite heavy flower pro- October. The purple-violet florets were sur- comparably. The differences between the duction and robust habits. Powdery mildew rounded by purple-brown appressed phyl- species and cultivar were nearly indistin- and rust were regularly observed from Au- laries. Grayish green lance-shaped leaves guishable in the first two years of the trial; gust to October, resulting in significant leaf to 9 inches long were purple-tinged at the however, the species eventually grew larg- drop by late summer. Small heads of light terminals, as were the upper stems. The er—43 inches tall compared to ‘Iron Butter- purple flowers were abundantly produced plant habit was usually robust bushy and fly’ at 33 inches tall—and looser in habit. from mid-August to early October. Long stiffly upright. Foliar diseases were noted in The laxness was particularly evident during lanceolate green leaves were held on erect most years, with rust being a greater prob- the bloom period, when the prodigious green stems. Chinese ironweed did not lem than powdery mildew. Giant ironweed flowers weighted down the stems, expos- stand out ornamentally from other species. and V. gigantea ssp. gigantea were fairly ing the crowns. Heavy rainfall and/or strong similar in habit, plant size, and perfor- winds exacerbated the problem. Despite Vernonia fasciculata featured purple florets mance, except that the slightly larger pur- the propensity to relax, stems were never in dense terminal clusters. The tightly ple florets of the subspecies opened two floppy. As with ‘Iron Butterfly’, no foliar dis- packed flower heads were not as visually weeks later than the species. The species eases were observed. Narrowleaf ironweed impactful compared to species with looser, and subspecies have overlapping ranges is indigenous to western Arkansas and spreading clusters; flower production was throughout Eastern North America. Oklahoma on rocky floodplains, rock out- lower than most other species, too. The crops, and gravel bars. dark green leaves were narrowly lanceo- Vernonia glauca is described as similar to late, serrated, and 5 inches long. Leaves but shorter than V. noveboracensis, which Vernonia missurica was distinctive among were healthy for most of the season until was observed in the trial. The purple-violet the ironweeds for the white pubescence mid-September, when moderate powdery flowers, in 1-inch-wide heads, were abun- that covered the stems and undersides of mildew and rust infections were noted. dant from mid-August to late September. the dark green, lanceolate leaves; the hairy Prairie ironweed’s greatest shortcoming in The large, lance-shaped leaves were dark inflorescences were tinted reddish brown the trial was its weak to floppy habit. Plant green with pale undersides, and remained to purplish. From plump purple buds with centers were routinely open by midsum- healthy until mid-August, when rust and fish scale-like phyllaries, bright magenta mer; many stems would likely have fully powdery mildew were first observed. Se- flowers bloomed from mid-August to Octo- lodged if they had not been held up by vere infections were noted in late Septem- ber. Plants were generally robust, although neighboring plants. Prairie ironweed is na- ber in some but not all years. Plant habits variable in leaf color and plant size; pur- tive to wet prairies, marshes, and ditches were mostly upright but relaxed stems ple-tinged leaves and purple stems were from Manitoba to Oklahoma and west from were occasionally observed. Broadleaf noted in the group. Powdery mildew and Ohio to the Dakotas. ironweed is native to open upland woods, rust were common problems in late Sep- dry and mesic prairies, and roadsides from tember; infection levels typically ranged

Plant Evaluation Notes | chicagobotanic.org | 8 Vernonia trial beds in the Lavin Plant Evaluation Garden from moderate to severe. Missouri iron- was troublesome in the late season. ‘White Summary weed is native to a variety of landscapes Lightning’ was evaluated for only three Ironweeds may be uncommon garden such as mesic prairies, swamps, and along growing seasons. plants but are obvious choices for ecolog- railroads in the central United States. ical and naturalistic landscapes, especially Vernonia ‘Southern Cross’ was selected for pollinator gardens. The sheer number Vernonia noveboracensis had a gangly from seed sown as V. lettermannii by Brent and variety of insects drawn to their pro- habit in its youth, but eventually developed Horvath, Intrinsic Perennial Gardens, He- fuse display of late-season purple flowers a strong bushy habit to 80 inches tall and bron, Illinois. The dark green, willow-like is astonishing. The only plant group with 68 inches wide. From mid-August to late foliage was wider than narrowleaf ironweed greater insect visitation in the Chicago Bo- September, deep purple flowers were with a bronze cast to the terminal leaves tanic Garden’s trials were mountain mints borne in massive inflorescences to nearly 2 and purplish stems. Bright purple flowers, (Pycnanthemum spp.), and in particular, feet across. The dark green, lanceolate in heads to 1 inch across, were plentiful silvery-leaved P. muticum. Ironweeds are leaves were coarse, to 8 inches long, and from mid-August to late September. often overlooked as garden plants due in borne on stiff purplish stems. New York ‘Southern Cross’ was stiffly erect and part to their large size, and perhaps, being ironweed was rust-free during our trial; bushy to 40 inches tall and 33 inches wide native plants, they are not readily available however, severe powdery mildew was after four years. Severe rust was noted in average garden centers. Furthermore, common in late August and September. each year, but plants were mildew-free. the dearth of innovation in breeding and Vernonia noveboracensis is native through- selecting new cultivars has until recently out the eastern United States, from Massa- exacerbated the matter. Fortunately, the chusetts to Florida, on moist sites such as introduction of new compact hybrid culti- floodplains, pond edges, and seeps. ‘White vars, such as ‘Southern Cross’, ‘Sum- Lightning’—a seed strain developed by mer’s Surrender’, and ‘Summer’s Swan Jelitto Perennial Seeds—bloomed the first Song’, has created excitement in the gar- year from seed. Pure white flowers opened dening world. Beyond the strong orna- in mid-August on rigid stems to 70 inches mental attributes, easy culture and adapt- tall and 44 inches wide. The dark green ability to a variety of cultural conditions are leaves were rust-free, but powdery mildew merits of ironweeds.

Plant Evaluation Notes | chicagobotanic.org | 9 Vernonia noveboracensis Vernonia ‘Southern Cross’ courtesy Walters Gardens

Four ironweeds received five-star excellent Rather than relegating ironweeds to native ratings, including Vernonia gigantea ssp. lists and associated landscape uses, con- References gigantea ‘Jonesboro Giant’, V. lettermannii sider that their striking purple flowers bloom Armitage, A.M. 2008. Herbaceous ‘Iron Butterfly’, V. ‘Summer’s Surrender’, at the right time to punch up the late sea- Perennial Plants, Third Edition. Cham- and V. ‘Summer’s Swan Song’. These son garden. Whether tall or short, iron- paign, IL: Stipes Publishing L.L.C. top-rated ironweeds featured superior or- weeds pair well with other late bloomers DiSabato-Aust, T. 2006. The Well-Tended namental traits such as strong vigorous such as sunflowers (Helianthus spp.), gold- Perennial Garden. Portland, OR: Timber habits, handsome foliage, heavy flower enrods (Solidago spp.), and asters (Sym- Press, Inc. production, winter hardiness, and disease phyotrichum spp.), as well as ornamental resistance. Foliar diseases plagued the re- grasses such as big bluestem (Andropogon Gleason, M.L., Daughtrey, M.L., Chase, mainder of the ironweeds and were the gerardii), Indiangrass (Sorghastrum nu- A.R., Moorman, G.W., and Mueller, D.S. most common cause for lower ratings. tans), and switchgrass (Panicum virgatum). 2009. Diseases of Herbaceous Perenni- Amassing a plant group such as ironweeds While the issue of diseases cannot be ig- als. St. Paul, MN: APS Press. in a common location is atypical of how nored, the ornamental merits and pollinator Rice, G., editor-in-chief. 2006. American these plants would be grown, so the prolif- appeal of ironweeds may outweigh these Horticultural Society Encyclopedia of eration of a particular disease such as rust potential troubles for some gardeners. Perennials. New York, NY: DK Publishing, or powdery mildew may not be a natural Inc. occurrence in every landscape. Cold hardi- ness was not an issue for the ironweeds, except for ‘Plum Peachy’, which is a selec- tion of the southern species V. angustifolia. In the case of ‘Plum Peachy’, issues with soil moisture may have played a part in its winter loss as much as cold temperatures.

Plant Evaluation Notes | chicagobotanic.org | 10 Table 2: Observed plant traits and performance ratings Overall Flower Flower Bloom Flower Plant Plant Powdery Rating1 Vernonia Color Size2 Period Production Height Width Rust Mildew HH V. angustifolia ‘Plum Peachy’ violet-purple 1 in. early September to mid-October fair 42 in. 28 in. none observed none observed HHHH V. arkansana purple 1¼ in. mid-August to early October excellent 72 in. 55 in. yes yes HHHH V. baldwinii purple ¾ in. early August to mid-September excellent 68 in. 50 in. yes yes 5 HHH V. chinensis light purple /8 in. mid-August to early October excellent 84 in. 50 in. yes yes HHH V. fasciculata purple ¾ in. late August to late September good 67 in. 72 in. yes yes HHHH V. gigantea purple-violet ½ in. late August to early October excellent 103 in. 65 in. yes yes HHHH V. gigantea ssp. gigantea purple ¾ in. mid-September to late October excellent 100 in. 70 in. yes yes HHHHH V. gigantea ssp. gigantea ‘Jonesboro Giant’ purple ¾ in. late September to early Nov excellent 144 in. 60 in. none observed yes HHH V. glauca purple-violet 1 in. mid-August to late September excellent 72 in. 64 in. yes yes HHHH V. lettermannii purple ½ in. mid-September to mid-October excellent 43 in. 48 in. none observed none observed HHHHH V. lettermannii ‘Iron Butterfly’ purple ½ in. mid-September to late October excellent 33 in. 54 in. none observed none observed HHHH V. missurica bright magenta 1 in. mid-August to early October excellent 74 in. 64 in. yes yes HHH V. noveboracensis dark purple 1 in. mid-August to late September excellent 80 in. 68 in. none observed yes HHHH V. noveboracensis ‘White Lightning’ white ¾ in. mid-August to late September good 70 in. 44 in. none observed yes HHHH V. ‘Southern Cross’ bright purple 1 in. mid-August to late September excellent 40 in. 33 in. yes yes HHHHH V. ‘Summer’s Surrender’ dark purple 1 in. early September to early October excellent 48 in. 74 in. none observed none observed HHHHH V. ‘Summer’s Swan Song’ dark purple 1 in. early September to mid-October excellent 36 in. 40 in. none observed none observed 1Overall Rating: HHHHH excellent, HHHH good, HHH fair, HH poor, H very poor 2Flower Size: width of a single flower head or capitulum