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|Fred Nation, Atlas of Florida Vascular Plants|
In Canada, sundial lupine occurs in Ontario and Newfoundland [20,32]. In the United States it extends from Minnesota and Iowa eastward through the Lake States and New England south through Kentucky, West Virginia, and the Atlantic coast states to northern Florida. From northern Florida its range extends westward to eastern Texas [11,25,32,70].
Lupinus perennis subsp. gracilis occurs in the southern portion of the species's range from Texas east through the Gulf states and north through Atlantic states to Virginia . Lupinus p. subsp. perennis occurs in Ontario, Newfoundland, and the northeastern United States from Minnesota, Iowa and Illinois east to the Atlantic coast and south as far as Georgia. Since infrataxa are not usually distinguished in the literature, they will not be discussed further in this review. Plants Database provides a distributional map of sundial lupine and its subspecies.
The following lists are based on sundial lupine distribution information and the habitat characteristics and plant species composition of vegetation communities sundial lupine is known to occupy. There is not conclusive evidence that wild lupine occurs in all the habitat types listed, and some community types may have been omitted.ECOSYSTEMS :
|Drew Feldkirchner, Wisconsin Department of Natural Resources|
Sundial lupine is a long-lived, cool-season, nitrogen-fixing forb with a thick, deep taproot [8,25,64]. The fine roots only survive about 4 weeks . According to reviews and a gardening guide, sundial lupine is rhizomatous [11,22,64]. In a comprehensive review of the information available on sundial lupine rhizomes, Girgore and others  note that the perennating buds of this native perennial can be found 0 to 4 inches (0-10 cm) below the soil surface. Sundial lupine grows 8 to 24 inches (20-60 cm) tall and has palmately compound leaves with 7 to 11 leaflets from 0.6 to 2.4 inches (1.5-6 cm) long. The perfect flowers are bilabiate. Petals up to 0.6 inch- (1.6 cm) long occur on erect racemes. After pollination, a 1.2- to 2-inch (3-5 cm) legume pod forms [19,52]. From information in the literature, Halpern  reports that pod may contain up to 7 seeds. Average seed mass is typically between 27 and 28 mg [23,83]. The seed mass of 5,839 seeds from 59 plants ranged from 8 to 41 mg .
RAUNKIAER  LIFE FORM:
According to reviews, sundial lupine reproduces by production of ramets from rhizomes and germination from seed [11,16,22,26,71].
Pollination: Reviews list honey bees, bumble bees, eastern carpenter bees, and butterflies including black swallowtails, clouded sulphurs, and Karner blues as pollinators of sundial lupine [11,26]. Beetles, ants, and thrips may also pollinate sundial lupine .
Breeding system: Sundial lupine is monoecious . Although wild lupine can self-pollinate, most breeding occurs through cross-pollination. Self-pollinated flowers yield significantly (p≤0.0002) less fruit and seed per inflorescence and have more aborted seeds per fruit .
Seed production: Sundial lupine may begin flowering in its 2nd year, but likely starts later in mediocre conditions [40,66,82]. It may not sprout every year. Sundial lupines produced as many as 52 pods on 7 flowering stalks . In west-central Wisconsin, Maxwell  observed increased flowering in cooler years. Number of seeds per inflorescence in self pollinated sundial lupine was 40% to 60% (p<0.0001) less than outcrossed seeds . The 3 highest seed yields of 4-year-old sundial lupine on planted sites in Wisconsin were :
|Clean seeds/acre (lbs)||Seeds/lb (#)||Soil texture on the site|
|189||22,100||Moderately fertile loam|
|159||23,900||Moderately fertile loamy sand|
Seed dispersal: According to reviews, seed dispersal only occurs by dehiscence of the seed pod [11,22,26]. Seeds can be thrown from 3 feet (1 m)  to 16.4 feet (5 m) from the plant .
Seed banking: Based on the literature, Halpern  reports sundial lupine seeds may germinate the summer they mature or remain dormant in the seed bank for at least 3 years.
Germination: Sundial lupine seeds germinate in varying conditions. In the laboratory Mackay and others  found similar germination after 72 hours in seeds germinated in light and dark conditions. Zaremba and Pickering  observed germination throughout the year in the Albany Pine Bush of New York. However, higher germination was observed in sundial lupine seeds planted in spring (59%) compared to those planted in fall (39%) .
Some scarification methods improve sundial lupine seed germination compared to unscarified seeds, while others do not [12,22,46]. In an experiment to determine the effects various scarification treatments, 72% of seeds in the untreated group germinated over an unspecified time period. Seeds scarified with hot water exhibited an insignificant (p>0.05) decline in percent germination (57%), while those tumble scarified with pea gravel for 2 to 3 hours showed an insignificant increase (89%). Mechanical scarification using a commercial scarifier that threw seed against an abrasive drum resulted in significant (p<0.05) declines in percent germination (52%) . After 1 week Mackay and others  reported less than 15% germination of unscarified wild lupine seeds, while percent germination of seeds scarified in sulfuric acid was about 90% for seeds soaked 15 minutes and approached 100% for seeds soaked ≥30 minutes. Seeds nicked using a razor blade exhibited 100% germination. Soaking sundial lupine seeds in water of varying temperatures (72-212 °F (22-100 °C)) did not promote germination . Exposure to fire may result in large decreases in percent germination. After 90 days, Grigore and Tremer  found significantly (p<0.001) lower percent germination in seeds on the surface of prescribed burned sites compared to buried and unburned seeds (see Discussion and Qualification of Plant Response).
Water availability affects percent germination. For instance, seeds that received 11 inches (28 cm, ambient) or 14 inches (35 cm, wet) of water over 3 months exhibited 92% germination, while only 62% of seeds limited to 2 inches (6 cm, dry) of water germinated. In addition, the effect of seed mass on germination varied with water availability. The probability of germination increased 3-fold with a 10-mg increase in seed mass in seeds exposed to ambient or wet conditions, while seeds in dry conditions did not show increased germination with increased seed size. In addition, the decrease in time to germination due to increased seed mass was larger in the ambient and wet treatments than in the dry treatment .
Temperature can also influence germination. Seeds collected in southern Ontario and stored in a freezer for 6 weeks exhibited significantly (p<0.05) higher germination after 4.5 months (99%) than those stored at room temperature (62%) . In addition, at least 2 studies have cold-stratified sundial lupine seeds before experimentation [26,83]. However, percent germination of both cold-treated (near freezing for 71 days) and control seeds collected in southern New England was 41% . Zaremba and Pickering  also report germination without a cold treatment. Sundial lupine seeds scarified in sulfuric acid exhibited decreased percent germination at high temperatures. From 70 to 85 °F (21-29°C), more than 80% of scarified seeds germinated within 54 hours. Percent germination was about 60% in scarified seeds in the 90 °F (32 °C) treatment and less than 4% in the ≥95 °F (35 °C) treatments .
Partial predation of seeds may reduce germination. In a laboratory study where predation was simulated by removing 30% or 60% of seed reserves, control seeds exhibited 80% emergence rates, while ≤50% of treated seeds emerged .
Seedling establishment/growth: Seedling survival of sundial lupine is typically low. In New York, only 327 seedlings out of 1,235 germinated seeds survived their 1st winter . In northwestern Ohio the highest mortality on unburned oak savanna sites was 40% . In southern Ontario, only 20% of seeds planted and germinated in 1990 sprouted in 1991. In addition to predation, mortality of these and other seedlings in the area was due to desiccation, frost, and possibly shading. Increased amounts of litter and species competing for light and other resources may also reduce sundial lupine establishment .
Mortality of lupine seedlings subjected to fire is high. Within 2 months of prescription burning in oak (Quercus spp.) savanna of northwestern Ohio, 95% of lupine seedlings on 1 site and 100% on another site died. The effect of these burns on seedlings that emerged after the fire is less clear. On 1 of 3 sites, lupine seedling survival was significantly (p<0.01) lower in burned areas than in unburned areas. The site had not been burned for 10 years before the experimental fire, while the 2 sites where sundial lupine seedling survival on burned and unburned areas did not differ (p>0.1) had been burned ≤2 years prior to the experimental fires .
Sundial lupine seedlings germinated from large seeds may have a better chance of surviving, at least in the short term, than seedlings from small seeds. Survival of seedlings to July was doubled with a 10-mg increase in seed mass, and larger seeds were related to greater plant size in years 1 and 2 .
In a simulated herbivory experiment, sundial lupine seedlings subjected to 60% removal of seed reserves were significantly (p<0.05) shorter, had smaller leaf areas, and had lower dry weight than control seeds or those subject to 30% removal of seed reserves .
Asexual regeneration: According to reviews, a sundial lupine rhizome can produce several shoots that form clumps. Ramets may be over 3 feet (1 m) from the genet, which can make identification of individual plants difficult [22,26,71].SITE CHARACTERISTICS:
Sundial lupine typically occurs in well-drained, sandy soils with slightly acidic pH. Sundial lupine's occurrence in sandy soil has been widely reported [9,26,64,68]. In southern Wisconsin, sites with sundial lupine typically had more than 80% sand . Sundial lupine has also been reported on neutral to strongly acidic soils [33,82]. In the Albany Pine Bush of New York, soils where lupine was growing had an average pH of 5.3. This was a higher pH than found at sites throughout the Albany Pine Bush (x pH=4.8) . At the Allegan State Game Area in Michigan sundial lupine was found in soils with pH ranging from 4.2 to 5.6 . A review states that sundial lupine grows in basic conditions in the Finger Lakes region of New York .
Sundial lupine may occur at higher frequencies on sites with disturbed soil [37,39,47]. In west-central Wisconsin, a flush of seedlings was documented after vehicular traffic disturbed the soil in a closed stand. In the same study area, experimental seeded sites prepared by grubbing trees, tilling, and herbicide application had significantly (p<0.0001) higher frequency of flowering and nonflowering lupine combined (65%) than undisturbed quadrats (40%). The author calls for more research into the importance of soil disturbance to sundial lupine . In Minnesota, sites associated with steep sand banks that experience sloughing were the only areas of dense wild lupine . According to a review, reductions in soil disturbance may be a cause of sundial lupine decline . However, another review lists "excessive" soil disturbance as a possible cause for sundial lupine decline .
Little information is available regarding other characteristics of wild lupine sites, such as elevation or precipitation. Sundial lupine is included in a commercially available seed mixture meant for planting above 7,000 feet (2,000 m) . Forrester and others  investigated sundial lupine in eastern New York on sites from 200 to 400 feet (60-120 m) elevation that received average annual precipitation of 37 inches (930 mm). A site with sundial lupine in southern Wisconsin receives average annual precipitation of 34 inches (858 mm), of which a 3rd typically falls during the peak of sundial lupine's growing season . A seed catalog recommends 12 inches (300 mm) of precipitation for sundial lupine .SUCCESSIONAL STATUS:
For information on the effects of canopy cover on the quality of sundial lupine as a Karner blue butterfly resource see Preferred Habitat in the FEIS review of Karner blue butterfly.SEASONAL DEVELOPMENT:
Surviving sundial lupine, emerging seedlings, and wild lupine adjacent to a burn may provide sources for secondary colonization of a burned area. However, given sundial lupine's short dispersal distances, colonization from nearby areas would likely take a considerable amount of time, especially in large burned areas.
Fire regimes: According to reviews, sundial lupine typically occurs in habitats subject to fairly frequent fires [11,55,71]. Fire season in areas with sundial lupine varies from dormant-season to early and late-growing season fires. Fire regimes where sundial lupine occurs are influenced by several factors including habitat, historical period, and weather conditions [15,79]. Information regarding fire regimes in sundial lupine habitats such as savannas [7,44,79] and pitch pine (Pinus rigida) barrens [15,42,45,48] is available.
The following table provides fire return intervals for plant communities and ecosystems where sundial lupine may occur. Find fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find Fire Regimes".
|Community or Ecosystem||Dominant Species||Fire Return Interval Range (years)|
|bluestem prairie||Andropogon gerardii var. gerardii-Schizachyrium scoparium||<10 [35,50]|
|jack pine||Pinus banksiana||<35 to 200 [6,13]|
|shortleaf pine||Pinus echinata||2-15|
|shortleaf pine-oak||Pinus echinata-Quercus spp.||<10|
|sand pine||Pinus elliottii var. elliottii||25-45|
|longleaf pine-scrub oak||Pinus palustris-Quercus spp.||6-10 |
|red pine (Great Lakes region)||Pinus resinosa||3-18 (x=3-10) [5,17]|
|red-white pine* (Great Lakes region)||Pinus resinosa-P. strobus||3-200 [6,28,43]|
|pitch pine||Pinus rigida||6-25 [4,29]|
|eastern white pine||Pinus strobus||35-200|
|eastern white pine-northern red oak-red maple||Pinus strobus-Quercus rubra-Acer rubrum||35-200|
|loblolly pine||Pinus taeda||3-8|
|loblolly-shortleaf pine||Pinus taeda-P. echinata||10 to <35|
|Virginia pine||Pinus virginiana||10 to <35|
|Virginia pine-oak||Pinus virginiana-Quercus spp.||10 to <35|
|northeastern oak-pine||Quercus-Pinus spp.||10 to <35|
|southeastern oak-pine||Quercus-Pinus spp.||<10|
|white oak-black oak-northern red oak||Quercus alba-Q. velutina-Q. rubra||<35|
|northern pin oak||Quercus ellipsoidalis||<35|
|bear oak||Quercus ilicifolia||<35|
|bur oak||Quercus macrocarpa||<10 |
|oak savanna||Quercus macrocarpa/Andropogon gerardii-Schizachyrium scoparium||2-14 [50,74]|
|chestnut oak||Quercus prinus||3-8|
|post oak-blackjack oak||Quercus stellata-Q. marilandica||<10|
|black oak||Quercus velutina||<35 |
Sundial lupine abundance is typically unaffected by fire. In oak (Quercus spp.) savannas of central Wisconsin, sundial lupine percent cover did not exhibit a significant (p>0.1) response to prescribed fires conducted in July or November . In upland vegetation in northwestern Wisconsin that was burned under prescription, sundial lupine frequency increased an average of 1.1% on burned sites, a "neutral" response . On oak savanna burned under prescription in northwestern Ohio, sundial lupine exhibited an insignificant (p=0.16) increase in percent cover compared to unburned areas . In west-central Wisconsin, prescribed fires in the fall of 1993 and spring of 1994 had little effect on wild lupine frequency, suggesting the fires did not reduce dormancy or increase seedling recruitment. In the year following prescribed burning, however, nonflowering (p<0.01) and flowering (p<0.05) sundial lupine on burned sites experienced significantly less decline than sundial lupine on unburned sites. Statistical analysis suggested increases in sundial lupine in later years were due to reasons other than burning. The following table shows the number of nonflowering and flowering lupine plants in burned and control plots from 1993 to1995 and 1997 .
|Nonflowering sundial lupine||Flowering sundial lupine|
|<1 postfire year||895||723||1485||1168|
|<2 postfire years||1079||1122||892||667|
|<4 postfire years||1318||1209||1950||1653|
Time since last fire may influence sundial lupine's response. For example, the differing responses of wild lupine seedlings on the 3 sites in northwestern Ohio (see Discussion and Qualification of Plant Response) may have been related to time since last burning. The site where significant differences were observed had not been burned in 10 years, while the sites where no significant differences were observed had been burned within the previous 2 years. The effect of time since burning on fire severity on these sites and/or differences in other site characteristics that may have influenced the response were not discussed .
Fire and site characteristics are likely to influence sundial lupine's response to fire. However, information regarding the impact of these factors is limited. Sundial lupine would likely experience greater detrimental effects when fires are relatively severe and/or perennating buds are located close to the soil surface . Season of burning may influence sundial lupine response. In west-central Wisconsin, cover of sundial lupine differed significantly (p<0.05) between spring and fall fires, with spring fires resulting in a "more favorable" response. Frequency of sundial lupine did not differ significantly between sites burned in fall and those burned in spring . The response of associated vegetation is also likely to influence sundial lupine's response. Prescribed fires in west-central Wisconsin only reduced canopy cover in areas with less than 50% tree canopy that were comprised primarily of pines (Pinus spp.) and multi-stemmed oaks such as black oak and northern pin oak .
It has been suggested that sundial lupine's nitrogen-fixing ability may give it an advantage over other species on burned sites due to nitrogen volatilization during fire and nitrogen loss from thatch burn-off [39,47].FIRE MANAGEMENT CONSIDERATIONS:
Palatability/nutritional value: Mature plants can be toxic to domestic sheep and horses [69,80].
Insects such as beetles, butterflies, and moths feed on sundial lupine [77,82]. According to reviews, sundial lupine is an important larval food source for several butterflies, including the frosted elfin and the federally endangered Karner blue butterfly [2,58].
Mammals have also been reported to feed on sundial lupine. Reviews report deer [22,56,75,82] and several small mammals such as rabbits, woodchucks, and chipmunks [22,82] feeding on sundial lupine foliage. However, meadow voles consistently rejected sundial lupine seeds in a feeding trial .
Herbivory can have negative impacts on sundial lupine. A review implicates white-tailed deer grazing as a factor in sundial lupine decline in the Albany Pine Bush , and excessive spring grazing may cause sundial lupine mortality . Increased grazing pressure by white-tailed deer was considered a concern for sundial lupine in 2 sites in Pinery Provincial Park, Ontario . In northwestern Ohio, "extensive" insect feeding damage was observed in sundial lupine seedlings that initially survived prescribed fires but died by the end of the growing season . In southern Ontario, the majority of sundial lupine seedling mortality on 4 sites was due to predation. Slugs were likely responsible for the significantly (p<0.05) higher seedling mortality found on 1 of these sites . Transplanted and drought-stressed sundial lupine may be more susceptible to damage from herbivory .
It has been suggested that grazing by megafauna such as bison and elk before European contact may have prevented succession of savannas to woodland habitats and thus provided open sites for sundial lupine [47,67].
Cover value: No information is available on this topic.VALUE FOR REHABILITATION OF DISTURBED SITES:
No information is available on this topic.
OTHER MANAGEMENT CONSIDERATIONS:
Literature reviews discuss the threats to and management of sundial lupine and its habitat [11,25,55,71,75].
In addition to prescribed burning, mowing, herbicide application, and/or cutting may be used and, in some cases, are required to maintain or create sundial lupine habitat [16,23,47]. In southwestern Michigan, a combination of mowing and application of herbicide in spring reduced overall vegetative cover, contributing to an increase in sundial lupine recruitment that was observed for 3 years . In rights-of-way in eastern New York, wild lupine populations were larger on herbicide, mowing, and/or cutting treatment plots than in untreated areas .
Direct seedling has increased sundial lupine cover on sites prepared by grubbing trees, tilling, and herbicide application .Swengel  listed plowing, frequent mowing and continuous close-cropped grazing as management practices that are incompatible with maintaining wild lupine.
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