Sandhills Lily

Lilium pyrophilum is narrowly endemic to the Sandhills region of southern Virginia, North Carolina, and northern South Carolina. The most ecologically intact populations occur on military bases in the Carolinas that are carefully managed to ensure the frequent fires that promote this fire-dependent lily; many of these fires are initiated by exploding ordnance.

Its close relative, Lilium superbum, occurs to the west in the upper Piedmont, and is not known from the Sandhills proper. Prior to the description of L. pyrophilum, specimens now assignable to it were masquerading in herbaria as other species, primarily L. michauxii. A. E. Radford et al. (1968) mentioned robust L. michauxii bog plants that resembled L. superbum; these are considered here as L. pyrophilum. Discriminating between Lilium superbum and larger specimens of L. pyrophilum may require reference to several characters. The shorter, blunter, more ascending leaves of L. pyrophilum average fewer per whorl and are grouped in fewer whorls, but overlap with L. superbum is extensive. In L. pyrophilum the whorls with the largest number of leaves are often clustered nearer the ground, and distally the stem bears scattered, appressed leaves, whereas the taller L. superbum displays whorling more or less evenly along the stem, and the few scattered leaves above the whorls are not appressed. Lilium pyrophilum blooms somewhat later than L. superbum, though some overlap occurs. The floral tube of L. pyrophilum is longer because the perianth parts are reflexed farther down their lengths, but this difference is subtle. Hybrids between Lilium michauxii and L. pyrophilum are known and often display the wide petals characteristic of the former species. The manner and frequency of visits by ruby-throated hummingbirds [Archilochus colubris (Linnaeus), family Trochilidae] suggest that this species is involved in pollination of the Sandhills lily. The palamedes swallowtail [Papilio palamedes (Drury), family Papilionidae] also visits and pollinates this species.

Bulbs rhizomatous, occasionally branching dichotomously at 120° from main axis, 2.4–2.8 × 5.2–8.6 cm, 0.3–0.5 times taller than long, 2–3 years’ growth evident as annual bulbs, scaleless sections between these 0.3–2.5 cm; scales unsegmented, longest 1.1–1.9 cm; stem roots absent or sometimes present. Stems 0.6–1.6 m. Buds ± triangular in cross section. Leaves often concentrated proximally, occasionally scattered, usually in 1–12 whorls or partial whorls, 3–11(–15) leaves per whorl, barely to moderately ascending proximally, drooping at tips or not, ascending and appressed distally, 2.3–10.3(–12.2) × 0.8–2.4 cm, 1.6–7.6(–10.3) times longer than wide; blade narrowly elliptic, margins not undulate, apex acute, barely acuminate on distal leaves; veins and margins ± smooth abaxially. Inflorescences racemose, 1–7-flowered. Flowers pendent, not fragrant; perianth Turk’s-cap-shaped; sepals and petals reflexed 1/5–1/4 along length from base, yellow (occasionally pale yellow or yellow-orange) proximally, red-orange or dusky red (occasionally magenta, pinkish, pale orange, or red) distally, spotted magenta, not distinctly clawed, nectaries exposed, forming visible green star (or triangle, when only sepal nectaries are exposed); sepals with 2 parallel, often faint abaxial ridges, 6.7–8.9 × 1.1–1.7 cm; petals 6.3–8.7 × 1.5–2.2 cm; stamens strongly exserted; filaments parallel at first, then widely spreading, diverging 12°–28° from axis; anthers magenta or sometimes purple, 1.1–1.8 cm; pollen rust; pistil 3.4–6.4 cm; ovary 1.5–2.8 cm; style pale green, often spotted purple; pedicel 6.8–16.5 cm. Capsules 2.8–4.7 × 1.5–1.9 cm, 1.7–2.8 times longer than wide. Seeds not counted.

N.C., S.C., Va.

Flowering summer (late Jul--mid Aug).

Streamhead pocosins, sandhill seeps and streamsides, drainages in maintained powerlines; 0--200m.

Overview

Lilium pyrophilum, commonly named the Sandhills lily, is a species of lily from the Sandhills region of the Atlantic Coastal Plain (Gregory et. al., 2010, pg. 198; Skinner and Sorrie, 2002, pg.94). This lily is known to exist in 13 counties across the Carolinas and Virginia in longleaf pine ecosystems (Gregory et. al., 2010, pg. 198). It differs slightly in morphology and requires a more restricted habitat compared to its closest relative, L. superbum (Skinner and Sorrie, 2002, pg. 94). L. pyrophilum has a great reliance on fire as a means of population control for competing species and soil maintenance (Skinner and Sorrie, 2002, pg. 100). Due to its restricted habitat and the high competition with tall woody plants as well as collection by humans, the population of the Sandhills lily has declined significantly (Skinner and Sorrie, 2002, pg. 101).

Etymology

L. pyrophilum’s dependence on fire for habitat maintenance explains the use of the Latin phrase pyrophilum, meaning “fire-loving”, for the species (Skinner and Sorrie, 2002, pg. 97). The vernacular name of Sandhills lily was proposed because of the lily’s habitat and distribution, which is mainly restricted to the Sandhills region of the Carolinas and Virginia (Skinner and Sorrie, 2002, pg. 97).

Morphology

The numerous leaves of L. pyrophilum are thin and pale on the underside and are either elliptic or oblong in shape, measuring between 2.3-12.2 by 0.8-2.4 cm (Skinner and Sorrie, 2002, pg. 97). The leaves are scattered and appear in up to 12 whorls of 3 or more leaves per whorl (Skinner and Sorrie, 2002, pg. 97). Its green stems can reach heights of up to 1.6 meters and are erect and glabrous structures, meaning that they do not have hair or down and are smooth (Skinner and Sorrie, 2002, pg. 97). Adventitious roots, which grow from a separate organ such as the stem or leaves, can appear above the bulb if the plant grows large enough (Skinner and Sorrie, 2002, pg. 97).

Inflorescences, which is the location where the flowers are borne, are terminal and racemose, meaning they occur all along the stem (Skinner and Sorrie, 2002, pg. 97). They have anywhere from 1 to 7 flowers on each inflorescence (Skinner and Sorrie, 2002, pg. 97). The pedicels, or flower stalks, measure 6.8 to 16.5 cm long (Skinner and Sorrie, 2002, pg. 97).

The flowers are bisexual, having both male and female reproductive organs (Skinner and Sorrie, 2002, pg. 97). They are pendant, have a radial shape, and are non-fragrant (Skinner and Sorrie, 2002, pg. 97). The flowers are mainly red-orange or dusky red apically, changing to a more yellow-orange in the centers with a prominently green base (Skinner and Sorrie, 2002, pg. 97). L. pyrophilum flowers in summer from late July to the middle of August, with capsules maturing by late October (Skinner and Sorrie, 2002, pg. 97). The flower’s six tepals (3 sepals and 3 petals) measure 6.3-8.9 by 1.1-2.2 cm while the filaments are normally 4.5-5.9 cm long and are usually pale green (Skinner and Sorrie, 2002, pg. 97).

The capsules are loculicidal, meaning that they split lengthwise to split each locule into two separate parts (Skinner and Sorrie, 2002, pg. 97). They have a constricted base, are not strongly winged and can be over twice as long as they are wide, measuring 2.8-4.7 by 1.3-1.9 cm (Skinner and Sorrie, 2002, pg. 97). The seeds are ranked by six and exhibit a flat 60° wedge shape (Skinner and Sorrie, 2002, pg. 97). They are covered in warts or similar growths, making them verrucose, and are light brown with a darker embryo in the center (Skinner and Sorrie, 2002, pg. 97).

Bulbs of the L. pyrophilum are slow-growing rhizomes that can be either horizontal or elongate in shape, measuring between 2.4-2.8 by 5.2-8.6 cm (Skinner and Sorrie, 2002, pg. 97). Scales, which are modified leaves, are lacking between the 2 or 3 bulb units, which is representative of annual growth (Skinner and Sorrie, 2002, pg. 97). These scales are numerous, fleshy, and starchy and can reach 1.9 cm at its longest point (Skinner and Sorrie, 2002, pg. 97).

Distribution and Habitat

The Sandhills lily ranges from southeastern Virginia to central South Carolina within the Atlantic Coastal Plain, with most populations occurring in the Sandhills region, hence the vernacular name for L. pyrophilum (Gregory et. al., 2010, pg. 198; Skinner and Sorrie, 2002, pg.94). The lily occurs at elevations ranging from 25 to 150 meters (Skinner and Sorrie, 2002, pg. 97). It is almost exclusive to longleaf pine communities and most frequently found in herb- and shrub-dominated side slopes along streamheads and small depression pocosins where competition from tall woody plants is low (Skinner and Sorrie, 2002, pg. 98).

The Sandhills lily best grows in three main wetland communities, these being streamhead pocosins, Sandhill seeps, and Coastal Plain small stream seeps (Gregory et al., 2010, pg. 199). Streamhead pocosins occur along the headwaters of creeks and streams when seepage from other nearby ecotones form rivulets and extending downstream (Skinner and Sorrie, 2002, pg. 99). In the canebreak variant where burns are more frequent and less trees and shrubs exist, there only are small populations of 1 to 5 L. pyrophilum plants (Skinner and Sorrie, 2002, pg. 99). Sandhill seeps are found on slopes where the layer of clay in the soil forces water up to the surface (Skinner and Sorrie, 2002, pg. 99). Due to fire-suppression, true examples of these habitats are rare, and the Sandhills lily is rare in this habitat (Skinner and Sorrie, 2002, pg. 99). Coastal Plain small stream seeps occur in flood-prone areas downstream of streamhead pocosins, and only small populations of 1 to 5 plants exist in these ecotones (Skinner and Sorrie, 2002, pg. 99-100). In a population survey that occurred in 30 of the 73 known locations for the lily in North Carolina and Virginia, L. pyrophilum occurred in 47% of plots in Sandhills seeps, 30% of streamhead pocosins plots, and 10% of the plots in Coastal Plain seeps, with an additional13% in small depression pocosins (Gregory et al., 2010, pg. 201). Seventy percent of these plots (21 sites) were located on state or federal land managed by prescribed burns, and twenty-seven percent occurred where mowing was common, which reduces the population of potential competitors of L. pyrophilum (Gregory et. al., 2010, pg. 201; Skinner and Sorrie, 2002, pg. 100).

The soil that the Sandhills lily grows in has a pH of 3.8-5.0 (Gregory et al., 2010, pg. 202). Sulfur is a key nutrient in highly acidic soil types, and during periods of sulfur deficiencies, the plant suffers (Gregory et al., 2010, pg. 202). In lily-containing plots, sulfur levels were measured to be 15 ppm compared to 11 ppm in plots where lilies were absent (Gregory et al., 2010, pg. 202). It can tolerate a number of soils from organic materials, but not loose sandy soils (Gregory et al., 2010, pg. 202).

Lilium pyrophilum needs fire to keep nutrients in the soil and to eliminate shrubs that act as competition for the lily (Skinner and Sorrie, 2002, pg. 100). The areas where the Sandhills lilies are most plentiful are in areas with prescribed burns, where fires are purposefully set in order to control growth of plants and soil quality (Skinner and Sorrie, 2002, pg. 100). Ordinance from military operations on Fort Jackson in South Carolina have also proved beneficial to the plant’s growth, as it has similar effects as prescribed burns (Skinner and Sorrie, 2002, pg. 100).

Of 42 known extant populations in 12 counties of North Carolina and Virginia, there are approximately 205 individuals (Skinner and Sorrie, 2002, pg. 100). The largest of these populations hold fewer than 10 individuals, and most hold only 1 to 3 plants (Skinner and Sorrie, 2002, pg. 100). However, these are 11 historic populations form before 1990 that occur in 4 additional counties (Skinner and Sorrie, 2002, pg. 100)

Conservation

Just as these lilies have specialized habitats with numerous competitor species, L. pyrophilum is also at risk from human intervention and destruction (Skinner and Sorrie, 2002, pg. 101; Gregory et al., 2010, pg. 199). The populations of these lilies have decreased due to removal, and it is encouraged that these plants be enjoyed by botanists in the field rather than in gardens (Skinner and Sorrie, 2002, pg. 101).

Lilium pyrophilum, the sandhills lily, is a North American species of plant in the lily family. It is endemic to the Sandhills region of southern Virginia, North Carolina and northern South Carolina, in the eastern United States.

Lilium pyrophilum produces a rhizomatous bulbous root system which is occasionally branched. The plant grows to 0.6-1.6 m (*) It has long narrow, slightly pointed leaves arranged in a variable number of whorls around the stem. The leaves may be upright or drooping. The yellow or yellow–orange inflorescence is borne on racemes of 1–7 flowers, they are pendant and not fragrant. The petals can be reddish, reddish–orange, dusky red or magenta towards the tip and marked with magenta spots and turned back in a "turks cap" shape. The anthers are magenta or purple. It blooms from late July to mid–August. Lilium pyrophilum is also named the "Sandhills lily" from its restricted location where it benefits from regular brush fires.

Lilium pyrophilum is botanically related to Lilium superbum, with which it may be confused, and Lilium michauxii with which it can cross-pollinate.

By observations it appears that the ruby-throated hummingbirds (Archilocus colubris) may be involved in the pollination of this flower and the Palamedes swallowtail butterfly also pollinates this lily.