''Silphium laciniatum'' is a species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

in the family

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

known commonly as compassplant or compass plant. It is native to North America, where it occurs in

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...

in Canada and the eastern and central United States as far west as

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

. Other common names include prairie compass plant,Zhang, H., et al. (1991)
Development of leaf orientation in the prairie compass plant, ''Silphium laciniatum'' L.
''Bulletin of the Torrey Botanical Club'' 118(1) 33-42. pilotweed, polarplant, gum weed, cut-leaf silphium, and turpentine plant.Wynia, R. 2009
Plant Fact Sheet for compassplant (''Silphium laciniatum'' L.).
USDA NRCS, Kansas Plant Materials Center, Manhattan, Kansas. 2009. It is a rosinweed of genus '' Silphium''.

Description

This plant is a taprooted perennial

herb In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal ...

producing rough-haired stems usually one to three meters tall. The leaves are variable in shape and size, being long and wide. They are hairy, smooth-edged or toothed, and borne on petioles or not. The back of the flower head has layers of rough, glandular phyllaries. The head contains 27 to 38 yellow ray florets and many yellow disc florets. The fruit is a cypsela which can be almost long and is tipped with a pappus of two short awns.

Biology

The common name compass plant was inspired by the "compass orientation" of its leaves. The large leaves are held vertically with the tips pointing north or south and the upper and lower surfaces of the blades facing east or west. A newly emerging leaf grows in a random direction, but within two or three weeks it twists on its petiole clockwise or counterclockwise into a vertical position. Studies indicate that the sun's position in the early morning hours influences the twisting orientation. This orientation reduces the amount of solar radiation hitting the leaf surface.''Silphium laciniatum''.
Missouri Botanical Garden. Vertical leaves facing east-west have higher water use efficiency than horizontal or north-south-facing blades.Jurik, T. W., et al. (1990)
Ecophysiological consequences of non-random leaf orientation in the prairie compass plant, ''Silphium laciniatum''.
''Oecologia'' 82(2), 180-86. Early settlers on the

Great Plains The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, an ...

could make their way in the dark by feeling of the leaves. An early, (if not the earliest) descriptive naming of the compass plant is found in the 1843 hunting trip of William Clark Kennerly, who upon leaving Westport Kanasas in May 1843, observed the plant and began its description in his trip: "Westward we went, and still westward, through a flat, arid country with no verdure except the compass plant, which we named for the reason that its large, flat leaves always pointed north and south".

Ecology

Surveys of the insect fauna on typical compass plants have noted many different taxa, often present in large numbers. One plant can produce up to 12 stems. Surveys counted an average of nearly 80 insects on each stem or within its tissues. The vast majority of insects on the stems are the

gall wasp Gall wasps, also incorrectly called gallflies, are hymenopterans of the family Cynipidae in the wasp superfamily Cynipoidea. Their common name comes from the galls they induce on plants for larval development. About 1,300 species of this generall ...

s '' Antistrophus rufus'' and '' A. minor'', and the many types of

parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

s that attack them.Tooker, J. F. and L. M. Hanks. (2004)
Endophytic insect communities of two prairie perennials (Asteraceae: ''Silphium'' spp.).
''Biodiversity & Conservation'' 13(13), 2551–66. The gall wasps, especially ''A. rufus'', inject eggs into the stem, an action that induces the formation of a

gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to be ...

in the plant tissue. The

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

of the wasp lives and feeds inside the gall, overwinters there, and emerges as an adult the following spring.Tooker, J. F., et al. (2005)
Plant volatiles are behavioral cues for adult females of the gall wasp ''Antistrophus rufus''.
''Chemoecology'' 15(2), 85-88. Over 600 galls can be in a single stem.Tooker, J. F. and L. M. Hanks. (2006)
Tritrophic interactions and reproductive fitness of the prairie perennial ''Silphium laciniatum'' Gillette (Asteraceae).
''Environmental Entomology'' 35(2), 537-45. The galls are internal in this species, and generally not visible. The adult female ''A. rufus'' locates an appropriate site to oviposit by detecting plant volatiles emitted by the fresh growing stem of its host plant, a mix of

monoterpene Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16. Monoterpenes may be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen funct ...

s. The male ''A. rufus'' also uses the volatiles in his search for mates. Females mate immediately upon emergence from the gall, and the male uses volatiles to find a gall containing a female, as evidenced by the movements of his antennae upon the plant's surface. He then waits there for her to emerge.Tooker, J. F., et al. (2002)
Altered host plant volatiles are proxies for sex pheromones in the gall wasp ''Antistrophus rufus''.
''Proceedings of the National Academy of Sciences'' 99(24), 15486-91. Other insects found in the plant include several species of

parasitoid wasp Parasitoid wasps are a large group of hymenopteran superfamilies, with all but the wood wasps (Orussoidea) being in the wasp-waisted Apocrita. As parasitoids, they lay their eggs on or in the bodies of other arthropods, sooner or later causin ...

s that attack ''A. rufus'' larvae in the galls, the two most common being '' Eurytoma luta'' and '' Ormyrus labotus''. Others include '' Eupelmus vesicularis'' and species of the genera '' Brasema'' and '' Homoporus''. The

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

'' Mordellistena aethiops'' lives on the plant, its larvae boring into the stems, and it is attacked by parasitoid wasps of the genera '' Schizopyramnus'', ''

Heterospilus ''Heterospilus'' is a genus of braconid wasps in the family Braconidae. There are at least 130 described species in ''Heterospilus''. See also * List of Heterospilus species, List of ''Heterospilus'' species File:Heterospilus eurostae female. ...

'', and ''

Tetrastichus ''Tetrastichus'' is a genus of hymenopteran insects of the family Eulophidae. ''Tetrastichus planipennisi'' is a parasitoid of the emerald ash borer, a wood boring insect native to Asia which is an invasive species in North America. ''T. planip ...

''. Many birds and mammals feed on the fruits of the plant. The eastern kingbird perches on the tall plant to watch for insect prey.

Livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animals ...

find it palatable.

Uses

The plant had a variety of uses among Native American groups. The bitter,

resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on natu ...

ous

sap Sap is a fluid transported in xylem cells (vessel elements or tracheids) or phloem sieve tube elements of a plant. These cells transport water and nutrients throughout the plant. Sap is distinct from latex, resin, or cell sap; it is a separa ...

could be made into a chewing gum.''Silphium laciniatum''.
Native American Ethnobotany. University of Michigan, Dearborn. The Pawnee made a tisane with it. Many groups burned the dried root as a

charm Charm may refer to: Social science * Charisma, a person or thing's pronounced ability to attract others * Superficial charm, flattery, telling people what they want to hear Science and technology * Charm quark, a type of elementary particle * Ch ...

during

lightning Lightning is a naturally occurring electrostatic discharge during which two electric charge, electrically charged regions, both in the atmosphere or with one on the land, ground, temporarily neutralize themselves, causing the instantaneous ...

. The plant is cultivated in gardens.

Literature

In 1882 Benjamin Alvord reviewed the literature on the plant and offered his observations. In the environmental classic, ''A Sand County Almanac'',

Aldo Leopold Aldo Leopold (January 11, 1887 – April 21, 1948) was an American writer, philosopher, naturalist, scientist, ecologist, forester, conservationist, and environmentalist. He was a professor at the University of Wisconsin and is best known for his ...

devotes much of the July entry to ''Silphium''—its hardiness, but its slow disappearance nevertheless, a harbinger of the fate of the prairie. "It is easy now to predict the future. For a few years my Silphium will try in vain to rise above the mowing machine, and then it will die. With it will die the prairie epoch."

References

External links

* * *
Plants of Wisconsin

* {{Taxonbar, from=Q1780806 laciniatum Flora of the Eastern United States Flora of Ontario Flora of New Mexico Flora of the United States Plants used in traditional Native American medicine Plants described in 1753 Taxa named by Carl Linnaeus