41-446: See List of Asclepias species Asclepias is a genus of herbaceous , perennial , flowering plants known as milkweeds , named for their latex , a milky substance containing cardiac glycosides termed cardenolides , exuded where cells are damaged. Most species are toxic to humans and many other species, primarily due to the presence of cardenolides. However, as with many such plants, some species feed upon milkweed leaves or
82-468: A DNA study indicate that, generally, more recently evolved milkweed species ("derived" in botany parlance) use these preventive strategies less but grow faster than older species, potentially regrowing faster than caterpillars can consume them. Research indicates that the very high cardenolide content of Asclepias linaria reduces the impact of the Ophryocystis elektroscirrha (OE) parasite on
123-405: A vascular strand in the nectary to assist in transport over a longer distance. Pollinators feed on the nectar and depending on the location of the nectary the pollinator assists in fertilization and outcrossing of the plant as they brush against the reproductive organs, the stamen and pistil , of the plant and pick up or deposit pollen . Nectar from floral nectaries is sometimes used as
164-765: A cluster of white, silky, filament-like hairs known as the coma (often referred to by other names such as pappus , "floss", "plume", or "silk"). The follicles ripen and split open, and the seeds, each carried by its coma, are blown by the wind . Some, but not all, milkweeds also reproduce by clonal (or vegetative) reproduction. There are also 12 species of Asclepias in South America, among them: A. barjoniifolia , A. boliviensis , A. curassavica , A. mellodora , A. candida , A. flava , and A. pilgeriana . Milkweeds are an important nectar source for native bees , wasps , and other nectar-seeking insects, though non-native honey bees commonly get trapped in
205-479: A five-paired hood-and-horn structure with the hood acting as a sheath for the inner horn. Glands holding pollinia are found between the hoods. The size, shape and color of the horns and hoods are often important identifying characteristics for species in the genus Asclepias . Pollination in this genus is accomplished in an unusual manner. Pollen is grouped into complex structures called pollinia (or "pollen sacs"), rather than being individual grains or tetrads, as
246-539: A food source for monarch butterfly larvae and some other milkweed butterflies . These plants are often used in butterfly gardening and monarch waystations in an effort to help increase the dwindling monarch population. However, some milkweed species are not suitable for butterfly gardens and monarch waystations. For example, A. curassavica , or tropical milkweed, is often planted as an ornamental in butterfly gardens outside of its native range of Mexico and Central America . Year-round plantings of this species in
287-427: A modified part or a novel structure. The different types of floral nectaries include: Most members of Lamiaceae have a nectariferous disc which surrounds the ovary base and derived from developing ovarian tissue. In most Brassicaceae , the nectary is at the base of the stamen filament. Many monocotyledons have septal nectaries, which are at the unfused margins of the carpels. These exude nectar from small pores on
328-406: A nutrient source to animal mutualists , which in turn provide herbivore protection . Common nectar-consuming pollinators include mosquitoes , hoverflies , wasps , bees , butterflies and moths , hummingbirds , honeyeaters and bats . Nectar plays a crucial role in the foraging economics and evolution of nectar-eating species; for example, nectar foraging behavior is largely responsible for
369-590: A plant-based alternative to down and promote the growth of milkweed in areas where it has declined, though there is some concern that the environmental impacts could be negative if monoculture is used. Asclepias is also known as "Silk of America" which is a strand of common milkweed ( A. syriaca ) gathered mainly in the valley of the Saint Lawrence River in Canada . Milkweed floss can be used in thermal insulation and acoustic insulation. The floss
410-617: A preference for plants with extrafloral nectaries, particularly some species of ants and wasps , which have been observed to defend the plants bearing them. Acacia is one example of a plant whose nectaries attract ants, which protect the plant from other insect herbivores . Among passion flowers , for example, extrafloral nectaries prevent herbivores by attracting ants and deterring two species of butterflies from laying eggs. In many carnivorous plants , extrafloral nectaries are also used to attract insect prey . Charles Darwin understood that extrafloral nectar "though small in quantity,
451-446: A primary food source. In turn, these wasps then hunt agricultural pest insects as food for their young. Nectar is most often associated with flowering plants angiosperms , but it is also produced by other groups, including ferns . Nectar is derived from Greek νέκταρ , the fabled drink of eternal life. Some derive the word from νε- or νη- "not" plus κτα- or κτεν- "kill" , meaning "unkillable", thus "immortal". The common use of
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#1732772997850492-470: A proper K, Ca concentration gradient . As a result, many peoples of South America and Africa used arrows poisoned with these glycosides to fight and hunt more effectively. Some milkweeds are toxic enough to cause death when animals consume large quantities of the plant. Some milkweeds also cause mild dermatitis in some who come in contact with them. Nonetheless, some species can be made edible if properly processed. List of Asclepias species This
533-462: A protective function. The Nicotiana attenuata , a tobacco plant native to the US state of Utah , uses several volatile aromas to attract pollinating birds and moths. The strongest such aroma is benzylacetone , but the plant also adds bitter nicotine , which is less aromatic, so may not be detected by the bird until after taking a drink. Researchers speculate the purpose of this addition is to discourage
574-433: A reward to insects, such as ants , that protect the plant from predators. Many floral families have evolved a nectar spur . These spurs are projections of various lengths formed from different tissues, such as the petals or sepals. They allow for pollinators to land on the elongated tissue and more easily reach the nectaries and obtain the nectar reward. Different characteristics of the spur, such as its length or position in
615-582: Is a list of species in the flowering plant genus Asclepias . As of February 2024 , Plants of the World Online accepts 204 species in Asclepias . A B C D E F G H I J K L M N O P Q R S T U V U W X Y Z Nectar Nectar is a viscous , sugar -rich liquid produced by plants in glands called nectaries , either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries , which provide
656-470: Is also highly buoyant and water-repellent, but absorbs oil readily. Due to its oil-absorbing properties, it can be used for oil spill cleanup. Milkweed latex contains about two percent latex, and during World War II both Nazi Germany and the US attempted to use it as a source of natural rubber , although no record of large-scale success has been found. Many milkweed species also contain cardiac glycoside poisons that inhibit animal cells from maintaining
697-912: Is greedily sought by insects" but believed that "their visits do not in any way benefit the plant". Instead, he believed that extrafloral nectaries were excretory in nature ( hydathodes ). Their defensive functions were first recognized by the Italian botanist Federico Delpino in his important monograph Funzione mirmecofila nel regno vegetale (1886). Delpino's study was inspired by a disagreement with Darwin, with whom he corresponded regularly. Extrafloral nectaries have been reported in over 3941 species of vascular plants belonging to 745 genera and 108 families , 99.7% of which belong to flowering plants (angiosperms), comprising 1.0 to 1.8% of all known species. They are most common among eudicots , occurring in 3642 species (of 654 genera and 89 families), particularly among rosids which comprise more than half of
738-430: Is most often suggested to grow milkweeds that are native to the geographical area they are planted in to prevent negative impacts on monarch butterflies. Monarch caterpillars do not favor butterfly weed ( A. tuberosa ), perhaps because the leaves of that milkweed species contain very little cardenolide . Some other milkweeds may have similar characteristics. Milkweeds are not grown commercially in large scale, but
779-499: Is particularly rich in carbohydrates, proteins and lipids. While their function is not always clear, and may be related to regulation of sugars, in most cases they appear to facilitate plant insect relationships. In contrast to floral nectaries, nectar produced outside the flower generally has a defensive function. The nectar attracts predatory insects which will eat both the nectar and any plant-eating insects around, thus functioning as "bodyguards". Foraging predatory insects show
820-431: Is typical for most plants. The feet or mouthparts of flower-visiting insects , such as bees , wasps , and butterflies , slip into one of the five slits in each flower formed by adjacent anthers . The bases of the pollinia then mechanically attach to the insect, so that a pair of pollen sacs can be pulled free when the pollinator flies off, assuming the insect is large enough to produce the necessary pulling force (if not,
861-1216: Is variable due to many factors, including flower age, plant location, and habitat management. Extrafloral nectaries (also known as extranuptial nectaries) are specialised nectar-secreting plant glands that develop outside of flowers and are not involved in pollination , generally on the leaf or petiole (foliar nectaries) and often in relation to the leaf venation . They are highly diverse in form, location, size, and mechanism. They have been described in virtually all above-ground plant parts—including stipules , cotyledons , fruits , and stems , among others. They range from single-celled trichomes to complex cup-like structures that may or may not be vascularized . Like floral nectaries, they consist of groups of glandular trichomes (e.g., Hibiscus spp.) or elongated secretory epidermal cells. The latter are often associated with underlying vascular tissue. They may be associated with specialised pockets ( domatia ), pits or raised regions (e.g., Euphorbiaceae ). The leaves of some tropical eudicots (e.g., Fabaceae ) and magnoliids (e.g., Piperaceae ) possess pearl glands or bodies which are globular trichomes specialised to attract ants. They secrete matter that
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#1732772997850902-859: The Cenozoic , with weak support for a role played by arthropod herbivore diversifications. They are absent in bryophytes , gymnosperms , early angiosperms , magnoliids , and members of Apiales among the eudicots. Phylogenetic studies and the wide distribution of extrafloral nectaries among vascular plants point to multiple independent evolutionary origins of extrafloral nectaries in at least 457 independent lineages. The main ingredients in nectar are sugars in varying proportions of sucrose , glucose , and fructose . In addition, nectars have diverse other phytochemicals serving to both attract pollinators and discourage predators. Carbohydrates , amino acids , and volatiles function to attract some species, whereas alkaloids and polyphenols appear to provide
943-646: The United States are controversial and criticised, as they may lead to new overwintering sites along the U.S. Gulf Coast and the consequent year-round breeding of monarchs. This is thought to adversely affect migration patterns, and to cause a dramatic build-up of the dangerous parasite, Ophryocystis elektroscirrha . New research also has shown that monarch larvae reared on tropical milkweed show reduced migratory development (reproductive diapause), and when migratory adults are exposed to tropical milkweed, it stimulates reproductive tissue growth. Because of this, it
984-584: The gynoecium from certain pathogens. Floral nectaries have evolved and diverged into the different types of nectaries due to the various pollinators that visit the flowers. In Melastomataceae , different types of floral nectaries have evolved and been lost many times. Flowers that ancestrally produced nectar and had nectaries may have lost their ability to produce nectar due to a lack of nectar consumption by pollinators, such as certain species of bees . Instead they focused on energy allocation to pollen production. Species of angiosperms that have nectaries use
1025-406: The coma (the "floss") are hollow and coated with wax, and have good insulation qualities. During World War II , more than 5,000 t (5,500 short tons) of milkweed floss was collected in the US as a substitute for kapok in life jackets. Milkweed is grown commercially as a hypoallergenic filling for pillows and as insulation for winter coats. Using milkweed floss for these purposes could provide
1066-493: The divergent evolution of the African honey bee, A. m. scutellata and the western honey bee . Nectar is an economically important substance as it is the sugar source for honey . It is also useful in agriculture and horticulture because the adult stages of some predatory insects feed on nectar. For example, a number of predacious or parasitoid wasps (e.g., the social wasp species Apoica flavissima ) rely on nectar as
1107-455: The dogbane family, Apocynaceae . The genus was formally described by Carl Linnaeus in 1753, who named it after Asclepius , the Greek god of healing. Members of the genus produce some of the most complex flowers in the plant kingdom, comparable to orchids in complexity. Five petals reflex backwards revealing a gynostegium surrounded by a five-membrane corona . The corona is composed of
1148-439: The flower, may determine the type of pollinator that visits the flower. Defense from herbivory is often one of the roles of extrafloral nectaries. Floral nectaries can also be involved in defense. In addition to the sugars found in nectar, certain proteins may also be found in nectar secreted by floral nectaries. In tobacco plants, these proteins have antimicrobial and antifungal properties and can be secreted to defend
1189-840: The forager after only a sip, motivating it to visit other plants, therefore maximizing the pollination efficiency gained by the plant for a minimum nectar output. Neurotoxins such as aesculin are present in some nectars such as that of the California buckeye . Nectar contains water, essential oils , carbohydrates , amino acids , ions , and numerous other compounds. Some insect pollinated plants lack nectaries, but attract pollinators through other secretory structures. Elaiophores are similar to nectaries but are oil secreting. Osmophores are modified structural structures that produce volatile scents. In orchids , these have pheromone qualities. Osmophores have thick domed or papillate epidermis and dense cytoplasm. Platanthera bifolia produces
1230-489: The insect may become trapped and die). Pollination is effected by the reverse procedure, in which one of the pollinia becomes trapped within the anther slit. Large-bodied hymenopterans (bees, wasps) are the most common and best pollinators, accounting for over 50% of all Asclepias pollination, whereas monarch butterflies are poor pollinators of milkweed. Asclepias species produce their seeds in pods termed follicles . The seeds, which are arranged in overlapping rows, bear
1271-897: The known occurrences. The families showing the most recorded occurrences of extrafloral nectaries are Fabaceae , with 1069 species, Passifloraceae , with 438 species, and Malvaceae , with 301 species. The genera with the most recorded occurrences are Passiflora (322 species, Passifloraceae), Inga (294 species, Fabaceae), and Acacia (204 species, Fabaceae). Other genera with extrafloral nectaries include Salix ( Salicaceae ), Prunus ( Rosaceae ) and Gossypium ( Malvaceae ). Foliar nectaries have also been observed in 101 species of ferns belonging to eleven genera and six families, most of them belonging to Cyatheales (tree ferns) and Polypodiales . Fern nectaries appear to have evolved around 135 million years ago, nearly simultaneously with angiosperms. However, fern nectaries did not diversify remarkably until nearly 100 million years later, in
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1312-543: The monarch butterfly, Danaus plexippus . The OE parasite causes holes to form in the wings of fully developed monarch butterflies. This causes weakened endurance and an inability to migrate. The parasite only infects monarchs when they are larvae and caterpillars, but the detriment is when they are in their butterfly form. By contrast, some species of Asclepias are extremely poor sources of cardenolides, such as Asclepias fascicularis , Asclepias tuberosa , and Asclepias angustifolia . The leaves of Asclepias species are
1353-406: The nectar from their flowers. A noteworthy feeder on milkweeds is the monarch butterfly , which uses and requires certain milkweeds as host plants for their larvae . The Asclepias genus contains over 200 species distributed broadly across Africa, North America, and South America. It previously belonged to the family Asclepiadaceae, which is now classified as the subfamily Asclepiadoideae of
1394-454: The nectar to attract pollinators that consume the nectar, such as birds and butterflies . In Bromeliaceae , septal nectaries (a form of gynoecial nectary) are common in species that are insect or bird pollinated. In species that are wind pollinated, nectaries are often absent because there is no pollinator. In flowers that are generally pollinated by a long-tongued organism such as certain flies , moths , butterflies, and birds, nectaries in
1435-428: The ovaries are common because they are able to reach the nectar reward when pollinating. Sepal and petal nectaries are often more common in species that are pollinated by short-tongued insects that cannot reach so far into the flower. Nectar secretion increases as the flower is visited by pollinators. After pollination, the nectar is frequently reabsorbed into the plant. The amount of nectar in flowers at any given time
1476-853: The plants have had many uses throughout human history. Milkweeds have a long history of medicinal, every day, and military use. The Omaha people from Nebraska , the Menomin from Wisconsin and upper Michigan , the Dakota from Minnesota , and the Ponca people from Nebraska , traditionally used common milkweed ( A. syriaca ) for medicinal purposes. The bast fibers of some species can be used for rope. The Miwok people of northern California used heart-leaf milkweed ( A. cordifolia ) for its stems, which they dried and used for cords, strings and ropes. The fine, silky fluff attached to milkweed seeds, which allows them to be distributed long distances on
1517-476: The pollinator that feeds on the plant's nectar. Nectar is secreted from epidermal cells of the nectaries, which have a dense cytoplasm , by means of trichomes or modified stomata . Adjacent vascular tissue conducts phloem bringing sugars to the secretory region, where it is secreted from the cells through vesicles packaged by the endoplasmic reticulum . The adjacent subepidermal cells may also be secretory. Flowers that have longer nectaries sometimes have
1558-461: The stigmatic slits and die. Milkweeds are also the larval food source for monarch butterflies and their relatives, as well as a variety of other herbivorous insects (including numerous beetles , moths , and true bugs ) specialized to feed on the plants despite their chemical defenses . Milkweeds use three primary defenses to limit damage caused by caterpillars : hairs on the leaves ( trichomes ), cardenolide toxins, and latex fluids. Data from
1599-436: The surface of the gynoecium. Nectaries may also vary in color, number, and symmetry. Nectaries can also be categorized as structural or non-structural. Structural nectaries refer to specific areas of tissue that exude nectar, such as the types of floral nectaries previously listed. Non-structural nectaries secrete nectar infrequently from non-differentiated tissues. The different types of floral nectaries coevolved depending on
1640-454: The wind, is known as floss. Milkweed floss is incredibly difficult to spin due to how short and smooth the filaments are, but blending it with as little as 25% wool or other fiber can produce workable yarn. A study of the insulative properties of various materials found that milkweed floss was outperformed by other materials in terms of insulation, loft, and lumpiness, but it scored well when mixed with down feathers. The milkweed filaments from
1681-614: The word "nectar" to refer to the "sweet liquid in flowers", is first recorded in AD 1600. A nectary or honey gland is floral tissue found in different locations in the flower and is one of several secretory floral structures, including elaiophores and osmophores, producing nectar, oil and scent respectively. The function of these structures is to attract potential pollinators , which may include insects, including bees and moths , and vertebrates such as hummingbirds and bats . Nectaries can occur on any floral part, but they may also represent