Asclepias asperula

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Antelope horns
Asclepias-asperula.jpg
Status TNC G5.svg
Secure  (NatureServe)
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Gentianales
Family: Apocynaceae
Genus: Asclepias
Species:
A. asperula
Binomial name
Asclepias asperula
Synonyms [1]
  • Acerates asperulaDecne.
  • Asclepias capricornuWoodson
  • Asclepias decumbens(Nutt.) K.Schum. nom. illeg.
  • Asclepiodora asperula(Decne.) E.Fourn.
  • Asclepiodora decumbens(Nutt.) A.Gray

Asclepias asperula, commonly called antelope horns milkweed or spider milkweed, [2] is a species of milkweed native to the Southwestern United States and northern Mexico.

Contents

Description

It is a perennial plant growing to 0.3–0.9 m (1–3 ft) tall, with clustered greenish-yellow flowers with maroon highlights. It blooms from April through June.

Antelope horns is a common milkweed in Central Texas. It gets its name from the follicles (seed pods) that resemble the horns of antelope. You can easily spot the flower clusters (technically, umbellate cymes) in open meadows. Milkweed plants are a major food source for Monarch and Queen butterfly caterpillars and as with other milkweed plants, it bleeds white latex if a stem is cut and this sap is toxic to some animals and to humans. It also makes Monarch and Queen butterflies taste bad to potential predators, a nice defense mechanism. From a distance the flowers appear as tennis-sized spheres, but they are clusters of small green, purple, and white flowers. Each flower has 5 pale green petals that cup upward around 5 prominent white hoods (which store nectar).

Antelope horns flower.png

Flower structure and pollination

Parts of an antelope horns flower Parts of a antelope horns flower.jpg
Parts of an antelope horns flower
Cross section of a single antelope horns flower Cross section of a single antelope horns flower.png
Cross section of a single antelope horns flower

The central circular structure is a gynostegium, the fusion of 2 stigma and 5 anthers. Antelope horns do not have individual pollen grains. The pollen sticks together as granular masses contained on a pollinarium structure located within each of the 5 stigmatic chambers. The pollinarium is made up of 2 pollinium “wings” connected to a central corpusculum via 2 translator arms. The picture "Antelope horns pollinarium" shows a pollinarium that was pulled out of the stigmatic slit using an insect pin.

Antelope horns pollinarium Antelope horns pollinarium.png
Antelope horns pollinarium
Parts of an Antelope horns pollinarium's Parts of an Antelope horns pollinarium's.png
Parts of an Antelope horns pollinarium's

Antelope Horns Pollination

Pollination of Antelope Horns happens when flowers are visited by insects that get their reward in nectar (in this case primarily sucrose) which is accessible at the base of each of the hoods. Several different types of insects visit milkweed searching for nectar including bees, butterflies, moths, flies and beetles. As they move around the flower in search of nectar one of their legs may slip into a stigmatic slit. The only way to safely remove their leg is to move it upwards toward the top of the slit. The leg can then snag on the corpusculum and pull out the entire pollinarium. When the insect visits another milkweed flower carrying this pollinarium, there is a chance a pollinium would slip into an empty stigmatic slit, dislodge, and remain there. If the orientation of the pollinium is correct and the concentration of nectar surrounding a pollinium is optimal, pollination will take place.

Pollen tubes grow out of a germination pore on the convex surface of the pollen mass on pollinium into the stigma and down one of the 2 styles to the ovary where the male genetic material fertilizes the (female) ovules. Each ovule has the potential to form one seed. The image "Antelope Horns pollen tube" shows the route pollen tubes take to transfer genetic material into an ovary. Asclepias asperula does not self-pollinate so they are dependent on attracting pollinators that will transfer pollen between plants.

Antelope Horns pollen tube Antelope Horns pollen tube.png
Antelope Horns pollen tube

Taxonomy

Asclepias asperula is divided into two subspecies: A. asperula. ssp. asperula and A. asperula ssp. capricornu. Ssp. capricornu occurs in comparatively more mesic conditions and has comparatively broader leaves, floral crowns that are more white, and a more prostrate habit. Ssp. asperula occurs in comparatively more arid conditions and has comparatively narrower leaves, floral crowns that are more purple, and a more upright habit. [3] [2]

Ecology

Like several other species of milkweed, A. asperula is a food for monarch butterfly caterpillars. Along with being food for monarchs, the plants also contain toxic cardiac glycosides (cardenolides) that the monarchs retain, making them unpalatable and poisonous to predators. For the same reason, A. asperula can be poisonous to livestock and other animals, including humans.

In addition to the monarch, it is a larval host to the dogbane tiger moth, the queen butterfly, and the unexpected cycnia. [4]

Cultivation

The plant is difficult to cultivate and does not grow well in containers. [5] [6] In cultivation, this species favors quickly draining soil that is high in inorganic matter, such as sand and rock chips. It can grow in loam and clay, if provided with adequate drainage and frequent dryness. [7] Moisture level demands and tolerance depend upon the subspecies and possibly ecotype. The plant has a deep taproot, so it needs to have the deepest-possible pot if grown in a container and should not be waterlogged. [7]

Related Research Articles

<span class="mw-page-title-main">Pollinator</span> Animal that moves pollen from the male anther of a flower to the female stigma

A pollinator is an animal that moves pollen from the male anther of a flower to the female stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains.

<i>Asclepias tuberosa</i> Species of flowering plant

Asclepias tuberosa, commonly known as butterfly weed, is a species of milkweed native to eastern and southwestern North America. It is commonly known as butterfly weed because of the butterflies that are attracted to the plant by its color and its copious production of nectar.

<span class="mw-page-title-main">Monarch butterfly</span> Milkweed butterfly in the family Nymphalidae

The monarch butterfly or simply monarch is a milkweed butterfly in the family Nymphalidae. Other common names, depending on region, include milkweed, common tiger, wanderer, and black-veined brown. It is amongst the most familiar of North American butterflies and an iconic pollinator, although it is not an especially effective pollinator of milkweeds. Its wings feature an easily recognizable black, orange, and white pattern, with a wingspan of 8.9–10.2 cm (3.5–4.0 in). A Müllerian mimic, the viceroy butterfly, is similar in color and pattern, but is markedly smaller and has an extra black stripe across each hindwing.

<span class="mw-page-title-main">Pollinium</span>

A pollinium is a coherent mass of pollen grains in a plant that are the product of only one anther, but are transferred, during pollination, as a single unit. This is regularly seen in plants such as orchids and many species of milkweeds (Asclepiadoideae). Usage of the term differs: in some orchids two masses of pollen are well attached to one another, but in other orchids there are two halves each of which is sometimes referred to as a pollinium.

<i>Asclepias</i> Genus of flowering plants

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 them or from them. The most notable of them is the monarch butterfly, which uses and requires certain milkweeds as host plants for their larvae.

<i>Asclepias syriaca</i> Species of flowering plant

Asclepias syriaca, commonly called common milkweed, butterfly flower, silkweed, silky swallow-wort, and Virginia silkweed, is a species of flowering plant. It is native to southern Canada and much of the United States east of the Rocky Mountains, excluding the drier parts of the prairies. It is in the genus Asclepias, the milkweeds. It grows in sandy soils as well as other kinds of soils in sunny areas.

<i>Asclepias incarnata</i> Species of flowering plant

Asclepias incarnata, the swamp milkweed, rose milkweed, rose milkflower, swamp silkweed, or white Indian hemp, is a herbaceous perennial plant species native to North America. It grows in damp through wet soils and also is cultivated as a garden plant for its flowers, which attract butterflies and other pollinators with nectar. Like most other milkweeds, it has latex containing toxic chemicals, a characteristic that repels insects and other herbivorous animals.

<span class="mw-page-title-main">Butterfly gardening</span> Gardening to benefit butterflies

Butterfly gardening is a way to create, improve, and maintain habitat for lepidopterans including butterflies, skippers, and moths. Butterflies have four distinct life stages—egg, larva, chrysalis, and adult. In order to support and sustain butterfly populations, an ideal butterfly garden contains habitat for each life stage.

<i>Asclepias curassavica</i> Species of flowering plant

Asclepias curassavica, commonly known as tropical milkweed, is a flowering plant species of the milkweed genus, Asclepias. It is native to the American tropics and has a pantropical distribution as an introduced species. Other common names include bloodflower or blood flower, cotton bush, hierba de la cucaracha, Mexican butterfly weed, redhead, scarlet milkweed, and wild ipecacuanha.

<i>Asclepias purpurascens</i> Species of flowering plant

Asclepias purpurascens, the purple milkweed, is a herbaceous plant species. It is in the genus Asclepias, making it a type of milkweed. It is native to the Eastern, Southern and Midwestern United States similar to the range of the common milkweed. The plant gets its name from the flowers that first develop a pink color but then turn darker purple as they mature. Unlike common milkweed, purple milkweed prefers some shade and is considered a plant of partial shade. It is also considered an indicator of oak savanna, especially in Wisconsin. The species rarely produces seed pods which are smooth, instead of the rough warty ones produced by common milkweed.

<i>Asclepias verticillata</i> Species of flowering plant

Asclepias verticillata, the whorled milkweed, eastern whorled milkweed, or horsetail milkweed, is a species of milkweed native to most of eastern North America and parts of western Canada and the United States.

<i>Phlox divaricata</i> Species of flowering plant

Phlox divaricata, the wild blue phlox, woodland phlox, or wild sweet william, is a species of flowering plant in the family Polemoniaceae, native to forests and fields in eastern North America.

<i>Asclepias speciosa</i> Species of flowering plant

Asclepias speciosa is a milky-sapped perennial plant in the dogbane family (Apocynaceae), known commonly as the showy milkweed and is found in the western half of North America.

<i>Asclepias meadii</i> Species of flowering plant

Asclepias meadii is a rare species of milkweed known by the common name Mead's milkweed. It is native to the American Midwest, where it was probably once quite widespread in the tallgrass prairie. Today much of the Midwest has been fragmented and claimed for agriculture, and the remaining prairie habitat is degraded.

<i>Asclepias quadrifolia</i> Species of flowering plant

Asclepias quadrifolia, commonly called four-leaved milkweed or fourleaf milkweed, is a species of milkweed in the Apocynaceae (dogbane) family. It is sometimes referred to as whorled milkweed, but it should not be confused with Asclepias verticillata. A. quadrifolia occurs in the eastern United States and Canada.

<i>Asclepias lanceolata</i> Species of plant

Asclepias lanceolata, the fewflower milkweed, is a species of milkweed that is native to the coastal plain of the United States from New Jersey to Florida and Southeast Texas. A. lanceolata is an upright, perennial plant that can grow between 3 and 5 feet tall, with red-orange flowers blooming in the summer months. It can also be referred to as Cedar Hill milkweed, as it was first described by Dr. Eli Ives in the neighborhood of Cedar Hill in New Haven, Connecticut.

<i>Asclepias sullivantii</i> Species of plant

Asclepias sullivantii is a species of flowering plant in the milkweed genus, Asclepias. Common names include prairie milkweed, Sullivant's milkweed, and smooth milkweed. It is native to North America, where it occurs in the central United States and Ontario in Canada.

<i>Asclepias curtissii</i> Species of plant

Asclepias curtissii, or Curtiss's milkweed, is a rare species of flowering milkweed that is endemic to Florida's sandy areas. Curtiss's milkweed belongs to the subfamily Asclepiadoideae and the genus Asclepias. This dicotyledonous, perennial plant was placed on the endangered species list by the state of Florida to protect this rare milkweed. Although Curtiss milkweed is found all over Florida, the populations are very isolated and concentrated.

<i>Asclepias angustifolia</i> Species of plant

Asclepias angustifolia, commonly called the Arizona milkweed, is an endemic species of milkweed native only to Arizona.

<span class="mw-page-title-main">Pollination of orchids</span>

The pollination of orchids is a complex chapter in the biology of this family of plants that are distinguished by the complexity of their flowers and by intricate ecological interactions with their pollinator agents. It has captured the attention of numerous scientists over time, including Charles Darwin, father of the theory of evolution by natural selection. Darwin published in 1862 the first observations of the fundamental role of insects in orchid pollination, in his book The Fertilization of Orchids. Darwin stated that the varied stratagems orchids use to attract their pollinators transcend the imagination of any human being.

References

  1. "The Plant List: A Working List of All Plant Species" . Retrieved 12 April 2015.
  2. 1 2 "Asclepias asperula ssp. capricornu". Lady Bird Johnson Wildflower Center. The University of Texas at Austin. 2019. Retrieved 21 January 2019.
  3. "Asclepias asperula subsp. asperula". The Jepson Herbarium. Regents of the University of California. 2019. Retrieved 21 January 2019.
  4. The Xerces Society (2016). Gardening for Butterflies: How You Can Attract and Protect Beautiful, Beneficial Insects. Timber Press. ISBN   978-1-60469-761-2.[ page needed ]
  5. "Persnickety Texas Milkweeds "May not Lend Themselves to Mass Seed Production"". 13 March 2013.
  6. "How to Get Texas Native Milkweed Seeds to Germinate". 13 March 2013.
  7. 1 2 "Asclepias asperula — Antelope Horn". Plant Finder. Native American Seed. 2019. Retrieved 21 January 2019.

Further reading