Триггер өсімдіктері: Stylidium туысы

Genus of plants

Stylidium (the triggerplants or trigger plants) is a genus of dicotyledonous plants that belong to the family Stylidiaceae. The genus name Stylidium is derived from the Greek στύλος or stylos (column or pillar), which refers to the distinctive reproductive structure that its flowers possess. Pollination is achieved through the use of the sensitive "trigger", which comprises the male and female reproductive organs fused into a floral column that snaps forward quickly in response to touch, harmlessly covering the insect in pollen. Most of the approximately 300 species are only found in Australia, making it the fifth largest genus in that country. Triggerplants are considered to be protocarnivorous or carnivorous because the glandular trichomes that cover the scape and flower can trap, kill, and digest small insects with protease enzymes produced by the plant. Recent research has raised questions as to the status of protocarnivory within Stylidium. Members of the genus are most easily identified by their unique floral column, in which the stamen and style are fused. The column—also commonly called a "trigger" in this genus—typically resides beneath the plane of the flower. Stylidium flowers are zygomorphic, which means they are only symmetrical in one plane. Flowers usually bloom in the late spring in Australia.

Species of the genus Stylidium represent a very diverse selection of plants. Some are only a few centimeters tall, while others can grow to be tall (S. laricifolium). One typical plant form is a dense rosette of leaves close to the ground that gives rise to the floral spike in the center. Plant forms range from wiry, creeping mats (S. scandens) to the bushy S. laricifolium. Flower morphology differs in details, but ascribes to a simple blueprint: four petals, zygomorphic in nature, with the trigger protruding from the "throat" of the flower and resting below the plane of the flower petals. Flower size ranges from many species that have small wide flowers to the wide flowers of S. schoenoides. Flower color can also vary from species to species, but most include some combination of white, cream, yellow, or pink. Flowers are usually arranged in a spike or dense raceme, but there is at least one exception to the rule: S. uniflorum, as its name suggests, produces a single flower per inflorescence. Upon impact, the insect will be covered in pollen and stunned, but not harmed. Because the column comprises the fused male and female reproductive organs of the flower, the stamen and stigma take turns in dominating the function of the column—the anthers develop first and then are pushed aside by the developing stigma. This delayed development of the stigma prevents self pollination and ensures that cross pollination will occur between individuals of a population. Different species have evolved the trigger mechanism in different locations, with some attacking the pollinating insect from above and others from below (a "punch in the gut" to the insect). The response to touch is very quick in Stylidium species. The column can complete its "attack" on the insect in as little as 15 milliseconds. After firing, the column resets to its original position in anywhere from a few minutes to a half hour, depending on temperature and species specific qualities. The column is able to fire many times before it no longer responds to stimuli. The response time is highly dependent upon ambient temperature, with lower temperatures relating to slower movement. Stylidium species are typically pollinated by small solitary bees and the nectar feeding bee flies (Bombyliidae).

Stylidium species with glandular trichomes on their sepals, leaves, flower parts, or scapes have been suggested to be protocarnivorous (or paracarnivorous). The tip of the trichome produces a sticky mucilage—a mixture of sugar polymers and water—that is capable of attracting and suffocating small insects. The insects captured by the glandular trichomes are too small to serve any role in pollination. It is unclear, however, whether these plants evolved the ability to trap and kill insects as an adaptation to low environmental nutrient availability or simply a defensive mechanism against insects damaging flower parts.

Most Stylidium species are endemic to Australia. In Western Australia alone, there are more than 150 species, at least 50 of which are in the area immediately around Perth. There are at least four species of Stylidium that are not confined to the Australian continent: S. tenellum is found in Myanmar, Melaka, and Tonkin; S. kunthii in Bengal and Myanmar; S. uliginosum in Queensland, Sri Lanka, and the south coast of China; and S. alsinoides in Queensland and the Philippines. The cladistic group Stylidium contains more than 230 individual species (more than 300 species exist, but many specimens have not yet been formally described), making it the fifth largest genus in Australia.

Discovery and description of new Stylidium species has been occurring since the late 18th century, the first of which was discovered in Botany Bay in 1770 by Joseph Banks and Daniel Solander during their travels in the Pacific with James Cook aboard the Endeavour. As of 2002, only 221 Stylidium species were known. There are now over 300 species, many of which are awaiting formal description.

Most Stylidium species tend to be hardy species and can be easily cultivated in greenhouses or gardens. They are drought resistant, hardy to cold weather, and the species diversity in this genus gives gardeners a wide variety of choices. Most species that are native to Western Australia will be cold hardy to at least 1 to 2 °C. The few that can be found all over Australia, like S. graminifolium, will tolerate a wider range of habitat since their native ranges includes a great diversity of ecoregions. Some species of triggerplants are suitable for cultivation outdoors outside of the Australian continent including most of the United Kingdom and as far north as New York City or Seattle in the United States. Cultivation from seed may be difficult or easy, depending on the species. The more difficult species to grow include the ones that require a period of dormancy or smoke treatment to simulate a bushfire. Stylidium specimens should be grown in a medium that is kept moist and has a relatively low concentration of nutrients. They appear to be sensitive to disturbance of their root systems. Minimization of such disturbance will likely result in healthier plants.