A shrub or bush is a small-to-medium-sized perennial woody plant . Unlike herbaceous plants , shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple stems and shorter height , less than 6–10 m (20–33 ft) tall. Small shrubs, less than 2 m (6.6 ft) tall are sometimes termed as subshrubs . Many botanical groups have species that are shrubs, and others that are trees and herbaceous plants instead.
40-596: Some define a shrub as less than 6 m (20 ft) and a tree as over 6 m. Others use 10 m (33 ft) as the cutoff point for classification. Many trees do not reach this mature height because of hostile, less than ideal growing conditions, and resemble shrub-sized plants. Others in such species have the potential to grow taller in ideal conditions. For longevity, most shrubs are classified between perennials and trees. Some only last about five years in good conditions. Others, usually larger and more woody, live beyond 70. On average, they die after eight years. Shrubland
80-443: A century plant can live for 80 years and grow 30 meters tall before flowering and dying. However, most perennials are polycarpic (or iteroparous ), flowering over many seasons in their lifetime. Perennials invest more resources than annuals into roots, crowns, and other structures that allow them to live from one year to the next. They often have a competitive advantage because they can commence their growth and leaf out earlier in
120-940: A photolyase and the other, a protein involved in nucleotide excision repair ). Perennials that are cultivated include: woody plants like fruit trees grown for their edible fruits; shrubs and trees grown as landscaping ornamentals ; herbaceous food crops like asparagus , rhubarb , strawberries ; and subtropical plants not hardy in colder areas such as tomatoes , eggplant , and coleus (which are treated as annuals in colder areas). Perennials also include plants grown for their flowering and other ornamental value including bulbs (like tulips, narcissus, and gladiolus); lawn grass, and other groundcovers , (such as periwinkle and Dichondra ). Each type of plant must be separated differently; for example, plants with fibrous root systems like daylilies, Siberian iris, or grasses can be pried apart with two garden forks inserted back to back, or cut by knives. However, plants such as bearded irises have
160-464: A " stool ", removes everything but vital parts of the plant, resulting in long new stems known as "canes". Other shrubs respond better to selective pruning to dead or unhealthy, or otherwise unattractive parts to reveal their structure and character. Shrubs in common garden practice are generally considered broad-leaved plants , though some smaller conifers such as mountain pine and common juniper are also shrubby in structure. Species that grow into
200-549: A few feet. Dominant and co-dominant canopy trees form the uneven canopy layer. Canopy trees are able to photosynthesize relatively rapidly with abundant light, so it supports the majority of primary productivity in forests. The canopy layer provides protection from strong winds and storms while also intercepting sunlight and precipitation, leading to a relatively sparsely vegetated understory layer. Forest canopies are home to unique flora and fauna not found in other layers of forests. The highest terrestrial biodiversity resides in
240-460: A plant canopy. Leaf area index , leaf area per unit ground area, is a key measure used to understand and compare plant canopies. The canopy is taller than the understory layer. The canopy holds 90% of the animals in the rainforest. Canopies can cover vast distances and appear to be unbroken when observed from an airplane. However, despite overlapping tree branches, rainforest canopy trees rarely touch each other. Rather, they are usually separated by
280-453: A reasonable length beforehand. Many trees can grow in multiple stemmed forms also while being tall enough to be trees, such as oak or ash . An area of cultivated shrubs in a park or a garden is known as a shrubbery . When clipped as topiary , suitable species or varieties of shrubs develop dense foliage and many small leafy branches growing close together. Many shrubs respond well to renewal pruning , in which hard cutting back to
320-454: A role in modifying the internal environment of the forest by acting as a buffer for incoming light, wind, and temperature fluctuations. The forest canopy layer supports a diverse range of flora and fauna. It has been dubbed "the last biotic frontier" as it provides a habitat that has allowed for the evolution of countless species of plants, microorganisms, invertebrates (e.g., insects), and vertebrates (e.g., birds and mammals) that are unique to
360-470: A root system of rhizomes; these root systems should be planted with the top of the rhizome just above ground level, with leaves from the following year showing. The point of dividing perennials is to increase the amount of a single breed of plant in your garden. In the United States more than 900 million dollars worth of potted herbaceous perennial plants were sold in 2019. Although most of humanity
400-516: A shrubby habit may be either deciduous or evergreen . In botany and ecology , a shrub is more specifically used to describe the particular physical canopy structure or plant life-form of woody plants which are less than 8 metres (26 ft) high and usually multiple stems arising at or near the surface of the ground. For example, a descriptive system widely adopted in Australia is based on structural characteristics based on life-form, plus
440-921: A small number of shrubs have culinary usage. Apart from the several berry -bearing species (using the culinary rather than botanical definition), few are eaten directly, and they are generally too small for much timber use unlike trees. Those that are used include several perfumed species such as lavender and rose , and a wide range of plants with medicinal uses. Tea and coffee are on the tree-shrub boundary; they are normally harvested from shrub-sized plants, but these would be large enough to become small trees if left to grow instead. Shrubs are perennial woody plants, and therefore have persistent woody stems above ground (compare with succulent stems of herbaceous plants ). Usually, shrubs are distinguished from trees by their height and multiple stems. Some shrubs are deciduous (e.g. hawthorn ) and others evergreen (e.g. holly ). Ancient Greek philosopher Theophrastus divided
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#1732783616456480-479: A very few (e.g. Zostera ) occurring in shallow sea water. Herbaceous perennial plants are particularly dominant in conditions too fire-prone for trees and shrubs, e.g., most plants on prairies and steppes are perennials; they are also dominant on tundra too cold for tree growth. Nearly all forest plants are perennials, including trees and shrubs. Perennial plants are usually better long-term competitors, especially under stable, resource-poor conditions. This
520-783: Is due to the development of larger root systems which can access water and soil nutrients deeper in the soil and to earlier emergence in the spring. Annual plants have an advantage in disturbed environments because of their faster growth and reproduction rates. Each section contains a short list of species related to that topic, these are an example as the true lists would fill several books. Perennials grown for their decorative flowers include very many species and types. Some examples include: The majority of fruit bearing plants are perennial even in temperate climates. Examples include: Many herbs are perennial, including these examples: Many vegetable plants can grow as perennials in tropical climates, but die in cold weather. Examples of some of
560-483: Is fed by the re-sowing of the seeds of annual grain crops, (either naturally or by the manual efforts of humans), perennial crops provide numerous benefits. Perennial plants often have deep, extensive root systems which can hold soil to prevent erosion , capture dissolved nitrogen before it can contaminate ground and surface water, and out-compete weeds (reducing the need for herbicides ). These potential benefits of perennials have resulted in new attempts to increase
600-519: Is the natural landscape dominated by various shrubs; there are many distinct types around the world, including fynbos , maquis , shrub-steppe , shrub swamp and moorland . In gardens and parks, an area largely dedicated to shrubs (now somewhat less fashionable than a century ago) is called a shrubbery , shrub border or shrub garden. There are many garden cultivars of shrubs, bred for flowering, for example rhododendrons , and sometimes even leaf colour or shape. Compared to trees and herbaceous plants,
640-429: Is too cold or dry. In many parts of the world, seasonality is expressed as wet and dry periods rather than warm and cold periods, and deciduous perennials lose their leaves in the dry season. Some perennial plants are protected from wildfires because they have underground roots that produce adventitious shoots, bulbs, crowns , or stems ; other perennials like trees and shrubs may have thick cork layers that protect
680-475: The astronomical symbol for the planet Jupiter . Perennial plants can be short-lived (only a few years) or long-lived. They include a wide assortment of plant groups from non-flowering plants like ferns and liverworts to highly diverse flowering plants like orchids , grasses , and woody plants . Plants that flower and fruit only once and then die are termed monocarpic or semelparous ; these species may live for many years before they flower. For example,
720-455: The understory . In some cases, they would use unconventional methods such as chairs suspended on vines or hot-air dirigibles, among others. Modern technology, including adapted mountaineering gear, has made canopy observation significantly easier and more accurate, allowed for longer and more collaborative work, and broadened the scope of canopy study. Canopy structure is the organization or spatial arrangement (three-dimensional geometry) of
760-446: The advantage of generating larger seedlings that can better compete with other plants. Perennials also produce seeds over many years. An important aspect of cold acclimation is overexpression of DNA repair genes. In Thinopyrum intermedium a perennial relative of common wheat Triticum aestivum , conditions of freezing stress were shown to be associated with large increases in expression of two DNA repair genes (one gene product
800-479: The canopies of tropical rainforests . Many rainforest animals have evolved to live solely in the canopy and never touch the ground. The canopy of a rainforest is typically about 10 m thick, and intercepts around 95% of sunlight. The canopy is below the emergent layer , a sparse layer of very tall trees, typically one or two per hectare. With an abundance of water and a near ideal temperature in rainforests, light and nutrients are two factors that limit tree growth from
840-409: The canopy and subtract throughfall and stem flow ). However, the problem with this method is that the canopy is not homogeneous, which causes difficulty in obtaining representative throughfall data. A method employed to avoid this problem is covering forest floor with plastic sheets and collecting the throughfall. The disadvantage of this method is that it is not suitable for long periods, because in
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#1732783616456880-410: The canopy layer are thought to be involved in maintaining forest diversity, resilience , and functioning. Shade trees normally have a dense canopy that blocks light from lower growing plants. Early observations of canopies were made from the ground using binoculars or by examining fallen material. Researchers would sometimes erroneously rely on extrapolation by using more reachable samples taken from
920-408: The category of perennials, underscoring the prevalence of plants with lifespans exceeding two years in the botanical world. Perennials (especially small flowering plants ) that grow and bloom over the spring and summer, die back every autumn and winter, and then return in the spring from their rootstock or other overwintering structure, are known as herbaceous perennials . However, depending on
960-510: The dormancy period is over and new growth begins. In climates that are warm all year long, perennials may grow continuously. Annuals which complete their life cycle in one growing season, in contrast with perennials, produce seeds as the next generation and die; the seeds may survive cold or dry periods or germinate soon after dispersal depending on the climate. Some perennials retain their foliage year-round; these are evergreen perennials. Deciduous perennials shed all their leaves part of
1000-482: The effects of precipitation on the local climate. Forest canopies also buffer the effects of temperature within forests by creating vertical light gradients. Variations in forest microclimate are also driven by the structure and physiology of canopy trees and epiphytes. This produces feedback loops where the species identity, growth traits, and forest stand composition of canopy trees determine forest microclimate. Forest canopies are significantly involved in maintaining
1040-412: The greenhouse effect, thereby causing the planet to become warmer. Canopy interception is the rainfall that is intercepted by the canopy of a tree and successively evaporates from the leaves. Precipitation that is not intercepted will fall as throughfall or stemflow on the forest floor. Many methods exist to measure canopy interception. The most often used method is by measuring rainfall above
1080-541: The growing season, and can grow taller than annuals. In doing so they can better compete for space and collect more light. Perennials typically grow structures that allow them to adapt to living from one year to the next through a form of vegetative reproduction rather than seeding. These structures include bulbs , tubers , woody crowns, rhizomes , turions , woody stems, or crowns which allows them to survive periods of dormancy over cold or dry seasons; these structures typically store carbohydrates which are used once
1120-415: The height and amount of foliage cover of the tallest layer or dominant species . For shrubs that are 2–8 metres (6.6–26.2 ft) high, the following structural forms are categorized: For shrubs less than 2 metres (6.6 ft) high, the following structural forms are categorized: Those marked with * can also develop into tree form if in ideal conditions. Perennial plant In horticulture ,
1160-620: The hormones produced due to environmental situations (i.e., seasons), reproduction, and stage of development to begin and halt the ability to grow or flower. There is also a distinction between the ability to grow and the actual task of growth. For example, most trees regain the ability to grow during winter but do not initiate physical growth until the spring and summer months. The start of dormancy can be seen in perennial plants through withering flowers, loss of leaves on trees, and halting of reproduction in both flowering and budding plants. Perennial species may produce relatively large seeds that have
1200-542: The more completely perennial vegetables are: Many aquatic plants are perennial even though many do not have woody tissue. Examples include: Canopy (biology) In biology , the canopy is the aboveground portion of a plant cropping or crop , formed by the collection of individual plant crowns . In forest ecology , the canopy is the upper layer or habitat zone, formed by mature tree crowns and including other biological organisms ( epiphytes , lianas , arboreal animals , etc..). The communities that inhabit
1240-539: The plant world into trees, shrubs and herbs. Small, low shrubs, generally less than 2 m (6.6 ft) tall, such as lavender , periwinkle and most small garden varieties of rose , are often termed as subshrubs . Most definitions characterize shrubs as possessing multiple stems with no main trunk below. This is because the stems have branched below ground level. There are exceptions to this, with some shrubs having main trunks, but these tend to be very short and divide into multiple stems close to ground level without
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1280-461: The rigours of the local climate (temperature, moisture, organic content in the soil, microorganisms), a plant that is a perennial in its native habitat, may be treated by a gardener as an annual and planted out every year, from seed, from cuttings, or from divisions. Tomato vines, for example, live several years in their natural tropical/ subtropical habitat but are grown as annuals in temperate regions because their above-ground biomass does not survive
1320-465: The seed yield of perennial species, which could result in the creation of new perennial grain crops. Some examples of new perennial crops being developed are perennial rice and intermediate wheatgrass . A perennial rice developed in 2018, was reported in 2023, to have provided a similar yield to replanted annual rice when evaluated over eight consecutive harvests. Perennial plants dominate many natural ecosystems on land and in fresh water, with only
1360-446: The stability of the global climate. They are responsible for at least half of the global carbon dioxide exchange between terrestrial ecosystems and the atmosphere. Forest canopies act as carbon sinks, reducing the increase of atmospheric CO 2 caused by human activity. The destruction of forest canopies would lead to the release of carbon dioxide, resulting in an increased concentration of atmospheric CO 2 . This would then contribute to
1400-431: The stems. Herbaceous perennials from temperate and alpine regions of the world can tolerate the cold during winter. Perennial plants may remain dormant for long periods and then recommence growth and reproduction when the environment is more suitable, while most annual plants complete their life cycle during one growing period, and biennials have two growing periods. The meristem of perennial plants communicates with
1440-446: The term ( per- + -ennial , "through the year") is used to differentiate a plant from shorter-lived annuals and biennials . It has thus been defined as a plant that lives more than two years. The term is also loosely used to distinguish plants with little or no woody growth (secondary growth in girth) from trees and shrubs, which are also technically perennials . Notably, it is estimated that 94% of plant species fall under
1480-443: The understory to the canopy. In the permaculture and forest gardening community, the canopy is the highest of seven layers. Forest canopies have unique structural and ecological complexities and are important for the forest ecosystem. They are involved in critical functions such as rainfall interception, light absorption, nutrient and energy cycling, gas exchange, and providing habitat for diverse wildlife. The canopy also plays
1520-492: The upper layer of forests. Forest canopies are arguably considered some of the most species-rich environments on the planet. It is believed that the communities found within the canopy layer play an essential role in the functioning of the forest, as well as maintaining diversity and ecological resilience . Forest canopies contribute to forest microclimate by controlling and buffering variations in climatic conditions. Forest canopies intercept rain and snowfall, thereby buffering
1560-405: The winter. There is also a class of evergreen perennials which lack woody stems, such as Bergenia which retain a mantle of leaves throughout the year. An intermediate class of plants is known as subshrubs , which retain a vestigial woody structure in winter, e.g. Penstemon . The symbol for a perennial plant, based on Species Plantarum by Linnaeus , is [REDACTED] , which is also
1600-439: The year. Deciduous perennials include herbaceous and woody plants; herbaceous plants have stems that lack hard, fibrous growth, while woody plants have stems with buds that survive above ground during dormancy. Some perennials are semi-deciduous, meaning they lose some of their leaves in either winter or summer. Deciduous perennials shed their leaves when growing conditions are no longer suitable for photosynthesis, such as when it
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