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Stolons

Stolons are modified stems whose purpose is to spread the plant over the surface of the ground. Stolons in strawberries will run out from a given strawberry plant, form a single node in the middle and then at the second node it will form a new plant will form.

How do the shoots spread? How are they linked?

Stolon
Tiller; runner; shoot that bends down to the ground and takes root, or a horizontal stem (on or below the ground) that gives rise to a new plant at its tip (e.g. Strawberries)

A stolon is a specialized type of horizontal above-ground shoot, a colonizing organ that arises from an axillary bud near the base of the plant. The stolon differs from the typical vegetative shoot of that same plant in having much longer and, typically, thinner internodes, and the horizontal stolon also has a strong tendency to form adventitious roots at the nodes. A mother plant produces stolons often in several compass directions, permitting cloning, i.e., vegetative reproduction, by producing young ramets (plantlets) around the plant. The stolon, connecting mother plant with each ramet, initially provides the pathway for a flow of nutrients and water to the new plantlet, or even some nutrients from the plantlet back to the mother plant, but that physical connection is eventually severed or becomes dysfunctional as the plantlet develops its nutritional independence. After the stolons are severed, a mother plant is encircled by satellite plantlets, which soon grow larger, filling in any space between the plants. In this way, stoloniferous species usually colonize open ground by forming a continuous ground cover, and thereby can exclude other species by crowding them out. Understandably, therefore, many species that have been domesticated as turfgrasses and ground covers are stoloniferous, forming dense clonal monocultures.

The most common textbook example of a stolon is the strawberry (Fragaria), in which the mother plant forms plantlets on stolons during spring growth. In the case of strawberry, the stolon is often termed a runner. Some authors treat a runner as a specialized form of the stolon, in which the leaves on the stolon are reduced to very small or minute scales, in contrast to the stolon, on which some leaf blade can be observed, so that the stolon is actually a photosynthetic unit. By itself, a runner is not a self-sustaining structure, merely a connector between ramet and mother plant. In both cases, the leaves of the typical vegetative shoot are different from the stoloniferous shoots, i.e., the plant is heteroblastic. Many plants that have above-ground stolons also form horizontal, below-ground rhizomes. Good examples of this can be found among grasses, such as bermudagrass (Cynodon dactylon). Numerous plants grow by forming stems next to the substrate. If the plant is lying on the substrate but does not form adventitious roots, the growth habit is termed procumbent. If the plant is lying on the substrate and forms adventitious roots, the growth habit is termed either repent or stoloniferous. Using the term stoloniferous generally requires that the plant must have two different types of vegetative shoots, not only one type, the creeping shoot.

Examples of Stoloniferous Plants

Stoloniferous plants are generally found in habitats where water is abundant or soil is very wet during the season when stolons are formed. For example, one notable California wetland species that spreads via stolons is yerba mansa, Anemopsis californica (Family Saururaceae). Widespread stoloniferous herbs of wet habitats are the buttercup Ranunculus flammula (Family Ranunculaceae) and mudwort, Limosella subulata (Family Scrophulariaceae).

  1. Among aquatic plants are the highly successful floating aquatic water hyacinth, Eichhornia crassipes (Family Pontederiaceae), in which thick, white stolons enable this species to clone at an alarming high rate. Other wideranging and highly competitive stoloniferous floating aquatics are water soldier (Stratiotes aloides) (Hydrocharitaceae), water lettuce (Pistia stratiotes, Family Araceae), Hydrocharis morsus-ranae (Hydrocharitaceae), and Potentilla palustris (Family Rosaceae). Wetlands also may include marsh claytonia (Claytonia palustris, Family Portulacaceae), tinker's penny (Hypericum anagalloides, Family Hypericaceae), and the fireweed Epilobium palustre (Family Onagraceae). Myosotis scorpioides is a stolon-like plant of shallow water. In tidal coastal salt marsh, the fleshy Jaumea carnosa and the saltgrass Distichlis spicata both may spread via stolons.
  2. In addition to species of strawberry (Fragaria), other stoloniferous herbs of the rose family (Rosaceae) can be found. Species that appear in the flora of California are Indian strawberry (Duchesnea indica) and Geum reptans. Rosaceous stoloniferous herbs are successful in a variety of habitats, including sand dunes and wet mountain meadows. Acaena can be a colonizer of new habitats via stolons.
  3. Woodland and high elevation habitats may have stoloniferous species of pussytoes, Antennaria (Family Asteraceae). In the southern Southern Hemisphere, e.g., in Patagonia, can be found the small-leaved stoloniferous species of Gunnera, e.g., G. magellanica.
  4. Saxifraga stolonifera (Family Saxifragaceae) is an interesting shade-loving woodland perennial that forms thin red stolons during spring growth.
  5. The cultivated white or Irish potato (Solanum tuberosum, Family Solanaceae) forms its edible tuber at the tip of a stolon. The stolons grows from an axillary bud at the base of the shoot, and its tip, forming a tuber, becomes buried in the leaf litter and loose soil around the plant, where the tuber develops.
  6. Hens and chickens, Sempervivum (Family Crassulaceae), form dense mats of leaf succulent rosettes via stolons.
  7. Grass species commonly used as turfgrass are stoloniferous, and they also spread via aggressive creeping rhizomes.
    • Bermudagrass, Cynodon dactylon
    • St. Augustine grass, Stenotaphrum secundatum
    • Some species of bluegrass, including the widely planted Kentucky bluegrass, an annual (Poa annuaP. macrantha, P. douglasii, and P. confinus. Poa palustris is a stoloniferous species growing along California streams and in wet meadows.
    • Agrostis stolonifera, creeping bent grass, is, true to its name, stoloniferous.
    • Melica asperifolia is a creeping grass of alkaline meadows and seeps around hot springs.
  8. Lawns can be formed by the stolon-producing Dichondra, a dicotyledon. Several other dicotyledons herbs found in the lawns of North America spread via stolons, including a weedy sorrel, Oxalis corniculatus and the nitrogen-fixing white clover, Trifolium repens.
  9. Other stoloniferous species that you may encounter include clump-forming species of Episcia (Family Gesneriaceae) in tropical forests or Shortia (Family Diapensiaceae) in cool temperate areas.

Stolon

From Wikipedia, the free encyclopedia Jump to: navigation, search Silverweed (Argentina anserina) picture showing red stolons. Enlarge Silverweed (Argentina anserina) picture showing red stolons. A stolon is an aerial shoot from a plant with the ability to produce adventitious roots and new offshoots of the same plant. The complex formed by a mother plant and all its offshoot connected by stolons are considered to form a single individual. A stolon is a plant propagation strategy akin to a rhizome.

Note that some species of crawling plants can also sprout adventitious roots, but these are not considered stoloniferous : a stolon is sprouted from an existing stem. Examples of plants that extend through stolons include some species from the genera Argentina, Cynodon, Fragaria, and Hieracium.

Vegetative reproduction

From Wikipedia, the free encyclopedia Jump to: navigation, search Production of new individuals along a leaf margin of the air plant, Kalanchoë pinnata. The small plant in front is about 1 cm tall. The concept of "individual" is obviously stretched by this process. Enlarge Production of new individuals along a leaf margin of the air plant, Kalanchoë pinnata. The small plant in front is about 1 cm tall. The concept of "individual" is obviously stretched by this process.

Vegetative reproduction is asexual reproduction, but other terms that apply are vegetative propagation and vegetative multiplication. In essence it is any process by which new plant "individuals" arise or are obtained without production of seeds or spores. It is both a natural process in many plant species (including organisms that may or may not be considered "plants", such as bacteria and fungi) and one utilized or encouraged by horticulturists to obtain quantities of economically valuable plants. Natural vegetative reproduction is mostly a process found in herbaceous and woody perennials, and typically involves structural modifications of the stem, although any horizontal, underground part of a plant (whether stem or a root) can contribute to vegetative reproduction of a plant. And, in a few species (such as Kalanchoë shown at right), leaves are involved in vegetative reproduction. Most plant species that survive and significantly expand by vegetative reproduction would be perennial almost by definition, since specialized organs of vegetative reproduction, like seeds of annuals, serve to survive seasonally harsh conditions. A plant that persists in a location through vegetative reproduction of individuals over a long period of time constitutes a clonal colony. In a sense, this process is not one of "reproduction" but one of survival and expansion of biomass of the individual. When an individual organism increases in size via cell multiplication and remains intact, the process is called "vegetative growth". However, in vegetative reproduction, the new plants that result are new individuals in almost every respect except genetic. And of considerable interest is how this process appears to reset the aging clock.

Natural vegetative structures

A rhizome is a modified stem serving as an organ of vegetative reproduction. Prostrate aerial stems, called runners or stolons are important vegetative reproduction organs in some species, such as the strawberry, numerous grasses, and some ferns. Adventitious buds develop into above ground stems and leaves, forming on roots near the ground surface and on damaged stems (as on the stumps of cut trees). Adventitious roots form on stems where the latter touch the soil surface.

A form of budding called suckering is the reproduction or regeneration of a plant by shoots that arise from an existing root system. Species that characteristically produce suckers include Elm (Ulmus), Dandelion (Taraxacum), and members of the Rose Family (Rosa).

Another type of vegetative reproduction is the production of bulbs. Plants like onion (Allium cepa), hyacinth (Hyacinth), narcissus (Narcissus) and tulips (Tulipa) reproduce by forming bulbs. Other plants like potatoes (Solanum tuberosum) and dahlia (Dahlia) reproduce by a similar method of producing tubers. Gladioluses and crocuses (Crocus) reproduce by forming a bulb-like structure called a corm.

Another type of asexual reproduction is apomixis. Apomixis is a type of reproduction involving unfertilized seeds to form new offspring. Hawkweeds (Hieracium), dandelions (Taxaxacum), and Kentucky blue grass (Poa pratensis) all use this form of asexual reproduction.

Horticultural aspects

Man-made methods of vegetative reproduction are usually enhancements of natural processes, but range from simple cloning such as rooting of cuttings to grafting and artificial propagation by laboratory tissue cloning. It is very commonly practised to propagate cultivars with individual desirable characteristics. Fruit tree propagation is frequently by budding or grafting desirable cultivars (clones), onto rootstocks that are also clones, propagated by layering.

In horticulture, a "cutting" is a branch that has been cut off from a mother plant below an internode and then rooted, often with the help of a rooting liquid or powder containing hormones. When a full root has formed and leaves begin to sprout anew, the clone is a self-sufficient plant, genetically identical to the mother plant. Examples are cutting from the stems of blackberries (Rubus occidentalis), cutting from leaves of African violets (Saintpaulia), and cutting the stems of verbenas (Verbena) to create new plants.

A related form of regeneration is that of grafting. This is a process of taking a bud and grafting onto a plants stem. Many nurseries now sell trees that can produce four or more varieties of apples (Malus spp.) from stems grafted to a common rootstock. PLUS, network!!!!

In nature the mother plant has all the dna (plans and information) and nutrients to initiate the new plant and help it take root and multiply itself. We don’t yet and so it is beneficial for us to see a network form that can provide some of that dna and nurishment. Production of new individuals along a leaf margin of the air plant, Kalanchoë pinnata. The small plant in front is about 1 cm tall. The concept of "individual" is obviously stretched by this process.

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