Rosette (botany)

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A rosette of leaves at the base of a dandelion Dandilion plant.jpg
A rosette of leaves at the base of a dandelion
Rosette growth form of the liverwort Ricciocarpos natans. RicciocarposNatans8.jpg
Rosette growth form of the liverwort Ricciocarpos natans .

In botany, a rosette is a circular arrangement of leaves or of structures resembling leaves.

Contents

In flowering plants, rosettes usually sit near the soil. Their structure is an example of a modified stem in which the internode gaps between the leaves do not expand, so that all the leaves remain clustered tightly together and at a similar height. Some insects induce the development of galls that are leafy rosettes. [1]

In bryophytes and algae, a rosette results from the repeated branching of the thallus as the plant grows, resulting in a circular outline.

Taxonomies

Many plant families have varieties with rosette morphology; they are particularly common in Asteraceae (such as dandelions), Brassicaceae (such as cabbage), and Bromeliaceae. The fern Blechnum fluviatile or New Zealand Water Fern (kiwikiwi) is a rosette plant.

Function in flowering plants

Often, rosettes form in perennial plants whose upper foliage dies back with the remaining vegetation protecting the plant. Another form occurs when internodes along a stem are shortened, bringing the leaves closer together, as in lettuce, dandelion and some succulents. [2] (When plants such as lettuce grow too quickly, the stem lengthens instead, a condition known as bolting.) In yet other forms, the rosette persists at the base of the plant (such as the dandelion), and there is a taproot.

Protection

Rosette of leaves of Agave americana Agave americana4.jpg
Rosette of leaves of Agave americana

Part of the protective function of a rosette like the dandelion is that it is hard to pull from the ground; the leaves come away easily while the taproot is left intact.

Another kind of protection is provided by the caulescent rosette, which is part of the growth form of the giant genus Espeletia in South America, which has a well-developed stem above the ground. [3] In tropical alpine environments, a wide variety of plants in different plant families and different parts of the world have evolved this growth form characterized by evergreen rosettes growing above marcescent leaves. Examples where this arrangement has been confirmed to improve survival, help water balance, or protect the plant from cold injury are Espeletia schultzii and Espeletia timotensis, both from the Andes. [4] [5]

Form

The rosette form is the structure, the relationship of the parts, and the variations within it, as shown in the following study from a herbarium:

As form, "rosette" is used to describe plants that perpetually grow as a rosette and the immature stage of plants such as some ferns.

See also

Related Research Articles

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<i>Hypochaeris radicata</i> Species of flowering plant in the family Asteraceae

Hypochaeris radicata – also known as catsear, flatweed, cat's-ear, hairy cat's ear, or false dandelion – is a perennial, low-lying edible herb often found in lawns. The plant is native to Europe, but has also been introduced to the Americas, Japan, Australia, and New Zealand, where it can be an invasive weed. It is listed as a noxious weed in the northwestern U.S. state of Washington.

<span class="mw-page-title-main">Scape (botany)</span> Long non-woody, leafless segment between two leaf-bearing regions of a plant

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<span class="mw-page-title-main">Marcescence</span> Retention of dead plant organs that normally are shed

Marcescence is the withering and persistence of plant organs that normally are shed, and is a term most commonly applied to plant leaves. The underlying physiological mechanism is that trees transfer water and sap from the roots to the leaves through their vascular cells, but in some trees as autumn begins, the veins carrying the sap slowly close until a layer of cells called the abscission layer completely closes off the vein allowing the tree to rid itself of the leaf. Leaf marcescence is most often seen on juvenile plants and may disappear as the tree matures. It also may not affect the entire tree; sometimes leaves persist only on scattered branches. Marcescence is most obvious in deciduous trees that retain leaves through the winter. Trees that exhibit marcescence are known as "everciduous". Several trees normally have marcescent leaves such as oak (Quercus), beech (Fagus) and hornbeam (Carpinus), or marcescent stipules as in some but not all species of willows (Salix). All oak trees may display foliage marcescence, even species that are known to fully drop leaves when the tree is mature. Marcescent leaves of pin oak complete development of their abscission layer in the spring. The base of the petiole remains alive over the winter. Many other trees may have marcescent leaves in seasons where an early freeze kills the leaves before the abscission layer develops or completes development. Diseases or pests can also kill leaves before they can develop an abscission layer.

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<i>Echinacea simulata</i> Species of flowering plant

Echinacea simulata, commonly called wavy leaf purple coneflower, glade coneflower, or prairie purple coneflower, is a species of perennial flowering plant in the family Asteraceae. It is native to the east-central states of the United States. Its natural habitat is dry, calcareous, open areas such as barrens and woodlands.

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<span class="mw-page-title-main">Plant stem</span> Structural axis of a vascular plant

A stem is one of two main structural axes of a vascular plant, the other being the root. It supports leaves, flowers and fruits, transports water and dissolved substances between the roots and the shoots in the xylem and phloem, photosynthesis takes place here, stores nutrients, and produces new living tissue. The stem can also be called halm or haulm or culms.

<i>Taraxacum</i> Genus of flowering plants in the daisy family Asteraceae

Taraxacum is a large genus of flowering plants in the family Asteraceae, which consists of species commonly known as dandelions. The scientific and hobby study of the genus is known as taraxacology. The genus is native to Eurasia and North America, but the two most commonplace species worldwide, T. officinale and T. erythrospermum, were introduced from Europe into North America, where they now propagate as wildflowers. Both species are edible in their entirety. The common name dandelion is also given to specific members of the genus.

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

Krigia is a genus of North American flowering plants in the family Asteraceae. Plants of the genus are known generally as dwarf dandelions or dwarfdandelions.

<i>Argyroxiphium grayanum</i> Species of plant

Argyroxiphium grayanum, commonly known as the greensword, is a species of flowering plant in the family Asteraceae, and a member of the silversword alliance, a group of over 50 species which are diverse in morphology and habitat but are genetically closely related.

<i>Espeletia schultzii</i> Species of flowering plant

Espeletia schultzii is a high altitude shrub endemic to the Andes of Venezuela.

Chrysopsis godfreyi, or Godfrey's goldenaster, is a North American species of flowering plant in the family Asteraceae. It is native to the states of Florida and Alabama in the southeastern United States.

<i>Cirsium altissimum</i> Species of plant

Cirsium altissimum is a North American species of plants in the tribe Cardueae within the family Asteraceae. Common names are tall thistle or roadside thistle. The species is native to the eastern and Central United States.

<i>Lactuca floridana</i> Species of lettuce

Lactuca floridana, commonly known as woodland lettuce, Florida lettuce, or false lettuce is a North American species of wild lettuce. It is native across much of central Canada and the eastern and central United States.

<i>Taraxacum arcticum</i> Species of flowering plant (arctic dandelion)

Taraxacum arcticum, the arctic dandelion, is a species of flowering plant belonging to the family Asteraceae. Its native range is Greenland, Northern Europe, Northern Asia and the Northern Russian Far East.

<i>Sonchus fruticosus</i> Species of plant

Sonchus fruticosus, the giant sow thistle, is a species of flowering plant in the tribe Cichorieae of the family Asteraceae. It is endemic to the islands of Madeira. The giant sow thistle is an impressive shrub native to the Madeiran evergreen forest habitat and growing up to 4 metres in height.

<i>Taraxacum ceratophorum</i> Species of flowering plant

Taraxacum ceratophorum, also known as the horned dandelion, is a species of flowering plant within the genus Taraxacum and family Asteraceae. This alpine species has a preference for mountainous habitat, where it can be found growing at elevations up to 3000 meters above sea level. It is native to a large portion of the Northern Hemisphere, inhabiting various countries within Asia, Europe and North America.

References

  1. Netta Dorchin; Jeffrey B. Joy; Lukas K. Hilke; Michael J. Wise; Warren G. Abrahamson (14 May 2015). "Taxonomy and phylogeny of the Asphondylia species (Diptera: Cecidomyiidae) of North American goldenrods: challenging morphology, complex host associations, and cryptic speciation". Zoological Journal of the Linnean Society . 174 (2): 265–304. doi:10.1111/ZOJ.12234. ISSN   1096-3642. Wikidata   Q99657406.
  2. 1 2 Botany online: Features of Flowering Plants – Leaves
  3. shows many images Archived 2008-07-05 at the Wayback Machine
  4. Goldstein, G. and Meinzer, F.1983. Influence of insulating dead leaves and low temperatures on water balance in an Andean giant rosette plant. Plant, Cell & Environment 6: 649-656.
  5. Smith, Alan P.1979. Function of dead leaves in Espeletia schultzii (Compositae), and Andean caulescent rosette species. Biotropica 11: 43-47.
  6. 1 2 Botany online: Features of flowering Plants – Rosettes – Whorls